Is there a resource that lists certifications for all available helmets?

I think the reality is that the best you can hope for is a per-country, per-tester, per-standard or per-certification list. There are many bicycle helmet safety standards I don't believe there is any single worldwide source of bicycle helmet certification info.

When you're at the store trying the helmet on to see if it fits comfortably, look inside the helmet for a certification sticker.  Mine has a Snell sticker that says "B90A" and I can go to Snell's Helmet Certification List to search via the testing standard (B90A), make and model to find that they have tested that helmet to that standard.  (and if I want I can also look around for the details of that standard).

Or perhaps you're not trying the helmet on and are contemplating buying the helmet site unseen? That sounds likes a bad idea to me, I'd want to insist on trying on a helmet before buying to make sure it fits my particular head well.

Snell essentially has their own higher standards that exceed the standard US standards and has a very nicely searchable online database.  POC does not appear to use Snell because they don't list Snell on the POC for the other helmets and I can't find POC helmets on the Snell site.

The POC link you provided has some stuff with a European standard (EN), some with a "CPSC" and some with "ASTM".  CPSC is the US "Consumer Products Safety Commission" who certifies testing procedures and testing labs and publish recall information, but I don't believe they actually do helmet testing directly. ASTM seems to be a worldwide standards organization, who similarly to CPSC certifies testing procedures, not helmets.

It's quite likely that POC uses the same outside lab for testing all of their helmets to the standards, so it's worth looking at who certifies to those standards they do list.

By searching on ASTM's website for "bicycle helmet" and clicking the "Laboratory" refinement button, and they have a listing for Biokinetics and Associates and ICS Labs. Otherwise ASTM's site isn't really very useful...

Biokinetics has a client listing that includes Bell (one of the bigger helmet manufacturers), but not POC.  No product listing.

ICS doesn't appear to list their clients, and the Certified Products link is under construction.

Which all leads back to: look inside the helmet for the certification sticker.


Bicycle clicking popping sound felt in the pedals usually when pedalling hard

That sounds like something wrong with the chain. You may just have a worn chain that is skipping over the rear sprocket. I'd do a check of the whole drive train to rule all potential issues out.

Check for play or roughness in the pedal bearings
Check for play or roughness in the bottom bracket bearings
Check chainring bolts are tight, chainrings don't have any play
Check cassette / freewheel / rear sprocket for any play
Check sprocket and ring teeth for damage or wear
Check rear wheel axle for play or roughness.
Check chain for stiff links
Check chain for wear and elongation with a chain wear gauge


Swapping cranks, but the new crank is wider, how do I compensate for this?

You're right, you want to space it between the shell and cup.  You can put spacers on either side to get the chainline right.  Most cranksets come with spacers (2.5 mm is probably the most useful size for you) but if yours didn't any LBS should have a few to sell you.  Something like this: http://wheelsmfg.com/bottom-bracket-spacer.html (I don't know if these work with hollowtech BB's or not)

You'll probably want to get an assortment of sizes if you can, and use as few as possible to get things lined up (I assume this would help maximize BB stiffness, but really I just hate having excessive spacers - makes it more likely I'll lose one when disassembling/reassembling).


The star cutouts in the lugs and BB identify it as a Guerciotti. I couldn't find vintage Guerciotti star pictures on their site, but there are other photos easily available via a Google image search.


How do I get my brakes to stop squealing

There are a few causes for brake 'squealing':

New pads. After a bit of wear (or sandpapering), the squealing will stop.
Misalignment. As some others have mentioned, misalignment may cause squealing (although it would be reduced with some wear). Check out Sheldon Brown's tips for alignment suggestions.
Oil or water on the rim. Either of these substances, even in small portions, combined with dirt or debris on the rim can create squealing. Wipe the rims thoroughly on the braking surface, as  well as the pads, with a dry cloth.
Incompatible rims/pads. No one else has mentioned this, but this is often the most common cause. Rims are generally made from one of two materials: steel or alloy. (You can tell the difference by seeing if a magnet will attract (steel) or not (alloy)). Incidentally, brake pads are made of specific compounds to work on one or the other. Often, using pads designed for alloy rims (like most Kool-Stops) will squeal if used on steel (which I'm guessing you have).


Well, the thing to do first is to determine if the crank arm is bent (or loose/poorly fitted to the shaft).

Prop the bike up and "pedal" it backwards with your hand (from the right side).  Observe whether the shaft of the pedal maintains the same horizontal alignment all the way around.  If the crank arm is bent then generally the pedal shaft will be "pointing upward" at the top of the crank cycle and "pointing down" at the bottom of the crank cycle, and you can usually both see this and sense it with your hand.

(Note that a bent pedal shaft can produce the same symptom, though.  But if the pedal shaft is bent it will be obvious if you unscrew the pedal -- the shaft will "wag" around as you unscrew it.  And either way you'll need to replace some components.)

It should be noted that, on bikes with 3 front sprockets, the right pedal sticks out from the frame slightly more than the left pedal, making your ankle slightly more apt to bump the right crank arm than the left.  But the difference is slight -- maybe 4mm.


You were probably doing intervals, or at least your effort was at a high effort for several minutes, followed by a recovery for several minutes, and another high effort rather than an extended "steady" output to exhaustion.

In general, you're right, the maximum mean power for a duration should be a monotonically decreasing function of duration. However, for any single ride, especially when you're doing intervals, the MMP for that ride needn't be monotonic.

Here's a simple (too simple) numerical example. Suppose you were doing repeated 5 minute intervals, with 5 minutes at 325 watts followed by a 5 minute recovery at half that, or 162 watts. If you were to calculate the MMP for a duration of 9:00, it would be 252 watts; the MMP for 13 minutes would be higher than that, at 262 watts. You didn't do an extended effort for either 9 or 13 minutes but that doesn't prevent the arithmetic of calculating an average power over 9 or 13 minutes. In your case, it appears that your workout was on an ergometer and involved at least one 1 minute interval at 450 watts. Depending on how long your work and recovery intervals were, and at what levels, you can see non-monotonic MMP curves.


How bad is a bent rim, how to deal with it and how urgent and dangerous is it?

Riding a slightly bent rim is typically not dangerous. I've continued to ride bent rims on my bikes for many months. Eventually, it may get worse, especially if you are learning 180's or how to jump. The bend is a weak spot that can get worse if you land on it with the same side loads again. From your description, it sounds like it isn't a giant bend— you can only feel it vibrating at high speed, and it isn't bent enough to contact your frame or otherwise disrupt how your wheel rolls.

It could be dangerous if the rim is cracked at all. Usually a rim only cracks under extreme damage, or after months of riding it bent, and at that point becomes much weaker. A cracked rim could collapse under load, or especially harsh impacts like landing jumps. Inspect your rim again for cracks around the bend just to be sure.

Usually, a bike shop can fix your wheel. Most bicycle wheels consist of the rim, spokes, and a hub at the center, with a bearing and axle that connect to your frame. The spokes actually give your wheel most of its stability. It's similar to a suspension bridge, where the rim is not super strong by itself, but with tension from the spokes it becomes much stronger.

If your wheel is this type, a bike shop can "true" your wheel by tightening and loosening the spokes around the bend. They have special tools to help get your wheel back in true (straight) by making minor adjustments on the spokes throughout your wheel. Usually truing your wheel doesn't require new parts, it just requires labor, and should be under $50. Also, a good wheel true can make your wheel stronger, so you might have less problems with it in the future.

This does depend on the type of bike and wheel you have though. Cheaper rims can be harder to fix, and if its bent too badly to be trued, you may need a new wheel.

When dealing with the bike shop, simply show them your wheel and ask if it can be trued. If yes, they'll tell you a price and when they can do it. If not, you can ask them about new wheel options. Replacing just a rim with your old hub and spokes is very labor intensive, which is expensive. It sounds like your wheel should be truable. But if it is not, the shop will want to sell you a new wheel, because it simply isn't practical usually to replace just the rim.


SRAM GXP crank installation and rear hub preload

By amazing co-incidence there happens to be a video on YouTube showing SRAM GXP crank removal and installation on a Bike Trek Superfly 6.

            .

Referring to that video, on the non-drive side it's (from inboard to outboard): red rubber seal, black plastic spacer, metal wavy washer. On the drive side there is only the red rubber seal.

Looks like your bike shop has omitted the black spacer on the drive side.


How do I remove a pedal from a crank with a crossed thread?

I'm guessing the pedal is toast too, but if I wanted to try to save it (and it refused to come out with simply a wrench and a hammer -- counter-clockwise on the right, clockwise on the left) I'd get out my trusty Dremel and make a slot or two in the crank, parallel to the pedal shaft.  (It won't hurt if you nick the pedal threads a little bit.)  Then drive a small cold chisel into the slots to spread them a bit.

(I do wonder how you managed to cross-thread the pedal and then ride on it.)


Looking for a new bike, any tips for buying a good bike?

You don't say where you are located, so it is bit hard to tell what your specific requirements might be, but you do make a distinction around 'winter riding'.  So let's assume you mean cold, perhaps treated roads, perhaps snow, perhaps ice.

For tires, while there's some tension between 'wide' and 'fast', I would suggest 32mm or wider, if they'll fit in your frame, fork, and brakes.  Something with tread if you plan on riding in the wet or on treated (gravel-covered) roads.  If you expect to encounter ice, you may want studs.

Another unknown is time of day and what the lighting conditions will be.  In my opinion the single biggest safety improvement you can make is to ensure you are visible in darkness and in low light, to drivers who are in a hurry, tired, and often distracted.

I would recommend highly visible (hi-viz yellow and orange) clothing, many reflectors (especially moving reflectors, such as ankle bands and spoke reflectors), a bright, multi-mode, rechargeable stroboscopic rear light; a bright, constant-beam, rechargeable front light, and an auxiliary stroboscopic white front light.  There are many good choices out there.

There are also helmets with integrated safety lights available; these work well in my experience.

If you are looking for specific product recommendations I'm sure many folks can provide them.


If the B-screw is too loose, would it significantly increase wear?

Sounds to me like your Rear Derailleur simply can't cope with a 34 tooth rear cog.  You could replace the cassette with a 32 or 30 tooth maximum, perhaps find a smaller upper jockey wheel, or simply don't use the 34 tooth gear without drastic need.

My folder has similar problems with on its largest cog because the top jockey wheel is interfering with the cassette.  The teeth in the jockey wheel (pulley) directly touch the cassette's teeth.  I simply put up with it, because both are wear items and will be replaced in due course.


Need a method to wrap H-bars with handlebar tape

I'd wrap in two passes: first, from the bottom stubs to the join, just crossing over onto the ends of the main bar. Then tape this up tight, to squash it down. Secondly, I'd wrap from the tops of the bar ends around the joins and all the way up to the stem. The second pass should cover up the tape holding the first bit of wrap.

Maybe something like this (excuse terrible paint skills)?


Is it a good idea to get a narrower front tire and a wider rear tire on a road bike?

I'm currently running the Conti Attack/Force combo on my road bike. I have previously run both the GP 4000, and the Schwalbe Ultremo ZX on the same bike.

The concept behind the Attack/Force is that the slightly wider (24mm) rear tire will allow just a bit more comfort, and the slightly narrower front tire (22mm) will be a touch lighter with more reactive handling.

I feel a difference in comfort, but I can't say the handling was noticeably different. Of course, the GP 4000 was pretty stable to begin with, so maybe that's a good thing that I don't notice a change.

They do feel a bit more stable in a corner, and I feel like the rubber compound is a bit stickier. They say it's the same Black Chili compound used on the current GP 4000, so maybe that's psychological.

I can say that the comfort aspect is worthwhile, and there is nothing I have bad to say, so why not try them. A set (here, at least) is the same price as a set of GP 4000's. No loss, at least, and a bit of gain on the comfort side.

@DanielRHicks commented that you might need to worry about braking power or traction. I've had no issues with braking performance, and these are a pro peleton tire. I don't see any issue there. I've also had no issues with flats on the tires, but then, I didn't have with the GP 4000 either.


I've verified that the hub spacing is 145mm - standard for a tandem.  The hub on the bike is unmarked, unbranded, and Trek's website simply lists it as "alloy hub".  It appears to be a 135mm hub with a longer axle and spacers in place.


Bottom bracket harder to turn half way around

When I turn my cranks with no chain attached, it's pretty smooth, no real noise and just goes for a while if I let it spin.

This does not look like a bad bottom bracket.

When I attach the chain I can turn about half a rotation freely and then it becomes stiff and seems to be in the same place each turn.

However, chain and other attached stuff creates a side load onto the bottom bracket, which may skew the crank axle a bit, and that may reveal looseness in BB's bearings.
Have you tried to wiggle the cranks side to side by hand when they are installed? If you can see or feel noticeable play, then it is a sign of worn bottom bracket.


Two extra teeth will increase your gear ratios by 6% (34/32 = 1.06). What it will not do is help retain you chain any better.

Did you shorten the chain when you removed the inner and outer rings? (Assuming that's what you did.) If you didn't that may be why you are dropping the chain - it's too slack. BTW, you can re-install the front derailleur to act as a chain guide.

If you did shorten the chain you may have to replace it to accommodate the new larger chainring.


It sounds as though you are talking about what Sheldon Brown term "reach", which is

  normally measured center-to-center along the direction of the extension

So this does not take into account the angle of the stem, which could reduce the length forward that the handlebars extend by a small amount if they are on a large angle up or down.


How to prevent Brooks Cambium C17 saddle from wearing through pants

It's difficult to know as you haven't said what your are wearing exactly. I have this exact saddle and have covered approx 8,000km on it- wearing out no clothing (that I have noticed). I'd suggest that you saddle position is possibly not quite correct and you are moving slightly through the pedal stroke- causing friction and wearing through the clothes you are wearing. I'd look at possibly moving your saddle up, as having it too low tends to cause the hips to move outwards/in on each stroke. Alternatively, you are wearing clothing that is not designed with cycling in mind & should perhaps look at buying some.


Carbon fiber fork scratched. Paint over or replace?

Personally, I'd put some clear (UV stable) epoxy over it and not worry any more about it.

My MTB has a carbon rear triangle and I had a landing go sideways (literally) when the knobs on the rear tire kicked hard left and started grinding through the clear coat and down through the CF. I stopped the bike as quickly as I could, re-aligned the rear wheel and kept riding. I didn't have time to have it repaired before MTB National Championships last year so I raced it just like that and still finished 9th. I then got some quotes and had it repaired by Calfee earlier this year. It looks and feels even stronger than it did prior to the repair.


What you have is a 'one-piece' or 'Ashtabula" crank. Info can be found on this Sheldon Brown Page. They are called one-piece because the crank arms and axle are made from a single bar of steel.

The chainrings are not fixed to the crank axle and can rotate on it, instead there is a 'drive pin' that sticks out of the right hand crank into the chainring spider. That's what has broken off your crank. From the picture, I think it was press fitted into the crank and worked loose.

I did some quick googling and found that replacement arms are available and inexpensive. Your chainrings do not look worn so you will be able to reuse them (although they could use a good cleaning 😉).

If you are not experienced with bike repairs a local bike repair shop will be able to handle replacing the crank easily.

Update:

Park Tool has a good video on disassembly and servicing the bearings and re-assembly.


Is it safe to run disc brakes up front on a mountain bike that lacks a disc caliper mounting point in the rear?

A few years ago this was a reasonably common setup as sold. I've certainly ridden an e-bike set up that way, with v-brakes at the back and a mechanical disc brake at the front. I suspect this wasn't so much about stopping power as not needing maintenance between services, though in practice some adjustment was required even if less than at the back.


How does Google Maps estimate cycling times

This site seems to have some good answers to your questions. It says

  Google assumes a baseline moving speed of around 16km/hr (10miles/hr) regardless of trip distance.

but if you read more you can see there are adjustments to that baseline. For some routes where I've actually compared, I divide the Google cycling time by 1.5 to get an estimate of how long it would take me, but I used to race pretty seriously.


Can BSA 68/73 bottom bracket be used in place of fat bike BSA 100 mm

The spacing is the only difference across the SRAM/TRUVATIV GXP line of BB's, so yes, you can use the 68/73mm left/right cup set on your frame. Just reuse the center seal/spacer from your existing BB, especially if you're riding a lot in the winter or rain.

Funny enough I've seen cheaper prices for the less widely used 100mm than the far more common 68/73 so it might make sense to just buy the right width unless you've got a good BB source!


Which way should a seat post clamp be oriented?

Typically, for an aluminum post you align the gaps. For a carbon post you turn the clamp 180 degrees from the gap in the seattube to minimize the chance of crimping the seatpost. Some manufacturers have their own recommendations, but they're typically in line with what the aforementioned guidelines.


Should I rotate the tires on a (grown-up) trike?

Swapping the tires around (or if they have some sort of quick release axles, the wheels) isn’t going to do any harm, and will prolong the useful life of the tire if they are contacting the ground at an angle.

How often to do it is hard to tell. Depends on how many miles you ride / week, mass of you plus bike, roads surfaces etc. I’d probable swap tire around when I begin to see some wear.


700ccx28 rims with 25 tread and 28/32 tube does it work?

I think you need to find a new shop.

Your typical Velox rim strip should last on the order of decades unless a spoke goes through them or something (and that should be fixed, not just putting a new rim strip), so I'm not sure why it was replaced (or if it was done properly -- right size tape, covering all the spoke holes, aligned with the valve hole which is clean).

The tube size shouldn't be a problem. My suspicion is that you're not running high enough pressure, or aren't installing the tube properly (having the valve free and straight). I'm not sure why the shop owner didn't put a 25c tube in though, considering they're probably the most common size to have on hand.

As for tire wear, using brakes rather than skid stopping reduces tire wear. But, increased tire wear does come with the fixie territory, I suppose. Skidding wears the tire unequally depending on the chainring and cog size.


Had the front derailleur adjusted, now it feels like the rear is skipping

It's hard to tell, but what you are describing does not have to mean that anything is broken. The most likely cause would be improper adjustment of the rear derailleur. It may seem outrageous after two tune ups from two different shops, but you have little to lose in at least trying. Oh, and you will not need your box of tools for this, sorry!

Watch this video. Pay attention to the last part, the barrel tension adjustment, which I think may be what's bugging you. Although the website you linked says your bike is equipped with SRAM, Shimano has a detailed procedure to adjust that tension, which you may want to follow: as far as I know all brands work more or less the same. The document I have linked is for a random rear derailleur, but the SIS adjutment part, which is the only one you should worry about, is the same for all.

If you can't get it to work, then I would recommend getting it to a bike shop. I would think that any of the two you have already been to should at least take a look at it without charging you anything.


Freehub disengages and then rengages — what is the issue?

Most likely pawls or other parts of freehub's engagement mechanism have become sticky. Opening it, cleaning it up and applying light grease (if at all) should help.

Much less likely but not impossible is that the pawls have become worn. Replacing them is then in order. In any case, servicing the freehub is the first thing to do.


"Proper" cycling posture on a road bike with drop bars?

Whatever works.  The main advantage of the standard drop bar is that it offers you multiple hand positions and multiple postures.  In a sprint, or driving into a headwind, riding fully on the drops cuts wind resistance, but for less intense riding one of the several hand position on the top bar or on the hoods is usually preferred.  And on long rides the ability to change positions from time to time is invaluable in terms of hand/arm/back comfort.

And there is no one "right" height for your bar.  If you're a real aggressive rider (and young and limber) then a lower bar position may be for you, but if you're somewhat more casual there's nothing wrong with raising the bar (so to speak).  And you may also want to consider adjusting your "reach" by changing the stem -- not everyone's torso is the same length.


SPD vs. SPD-SL: Which unclips most easily?

In my experience, Time/Mavic Iclic.

This should, however, not be the reason for decision. Both are easy enough to unclip if you remember to twist your foot instead of just lifting it and neither will unclip if you forget it. Don't believe the people who claim falling is part of learning, just practice leaning against a wall and unclip a couple of hundreds times or until it feels natural.

What you should consider is:

SPD-R and road systems in general are very uncomfortable to walk in. They are compatible with some very nice and lightweight road shoes, work very well with shoe covers and have some roadie credibility
SPD is walkable (but uncomfortable, has loud crunching sound on pavement/rocks and destroys floors), compatible with MTB shoes including waterproof and insulated ones and has credibility among grumpy stackoverflowers. There are some SPD shoes that look like road shoes but are in general heavier and less stiff.


Touring as a noob... Daily duration and distance?

When I was 15 a friend and I somehow convinced our parents to allow us to go touring for a week; we were Boy Scouts and I'd read a book on touring.  We mounted racks and panniers on our cheap bikes, strapped a relatively-heavy tent down, and headed off.  We hadn't trained particularly, other than being typical kids of the pre-internet era who pedaled all over town all day in the summer.  We probably averaged about 40 miles per day on our tour, and we had many memorable adventures that make me smile to think about them even now ;)

Being middle-aged now, with a sedentary job, if I were to attempt a similar trip I'd have a much nicer touring bike and lighter gear, and I'd want to train for several months beforehand.  It's one thing to be able to ride a bike loaded with 20 lbs of gear for many miles in a day, and it's another to be able to do that for several days in a row with only mild aches and pains.  But you're not me; if you're younger and stronger, you might have no trouble just jumping on the bike and going.  Also there's no rule about how far you must go in a day; personally I'd plan for about 50 miles per day on average (more on some days and zero on others), but if you and your friends want to just pedal lazily for two hours and then camp by the nearest swimming hole, then go ahead and do that.

One thing that I can say definitively is that in order for touring to be fun, you have to want to do it.  The idea of pedaling a bike for a week straight should sound wonderful; it should excite you and fire your imagination.

The subject isn't often discussed here, but we hard-core bicyclists are a funny bunch.  Just pedaling a bicycle, feeling the breeze in the face and leaning through curves, is fun for almost everyone able to do it.  But pedaling hard or pedaling for a long time is painful.  We hard-core bicyclists get a sort of runner's high, often attributed to endorphins, which is its own reward, and makes the pain worthwhile.  Not everyone gets the same reward in the same proportion.  That feeling, the many healthy benefits of the exercise, and the simple joy of riding (plus the desire for the respect of our riding peers, for those of us who ride in groups) is what motivates us to keep riding.

If you're considering whether touring is right for you, you might try training for a month.  Ride at least two or three days a week.  Work up to riding at least two hours in a session; you might have to start easy, as little as fifteen or thirty minutes, to get your body used to it.  (Padded bicycling shorts help a lot; don't wear anything under them, or you'll have trouble with chafing.)  Push yourself, not so hard that you can barely talk, but enough that you feel like you've accomplished something afterwards.  At the end of the month, if you feel like the training was worth it and you want to continue, then you'd probably enjoy touring.


How much float do the Speedplay Zero pedals have?

I read the following, from their website as having the option to either lock them in place and use them as a fixed cleat, or use them with up to 15º of adjustable float, which considering many are only about 7º seems like a lot.

  By thinking "outside the box", we created and patented the most
  technically advanced pedal system ever, featuring your choice of
  either a fixed position or up to 15 degrees of micro-adjustable float

I personally have no experience with them though, Nor have i heard much about them, that is just how i interpreted it.


Is the durability of more expensive chains better than cheaper ones?

No. The only advantage of expensive chains within a specific brand is the minor reduction in weight. The ones with extra plating do look nicer and provide some corrosion resistance, but it takes almost no effort to keep your chain rust free.

There are differences between various manufacturers, but in general those relate to shifting and how the quicklinks work, not the chain life. (i.e. if you like how SRAM chains work on your bike, buy the cheapest SRAM chain. )

300/400 miles is a very short life span for a chain. Two things might help you extend the life of your chain.

If your rear cluster is worn, that will quickly wear out a chain.
On the other hand if you replace your chains regularly a rear cluster can last a very long time. If you have lot's of miles on the rear cluster consider a replacement. Any time you replace the rear cluster you should replace the chain. Front chainrings can also cause wear, but they take a lot longer to wear out.
Excess lube on the chain. In a dusty dirt environment any lube on the outside of the chain creates a grinding paste that will wear a chain quickly. Chains actually move very little. All they really need is enough
lubrication to prevent corrosion inside the rollers. If you're riding in
dirt and dust wipe the outside of the chain as clean as possible before installing it.

Point 2 is controversial, all I can say is I ride on fine clay soils that destroy chains and it has worked for me to greatly extend the life of both chains and expensive gear clusters.


Mountain Bike Disc brake pads price vs performance

TL:DR bullet point version at the end.

Since you do not specify the pads at those price levels, I chose to interpret the question as what are the potential differences between brake pads.

You said you know the difference between resin and sintered (there also exist semi metallic pads as a kind of middle ground), well resin and sintered is a huge difference (see end of answer for more info), you will not experience a difference anywhere near that magnitude between pads within each compound.

The next "biggest" difference is heat dissipation (which is actually also a difference between sintered and resin) I'm sure there are some other options out there, but I'll stick to the one I know:

Shimano Ice-Tec finned pads give better heat dissipation, this reduces fade and improves pad life (both in theory and in my own experience).

Lastly there are some minor differences like titanium backplates or slightly different compounds, never been able to tell the difference between different resin compounds or different sintered compounds, except once when I had a pad emergency and got some horrendously fast wearing and crap braking resin pads from an LBS, can't remember what they were, but they were the most expensive pads I had had at the time (pre ice-tec days).

The above are the real differences, beyond that, it's just brand, marketing and profit margins (not that I could tell the difference between normal and Ti backplate sintered shimanos, so backplates are crap unless proven to reduce temperatures... although the backplate would make a difference if you wore through the pad and used the backplate...)

Oh there are also people like Mr.Magura on mtbr forums who have made carbon discs and pads, while his creation is impressive, there have been some attempts at commercial versions but all have been total crap as far as I am aware, but it's worth mentioning that pads for those discs no doubt have a lot of differences to standard pads.

Resin vs. Sintered,

Sintered have:

More bite (and less modulation).
More stopping power.
The ability to stop you effectively in the wet.
Less fade.
Slower wear on the pad (but faster wear on the discs)
Compatibility issues with some (usually cheap) disks.
A Reputation for being loud (but I don't find this to be the case, IME there's very little difference, unless you haven't bedded in properly, or haven't set everything up correctly.)

Resin has:

Better Modulation (less bite)
Allegedly make less noise.

TL;DR Version:

Heat dissipation via fins = less fade. (important to some people, but
not most)
Minor compound differences, back plate material. (irrelevant to most
people)
Marketing bullshit and profit margins. (irrelevant to most people)
Resin pads (+modulation +quiet? +wear on pad)
Sintered pads (+power +wet performance +wear on disc +less fade)
Semi metal pads (between the other two)


Can jockey wheels be used in either position in derailleur cage?

The top and bottom wheels are different. The top wheel's bearing allows some lateral movement. They come as a set and are not expensive so just replace both together.


The first human-powered, fixed-wing aircraft flew in 1961, the SUMPAC. Several other such craft were flown in the 60's and 70's, including the Gossamer Condor, which won the prestigious Kremer Prize for human-powered flight. All of these were powered by a human pedaling, like on a bicycle.

An aircraft with wings that flap like a bird's is called an Ornithopter. None that I can find were capable of getting into the air on their own. Early, unmanned ornithopters were powered by large rubber bands or gunpowder charges. The first verified human-powered ornithopter flew in 1929, but it too was towed into the air.


Mapping the most gentle route for my single speed

That's 4 days to evaluate all the routes. I'd just ride them. You can spend a lot of time with mapping tools trying to evaluate gradients and still get it wrong. Unless you can find a cycling guide that discusses the issue you will almost certainly not get a good answer. For a motor transport engineer (the people who design roads) anything under 1:10 is fine on a minor road, 1:20 on a major road. They just don't care about short steep sections vs long gentle sections. The flattest route could easily be the one where you come out of a compulsory stop onto a short steep section that climbs less than the 5m interval between contours on a most-detailed map.

One electronic solution would be to use google streetview to survey each route. Look at the angle between the street and the vertical walls or horizontal floors. That will give you a rough idea of the slope of the road at each point.


What is the cause of my fork wobbling when applying the front brake?

There are a number of things that could contribute to such a feeling.

You don't mention the type of brakes you have, but disc brakes can contribute to such a feeling since there is some flex between the breaking point (the disc/caliper) and the contact point (the patch of tire touching the ground).  If you have a "flexy" wheelset, this may be something to get used to.  If the brakes are not adjusted properly or are loose, it's possible your disc caliper is moving as well.

Your headset could also be loose, meaning the steertube is moving around inside the frame and should not be.  A headset adjustment may fix this problem, if none of the components are damaged.

Finally, if you have a suspension fork, it's possible you are misinterpreting some suspension compression as an issue (it isn't).  However, it's also possible (with a suspension fork) that the upper and lower are poor fitting and you are experiencing movement that you shouldn't.

Without more information and specifics, your question won't have a firm answer.


This is only engineering judgement, not technical analysis: the damage does not appear particularly serious or significant at that location. As Daniel advises above, keep an eye on it for cracks developing. If you are just a "normal" everyday type user it could be OK for quite a while. The Al frame will eventually crack and fail, not necessarily at this location. If you are a strong hard core competitor, then you wouldn't even consider using it for highly demanding duties would you?


Should I change the tire and tube or can it be patched?

What can you afford?  If you're not really struggling financially you should replace the tire.

If you cannot afford that (or if you need a temporary fix while you're obtaining a new tire) then you need a "boot" inside the tire.  A "boot" is some piece of flat material (typically about 5 cm x 5 cm, though size can vary based on tire size) that is flexible but still stiff enough to resist the pressure of the tube trying to poke through the tire.  You can buy purpose-made boots made from plastic or rubber, you can cut your own boots out the (thin) sidewall of an old road tire, or, popular in the US, you can fold a dollar bill up several times and use that.

The boot is used by inserting it into the tire after the tire is mounted and the tube is in place.  Pry the tire off the rim near the hole and slide the boot in between the tube and the hole.

Using a boot is not as reliable as replacing the tire, of course.  There is a danger that the boot may shift over time, especially if the tire pressure is not properly maintained.  And a boot is an even less reliable fix for a hole in the sidewall of a tire.

The tube is actually less of a worry than the tire.  If the hole is a puncture rather than a cut/slit, or it's a very short slit, then you can patch it with conventional tire patches.  If the cut is so large that a standard bike patch will not comfortably cover it (with maybe a 10mm margin) then the tube needs to be replaced.


Your steering geometry has obviously been messed up by the installation of the new fork.

I'm guessing the new fork is longer than the old fork.

An old RockShox suspension fork would have very little (by modern standards) travel, and the distance from axle to bottom of the head tube would not be much greater than a rigid fork. Modern forks have longer travel, are designed for bikes with higher head tubes and are significantly longer. if you put a longer fork on a frame it pushes the head tube up, increases the head angle and positions the front wheel too far forward.


Carbon steerer with expander plug under the stem, should I be worried?

Should you be worried, I wouldn't be. The alloy expander will stop the carbon steerer from being crushed. Remember the max torque on the stem bolts will likely be less than 6nm. (Use appropriate retaining paste and don't over tighten it!)

As you mentioned, a lot of people (me included) will recommend a 5mm spacer on top of the stem, with the steerer a bit longer, to be extra safe.

But plenty of people refuse to have spacers above the stem for various reasons, mainly aesthetics, and they are fine, assuming the expander insider the steerer is of good quality.


Are more expensive chains/casettes more quiet?

I think a well-adjusted, modern system from any of the major players in components will be reasonably quiet and generally the same volume level. The trick is to make sure your cable tension, limit screws, and derailleur alignment are tip top. But that's true even if noise isn't an issue.

In your case, I would guess that your trainer will be much louder than your drivetrain.


The fundamental problem with synthetic garments is that some of the fibres (particularly early nylon and current polyester) have spaces within the fibres that are perfect-sized cocoons for growing the bacteria that give rise to body odour. 'Boil wash' the garment to kill the bacteria and you damage the fabric. Cold-wash to look after the fabric and you don't kill the bacteria. It means you cannot win on a regular machine wash.

As mentioned vinegar (an acid) works to kill the bacteria. The same goes with a domestic alkali such as baking soda. If this pre-wash is too much effort and you just want the bacteria killed then you can get TAED or 'oxy' add-in for your wash - same aisle as the regular washing powders, smaller packs. This works at low temperatures and with my clothes but there is no way in a million years that I would advise an 'Assos' garment (or equivalent) be washed with TAED.

You can also invest in the base-layers that have silver particles embedded in them. These are up-market garments that cost a bit more but pay off in the no-smells department.

Also of use is a dehumidifier, the DeLonghi DNC65 will work wonders in the changing room at work or at home in the winter months to purge moisture from the air where your clothing develops its pong. A lot of life's problems were solved with the DNC65 for me and my invariably damp cycle attire.

The aim of the game is to not have the bacteria grow, it is therefore best to shower before riding to work (not at work) as fresh sweat does not smell - just the bacteria that develop 12 hours later (when you are home). Therefore, clean body and no bacteria gets transferred to the clothing - it stays that bit cleaner.

I don't think anything can be done with cheaper fabrics that get infested with bacteria - a good set of quality items, washed as per the instructions and kept scrupulously dry in-between rides with a bit of 'oxy' added to the wash is the best strategy. You also want to avoid merely disguising smells - the deodorant strategy - as that does not really work.


What are these holes for in my Diamondback Sorrento?

They are rack and fender mounts and you cannot install disc brakes with them.

I.S. mounts are 51 mm apart, and post mounts are 74 mm apart (and look totally different). For more details on these mounts, see this answer.


Can a XTR 2016 di2 bracket axle unit fit in XT 2016 rear derailleur?

Here is the Shimano Exploded View PDF for the Di2 mech (pdf download):

And for your XT one (pdf download):

What you can see from those documents is that the Bracket Axle Unit aka B-Axle is very different between XT and XTR Di2.

I would expect them not to be compatible.


Aerobar, why would carbon cost more than aluminum?

You may have been missing the different armrest offset ranges. I have relatively little experience with clip on aero bars, but I think offset, which is Profile’s term, relates to fore-aft adjustment. If I’m interpreting correctly, the carbon bars’ armrests can be positioned further aft. Perhaps this is a desirable characteristic that people might be willing to pay a premium for, but perhaps it is not (see Chris H's comment on this answer).
I suspect there’s nothing intrinsic about material properties that enables the carbon bars to withstand that more rearward position where the aluminum ones would fail. I lack experience with this type of product, so I could be wrong. But basically, this specification difference could just be pure marketing.
In general, carbon does dampen vibrations better than aluminum, and cyclists are willing to pay premiums for carbon handlebars. However, I am not sure how this plays in with clip on aero bars, which are clamped to your existing handlebars.
Last, as a side note, manufacturers’ specified weights can be off. Usually the mean actual weights are higher than what they specify. Also, there will always be some variance around the weight, I.e. each aerobar will vary randomly in weight. That variance can also be systematic. For example, aluminum rims are extruded through dies. Because of entropy, the dies wear slightly through their life, so the mean weight of the rims will creep up over time.
Your title implies a question about which to get. You could attempt to confirm this with a shop that deals with a lot of triathletes. They’ll be more familiar with this product as well as the specific brand than I am. If there’s a shop that has a lot of long distance riders, including randonneurs or bikepackers, they might also be familiar with clip on aero bars as many members of those community use clip on aero bars. At any rate, if the specs on Profile's website are factually correct, it is not clear if there are functional advantages to the carbon bars.


Apart from special cases (IIRC one-piece cranks, really old french bicycles), the standard you mentioned is the universal pedal thread standard. So unless you specifically rent a bike with obsolete pedal standards, no technical reason will prevent you from using American pedals.
(You should obviously make sure that the owner of the bike is fine with changing the pedals!)


What are the main differences in Giant's Toughroad and Revolt drop-bar bike series?

I think you are confused about the frame 'technologies' that Giant offers. More boxes checked does not mean a better frame, the choices are mutually exclusive. 'Advanced Composite' means a carbon fiber composite (CFC) frame. 'ALUXX' means an aluminium alloy frame. CFC frames are generally held to be superior to alloy ones.

I'll give you that the 'SL' and SLR postfixes are confusing, intuitively they would appears to indicate a progressively higher grade of either CFC or alloy construction, but the lowest spec bike has the SLR tag.

It's very obvious that the Revolt Advanced is the better bike, and the Toughroad the inferior. Generally the Toughroad series sits below the Revolt in Giant's range, with a bit of overlap.

The 'gravel', and 'adventure' adjectives don't mean much. Asking who are these bikes are for is a kind of meaningless question. What you should do is find stores that have the bikes you are interested in, sit on the bikes and do some test rides. Figure out which gives you the riding position, ride and handling you are looking for, then decide how much money you want to spend and which level in the range you want to get.


Looking for suggestions on a mostly-road mixed-use tire

Product replacements are considered off-topic, so I will discuss tire characteristic trade-offs for your riding environment:

  I'm riding tracks that are 90% on-road, 5% poorly paved cracked roads and 5% gravel, dirt, chips, etc. No mud. Basically: ride 5km to a park, ride 1km there, ride back.

Because you are not dealing with mud, a slick tire or nearly slick tire will work quite well for the short sections of gravel you are encountering.  While many people prefer knobby tires, these are not necessarily required:

  The truth is that on gravel, knobs don’t make any difference. Without semi-firm ground to dig into, knobs can’t do anything. When you slide, it’s because gravel is sliding on gravel, not because your tires are sliding on the top layer of rocks.

  Why We Don’t Make “Gravel” Tires

The above is especially true for larger volume tires, example 700x40c tires at low pressure, which float on the loose gravel, providing traction through a large contact patch. (Your cross bike may or may not fit such large tires).  That said, this isn't the whole truth.  Often gravel roads can have a thin layer of loose on hard pack, here knobs will dig through the thin layer of loose to hook up on the hard packed. Slicks will not.

Slicks however can have a surprising amount of traction on dirt, as long as you don't push the tire to the point that it slips. Kinetic friction, friction when sliding, is in general a lot lower than static friction (the friction mode tires usually operate on, you roll, you don't slide).  Furthermore, this scenario is made worse as the small rocks act as ball bearings when sliding and there slick tire has no edges to try and hook up on irregularities while sliding.  Here knobby tires will be more controlled in a slide as all the knobs provide lots of edges, and edges provide more traction when sliding.

However your ride is only 5% gravel, a relatively small proportion of your route, so running a knobby means that 95% of your ride essentially sucks as the knobs rob speed and squirm on the pavement.  As such, the most fun will likely be had if you optimize for the 95% paved.

A higher volume slick will also work well on the poor paved roads as it lets you run lower tire pressure before 1) handling declines and 2) you bottom out the rim.  Lower pressure means a more comfortable ride in the rough road. But similar to gravel, this is a small percentage of your ride, so if doing this adds rolling resistance in the other 90% may not be ideal.  This really depends on the quality and construction of the tire (more below).

Your current tires are probably a good fit for your current ride. The only thing I would consider is that any tire with a descriptor such as "Hard-case" will be a stiff ride, which means that either comfort or speed (or both) will be sacrificed. A more supple (easier to bend) 32 tire will probably be faster. That said, unless you are running tubeless with sealant you then have to balance this out against higher probability of a puncture. (Hard-case usually implies puncture protection).

Finally, and most importantly, your rides are currently quite short (i.e., 12 km).  On shorter rides (i.e., under an hour), I am personally hard pressed to notice much difference in tires. These differences really start to get noticed when you are on longer rides (e.g., 2-6 hour rides).


Aero spokes strength on a family bicycle

I don't think you'll have a problem. Aero spokes are no less strong than regular double butted spokes. I use them for downhill riding and whenever one breaks (due to bad handling, loose spokes or extreme impacts) it is never on the bladed flat area. They'll either break close to the nipple or close to the spoke head.

Also note that usually spokes break one by one and never all together. So even in the rare scenario that one breaks (probably because they where too loose) the wheel will be able to continue riding normally and you'll replace it and retighten as soon as you can.


Is it considered rude to draft other random cyclists?

There was a post on this subject on The Guardian Bike Blog.

I think there are a couple of issues with drafting random cyclists:

it could be unsafe, particularly if they don't realise you're doing it.
some people will object to being drafted - it can be considered an invasion of your personal space.

I think your best bet is to ask before drafting, then there's no problem.


Where to park a bike during a year for free ? (in the Netherlands?)

Probably your best bet if you want to park them is to meet someone with a large shed who'll put the bikes up for you.

If you make the finance/convenience tradeoff I think selling the bikes after your stay and getting new ones when you return might be a better option, but I understand the convenience of having the same bike.

I can think of several options that don't require you to find such a nice person but they all have their drawbacks:

Park them somewhere on the street. This would work for an EUR 50 bike, just fix them to something with a good lock somewhere out of the way. However, the dutch climate won't be nice to your bike.
Park them in any public bike parking area near a big train station. Most of them have a roof these days, and they are free. However, in the bigger cities and all university towns you're not allowed to leave your bike for more than a few days at most, and this is actively policed. So chances are your bike will be removed under this rule. If this happens you have a few months to pick it up from the depot before they sell it off.
Park them in a "private" bike parking area near a big office building. This might be a reasonable option if you are willing to do a bit of sneaking to get in. Most of these bike parking areas have room to spare, so two exta bikes won't bother anyone, and if you park far away from the office entrance no-one will notice the bikes standing there all the time. Downside is that these buildings are usually not in very central locations. You could even ask the concierge if he'll let you park the bikes for a few months (with the risk of him turning you down where he wouldn't have noticed the bikes if you hadn't asked).

In all cases the property owner or the local city government is within its rights to just remove your bike if it is deemed to be in the way or a wreck, which is always a risk for a EUR 50,- bike.


Dakota 20 - How do you show remaining route distance on dashboard?

Page 19 of the manual states:

  The Trip Computer displays your current speed, average speed, maximum speed, trip odometer, and other helpful statistics. Touch a field to change what is shown in that field.

If you've touched each field and remaining route distance is not an option, then I think it's safe to say that including this information on the dashboard is not possible. That said, the compass mode and possibly the navigation mode seem to be able to include this information, though they may leave off other data that you care about.


My tire was slashed. Replaced the inner tube, but should I replace the tire as well?

You already know the answer to this question.
Slashes in the sidewall tend to open up as the pressure from inner tube is pushing the tire further apart. If you're lucky you might escape with a simple pinch flat. More serious problems include:

the inner tube pushing through the sidewall rubbing on the frame or fork causing the inner tube to burst like a balloon.
the inner tube removing the bead of the tire

Either of these I wouldn't want to happen at speed.


It may be worth glancing at this more detailed answer that discussed how aluminum rims were constructed. But in brief, aluminum rims are first extruded in a flat bar, then they’re cut and rolled into hoops, then the ends of each hoop are joined. One method is to simply pin the ends together, and you’re looking at the seam where the ends were joined. Alternatives include welding the ends together. Basically, this is there by design. Look in the corresponding location on the other rim and you should also find a seam.
The seam looks too straight to be a crack. If you hit an obstacle, a more common failure mode would be for the rim’s bead hooks to get dented or to buckle.


SRAM X4 MTB Rear Derailleur H-Limit screw maximum open, but still on 7th Cog?

First thing to check is if your rear derailleur is bent. If that is not the case, check the cable tension is not too high. Is the shifter acting funny (like hard to shift)?

See this link to see how to do adjustments: http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur


Full suspension bikepacking. can it be done?

There are rear racks such as the Thule Tour Rack which attach directly to the “seat stays” or fork of a full suspension MTB:

I’m not an expert on MTBs and don’t own one myself, but apparently a disadvantage of this solution is that it makes the luggage part of the unsprung mass which should be as small as possible. However since you are probably not riding demanding trails with 20kg of luggage attached I doubt it’s going to be much of a problem.


What is the difference between Time-Trial and Triathlon bikes?

They are very similar but have to follow different certification rules. For example, under UCI regulations the saddle of a TT bike must be at least 5 cm behind a vertical line drawn through the bottom bracket (cf. Rules 1.3.011 to 1.3.025), there are constraints on the size, shape, and orientation of frame members, and so on. Triathlon bikes are certified under a different set of rules depending on the race being run and allow a greater degree of integration of components (such as water bottles that are designed to fit within the frame in a way that enhances aerodynamics). Currently, any UCI-certified TT bike can be used in a triathlon but not all triathlon bikes are allowable in UCI-sanctioned races.


What is this device attached to the seat-tube?

It appears to be a clamp-on pump peg that got moved down out of the way either intentionally or from coming loose.


Summary: it's hard to make a light that reliably turns on only when the brakes are used.  Most cyclists who want brake lights buy rear flashing lights because they're cheap and ubiquitous.

Ignoring cost, to work well a brake light on the back of a bike would need to be paired with a constantly on, non-flashing light, purely so that people who saw it would recognise it as a brake light. Otherwise it's just another blinking light on a bike. Then it needs to be daylight visible, or no-one will see it.

From my experience with rear lights, 200 lumens is about the level you'd want from a brake light. My always-on dynamo rear light is about half that and while it's visible it doesn't really stand out. In other words, it makes the bike more visible without being too bright. But for a "hey, I'm stopping" light, you want more than that. So the combination of a 200-500mW always-on light with a 1W or 2W "BRAKES!!!" light would probably work pretty well.

Unfortunately most super-bright LED rear lights are designed to overdrive the LEDs in short flashs, but for a brake light you want a solid 2-5 seconds of on time. Which means bigger, more expensive LEDs. And also a bigger, heavier battery to drive them.

The sensors are also challenging. SeeSense have done a lot of work on accellerometers in bike lights and from using their light, braking detection is ok but not brilliant. If I  hit the brakes to reduce the impact of hitting a pothole, for example, the light seems to got into "holy shit" mode instead of braking mode 90% of the time. Which might be ok for a brake light, 5 seconds of braking mode in that situation is fine. But it means that I'll get 5 seconds of braking mode when I bunnyhop a curb or bounce a speed bump too. Which isn't really "braking" as I think of it - I'm definitely not slowing down at that stage. So you probably want sensors on the brake levers as well (the accellerometer is built into the CPU that runs the lights). Which means wires and fiddly mechanical bits. I dunno, that seems hard to me, you have to cover road bikes with integrated electronic shifting right down to basic V brake levers. Sounds expensive.

To get an idea of costs, look at some of the KickStarter bike lights. It seems to cost about $100 to get a light to market. Which means hardware costs of about $25. If we double that because we're using, say, two 18650 LiIon batteries (18Wh) instead of one, CR123/16340 battery (half-16550, 4.5Wh) and a 0.5W RED LED as the primary light plus a pair of 1W LEDs as the brake light... ok, maybe triple it. So you're looking at a light that will cost about $200-$300, assuming the sensors are cheap and reliable. Cheap means pure accellerometers, like the last light in your list.

Which makes them "something is happening" lights... just like any other blinking light on the back of a bike.


Rotor does not fit between pads after replacing the pads

Maybe the entire system was bled with the pistons not in its full retraction. So when you push in the pistons, you're actually just applying pressure to both the master cylinder and the diaphragm of the open system structure. (and compressing the air inside, if there are any)

Try opening the bleed port and screw in the oil funnel before pushing the pistons in. While you're at it, try to squeeze out any air that could be in the system. Then carefully plug the funnel, unscrew it from the port, and close the port.

Try squeezing the brake lever a bit but not too much and see if you don't have any sticky pistons. If they're stuck, you can follow this video:


Shimano PF-M545 pedals Mavic Alpine All Mountain Shoes how to fit the cleats

Turns out that there was a male screw thread inside the female and I needed an allen key to get it out. (I had to go to bike shop to learn that, though.)

After that point the rest was clear sailing, following the instructions closely, and watching some online video tutorials about it.


Looking for coat: shell front, fleece back

Things like this are out there.  Look at the suppliers of mountaineering clothing as well as cycle manufacturers for innovative use of contrasting fabrics for ventilation.

I have an older model of this jacket:  http://www.patagonia.com/us/product/mens-wind-shield-pullover?p=24991-0-425

It treats me pretty well--wind-proof front, but with fleecy breathable arms and back.

I believe that, in Canada, MEC carries Patagonia clothing.


How many sprockets can I fit on a crank?

4 chainrings seems to be the feasible limit:

http://abundantadventures.com/quads.html

However if you add an internal planetary gear setup, A 100 speed might be possible if not practical. Here's a 63 speed bike.

https://sheldonbrown.com/org/otb.html

There are internally geared 2speed front axles.

https://www.alphabent.com/internally-geared-cranksets

So in theory 8x is possible on the front, 12 on the back gets you close to 100. You could go 14 in the back with a Rolhoff hub and get over 100.

I suspect such a bike would self-destruct in a very few miles though. Internal gear systems aren't engineered for the kind of forces that gearing could generate.


You don't say where in the world you are, so it's not clear what the traffic regulations are. I'm in the UK, so I'll assume UK-like regulations – bicycles are allowed to use the vehicle lanes even when there's a cycle lane and bicycles are basically supposed to act like cars.

First, regardless of regulations, you've missed option 3, which is to slow down to a speed where the cycle lane is usable. You don't say exactly what the problems with the cycle lane are but, unless they're so dangerous that the highway authority needs to have fixed them yesterday, you should be able to slow down for them. By approaching what you know to be bad sections of the cycle lane at speed, you are severely limiting your options.

Second, you mention motorists being surprised when you enter their lane. In jurisdictions that I'm familiar with, signalling a turn means "I intend to manoeuvre when it is safe to do so." In particular, it does not mean "Please make space for me – I'm gonna turn!" If you are signalling, it would be nice for somebody to make space for you, but that is not an obligation and a car rapidly braking from its 40mph to your 20mph is asking to be rear-ended. If your lane change is causing surprise, it suggests that your manoeuvre wasn't safe and that you were using your signal as a request for space rather than a notification of intent. After all, if there had been enough space for you in that lane (i.e., a long enough gap in the traffic), motorists wouldn't have had to react to your presence at all.


Rear brake pad clearance problem on '06 Specialized Langster

Well, I went ahead and ordered some Shimano 105 dual pivot calipers. Unfortunately the rear caliper arms will not clear the seat stays. There's just no fixing it as far as I can tell. If I put on additional washers, the fixing nut will not thread onto the main mounting bolt far enough. I tried several sizes of fixing nuts and none of them will work.

I hope that I will be able to find some other brakes calipers that will work. If you know of any, please let me know!

***Update: I solved the problem by ordering a SRAM Force brake caliper set. Those calipers have a lot more clearance between their arms and the frame, and the bike shop filed down the main fixing nut so it will fit inside the rear brake bridge.


Rear derailer/chain skipping/shifting issues

If you feel clueless about bike maintenance or troubleshooting, the good news is that there is quite a lot of good content on this subject available, which makes it easy to learn how various bike systems work, how to perform regular maintenance and adjustments and figure out problems. My favorite is Park Tool Company's site and YouTube channel. They have a series of videos that deal with derailleur systems:

            . There are other guides available. These are easy enough to find by googling.

To address your specific problem: because you say you feel excessive resistance at the shift lever, I would initially check that there is no impediment to the free movement of the shift cable and derailleur. There may be a problem in the cabling, at the rear derailleur, or in the shifter itself.

The derailleur auto upshifting (to smaller sprockets) after downshifting (to larger sprockets) may indicate a bigger problem with the shifter. If the chain is only upshifting one sprocket it may be that derailleur is not moving the chain far enough and the chain is falling down to the next smaller sprocket. If the derailleur auto-shifts several sprockets I would suspect that there is a problem with the shifter and it is not holding on to the shift cable properly.

Things you can do to diagnose the problem:

Get the rear wheel out, observer the derailer and run the shifter through its range properly. Does it move at each shift and through the full range? If not it points to a problem with the shifter.
Manually inspect the cable run to make sure they are no snags, twists or kinks and that the housing is properly in each cable stop.
If you have exposed cable rather than full run housing: shift to the highest gear/smallest sprocket, grab the shift cable in different places on its run and pull outwards from the frame to actuate the derailleur to its innermost (low gear) position. If you feel resistance or roughness there is an impediment 'downstream' from where you pulled the cable.
Disconnect the cable from the derailleur. Manually check the derailleur will smoothly sweep through it's full range, outer limit to inner limit, you should of course feel spring tension but no roughness.
With the derailleur still disconnected, manually put a little tension on the cable at the derailleur end (you may have to use pliers to grip the cable, but don't crush it), run the shifter through it's range. Do you still get resistance at the shifter? Does the cable move at the derailleur end at each shift?
If the above does not show up a problem with the derailleur or cable run, you will want to look at the shifter itself. I'd want to try to see if the shifter is slipping back to higher gear positions after being shifted to low gear positions. If you can, get hold of the cable as close to the shifter as possible in it's run, put tension on it and run the shifter from high to low gears, it should pull cable the cable in in increments. if you can pull the cable back out out, the shifter is probably work out or broken and will need to be replaced I'm afraid.


Does a carbon frame need two-bolt seat clamp?

On carbon frames I've used, they have had a single bolt clamp like this one, so it should be fine. Personally, I'd like to use a slightly bigger clamp and one of those rubber size-decreasing rings to avoid cracking the frame. If in doubt I'd phone up the manufacturer of the frame and ask!


As a number of other posts have pointed out, your best option is to get yourself a proper repair stand. They are not that expensive, and you will find that you and your friends all get good use out of it. But, if you are determined to do it on the cheap, here are a couple of techniques that worked for me before getting a workstand:

Turning the bike upside down - this is really simple and requires no additional purchase. You may want to look at putting some form of drop sheet down underneath the bike both to protect the saddle and handlebars, and to catch drips. This works well for pretty much any work on the wheels or transmission.
A bike storage rack or car rack - obviously these are already designed to hold a bike, and you may already have one to hand.
Suspending the bike with rope - If you have some overhead attachment points, this can work, however it is not going to provide an immovable mount for the bike - you will still need to hold the bike against the force of your tools when fastening and unfastening things. A trick to be aware of is to use two suspension points overhead and two on the bike (head tube and seat tube) otherwise the bike will spin in the air.


Does it harm if my bike to leave it in a workstand for 2 weeks?


You absolutely need SRAM shift/brake lever units. SRAM road shift/brake levers are compatible with their MTB derailleurs and come in a 1x11 version.

Trying to mix Shimano and SRAM will just be a huge headache. I'm not even sure there is a shift cable pull converter for that.

Hydraulic vs mechanical calipers is up to you and your budget.

Something you should be aware of is that flat bar bike frames are typically longer than drop bar frames, because flat bars place the rider's hands closer to the head-tube than drop bar hoods or drops hand positions do. Check your bike's geometry to make sure you wont end up with too much reach.


Is it possible to glue or patch tire sidewalls?

You need to "boot" the inside of the tire with a dollar bill or purpose-made tire boot or some such.  You shouldn't glue the boot in place, but you may use a small dab of glue to keep it from shifting while you install the tube and inflate the tire.


What is causing an intermittent side to side wobble of the rear cogs?

Check:

Freehub body: no play radially? laterally? Try to reproduce it when lightly apply the brake (with barrel adjuster) and hand-pedal while the bike on stand. does it still wobble?
Cassette spacing: remove the cassette and see if there is any irregularities in the spacer.


I’m pretty sure the wheel size you quoted is what’s written on your tires i.e. ISO 622 rim (aka 28”, 700c) with a 37mm wide tire.

You need the internal width between the flanges of your rims to know what size rim tape to get. This is easy to measure with the tire and tube removed.

I.e. 22-622 rim tape is for ISO 622 diameter rims with 22mm internal width.


Fitting 1.5" tapered fork in a 42mm head tube?

Crane Creek makes a headset that will solve this problem. I've used it on my MTB and it works well. It does slightly increase the stack height.

Do I need a tapered head tube to use a tapered fork on my bike


Pulsating and screeching after changing disc brake pads

Unfortunately you have done nearly everything possible. Some brakes/forks/frame/pads/disc combination just do not work nicely.

The one remaining thing you have to change is the disk. As the pads bed in, they lay down a thin layer of pad material on the disk, it is the microscopically thin layer that allows the braking to occur. If the bedding in is done poorly, the layer is uneven, and further bedding in may not even it up. Changing pads means the material laid down on the discs may not bed in with the new pad material. Sanding the pads disrupts (I won't say removes) this microscopic layer, allowing a new layer to be laid down when bedding in again. If the new layer is laid down evenly, the brakes will not squeal.

A final option that may (or may not) work it to change the disk itself. The obvious choice is a different type, but even this is no guarantee of quite brakes.

You really have three choices - go back to you old pads (They may now squeal), tackle the disk (sand or replace) or live with it.

Use a fine (400 or even 1000 grit) wet and dry sanding paper. This can be done with the disk in place, but is easier if you remove it.  There is no guarantee this will work, new discs are sometimes the only thing you can do.


Trying to find a FC-M371 crank on line but no luck for my part of the world (Australia, New Zealand, Pacific Islands)

That is a standard square taper BB, so an square taper BB with suitable sized chain rings will replace it.  While 9 speed would be ideal, if the best chainring match you can find is 8speed it will work reasonably well.
As far as chain ring sizes, you do not need to stick with 44/32/22.  If you go larger than 44, you might need to lengthen the chain. If you increase the difference between the 44 and 22 (22), you may have problems getting it to work well.
A suitable low cost replacement might be FC-M311, which is commonly 22/32/42 - a slightly lower top gear.
Without offering recommendations, Wiggle and Chain Reaction in the UK happily supply into NZ (as long as its not Shimano) , along with JensonUSA in the US. You LBS will be able to source a suitable replacement very easily, and unless you have access to a crank puller, probably cheaper to get them to install it.


Warranty on lock damaged during attempted theft

Warranties exist to protect you, the consumer, against defects in materials or workmanship, not against deliberate damage. The purpose of a bike lock is to help avoid your bike being stolen, so if it has prevented a theft of the bicycle then it has done its job well.

Perhaps you can ask Decathlon and report back to us by answering your own question for future readers, that would be most useful.

You would have to explore if the damage is covered by any of your insurances, check local laws on any time limits to report the attempted theft by (to police etc).

Sometimes lock companies will offer private schemes to replace stolen goods, like this number one Google hit, but you would probably know about such a scheme if it was advertised on your product and you'd likely need to have registered the purchase.

In this case, you bought a lock to protect the bike, and it worked, which is great.


Is storing bikes in an enclosed trailer a good idea?

So long as the trailer is reasonably weather-tight it shouldn't be a problem.  Since there's nothing in the trailer generating humidity, no significant condensation will occur, and, within reason, temperatures won't hurt bikes.  (The only caveat would be that you maybe should have some vents that can be opened if temps rise above 90F or so, so that temps don't get over about 150F inside.)


For a generator you will probably want two sets of gears. Cyclists normally pedal at about 90-110rpm, and getting a small generator to work efficiently normally means spinning at 1000's of rpm. I used a "drill pump" to make a pedal powered pump once and that was designed to spin at 1800rpm. But it used 500W or more at that speed, so I spun it at about 1000rpm using about 200W and that worked fine. Unfortunately I lost interest in taking photos after building the first, single-stage version.

Most of the bicycle generators I've seen use the bike wheel as the second gearing stage, typically having a generator drum 100-300mm in diameter for a ratio between 2 and 6 to 1. The bigger the drum the lower the ratio, but the less tyre deflection so the higher the tyre/drum efficiency.

Depending on what tools you have (mostly, do you have a lathe) you can either use the large cog on the cassette to drive a second cassette, or make an adapter to mount a full size chainring on the cassette. If you get a steel cassette and chainring you can just weld the chainring on, and it will probably not deform too much.

Doing that lets you have a road bike first stage with a maximum ratio of 50T:12T or ~4:1. If the cassette is a wide range one off a mountain bike it could be 12-36, say, giving you a 36:12 second stage or 3:1. That's 12:1 overall, so your 100rpm input becomes 1200rpm output.

You can get the same ratio with a single stage but it will be big and expensive. Assuming a 12T small cog, you will need a 144T chainring to get the same 12:1 ratio. There's one on ebay for $US500. A friend of mine sells large custom chainrings in Australia and could make you a 144T one, but a 90T one costs $AUS200 (about $US150 in April 2016).

I think the important thing is to start with the generator you want to use and work out its ideal spin rate. Then work backwards to the gearing. I suggest leaving at least one derailleur in your final build so that people can vary the gearing a bit to get the most comfortable combination of pedalling speed and load. Varying the generator output has much the same effect if you can do that.


Need help identifying Industry Nine part

Flangeless front hub shells.

Standard OLD for front hubs is 100mm - which these would be with bearings and axle installed.

The array of holes at each end are for attaching spokes.


Replace solid axle with quick release on Fixed Gear

This is easily accomplished, simply replace the axle from your wheel with a QR axle, at most you may have to cut an axle/skewer to length and maybe cut more threads if you can't find an axle and skewer with enough thread on it. But you'll need to be comfortable with cutting metal and have the right die set.

If you try shopping around for a 120mm rear QR axle, you'll have better luck looking for a complete hub and just parts it. They're not super common though, and not cheap...


Which way does this ring go on the left crank of this Shimano deore hollow tech external bottom bracket crank?

The side that you say has been rubbed silver by friction is like that on a new ring (I've got two, bought from SJS cycles). From what I can tell from other posts it's intended to stop water and crud getting into the bearing. That would suggest that the non-silver side, the ridged side, should go next to the bearing because this is like an oil seal (although there appears to be no rotational movement between the two). The silver side goes into the recess on the crank arm. The washer is a tightish (waterproof) fit on the spindle so together this should stop water getting into the bearing from the spline on the crank arm.

Just to clarify, there is probably no rotational movement between the crank arm and the face of the bearing - the inner part of the bearing appears to be free to rotate with the arm and the spindle. However, there must be a seal within the bearing to seal the rotating inner part from the fixed outer part.


There are a few things that are going to cost you more, simply because you are not used to working on a bike and will have to have them done for you.

Tuneups - You generally get one free at about 30 days after you buy the bike. Mostly this consists of readjusting the derailleurs (shifting mechanisms) and the brakes as the cables stretch. Tuneups in my area (Phoenix, Az) cost between $50-75 depending on shop and any replacement parts. Avg 2-3x per year
Tires/Tubes - Ongoing. I recommend a tougher tire such as gatorskins ($50 each) for training, and then switching to a performance tire (Conti GP 4000 - $65 per tire) for racing. Tubes range from $7 to $15 each. I would just stick with butyl, even latex for racing is a bit overkill to start. Avg 6-8 tubes per year, 1-2 tires (per wheel).
Chain/cassette - $50-100 per cassette, $20-50 per chain depending on quality, plus shop cost to install/change. 1-2x per year depending on maintenance and mileage.

Those are the major ones that I would consider regular expenses. Other expenses such as new rings for the front crank happen, but they are much less often. Same with changing out the seat. Now, you have to start looking at your own personal maintenance habits. Are you going to be cleaning and oiling your chain on a regular basis? If so, then you can add cleaning/degreaser solution, and chain lubricant to your ongoing costs. Poor maintenance/dirty drivetrain will cost you both power and lifespan of your components.

Other incidental costs (Generally less than $10 for item cost, plus possible shop time for install) are brake pads, cables, bar tape, cable housing.

Now, you can get top of the line components and wheels, just realize that your ancillary costs will go up as well. For example, if you get performance wheels with carbon brake tracks, then your brake pad cost goes up from $10 to in the neighborhood of $50.

Finally, the initial cost for tools and other items to be able to do your own work is high (A complete home type set of park tools can be assembled for $100 on the sparse side to $200 for almost everything needed), the payoff is that you save shop costs forever. It's all a matter of what you personally feel comfortable taking on.


Why dual pivot brakes, not longer brake arms?

The single pivot sidepull design requires a fairly wide pad gap at the rim in order for centering to not be too finicky. It's essentially the widest of all common rim brake designs. This is due to the spring design's two sliding contacts, as Jobst Brandt writes about here. The contacts are hard to keep at the exact same level of friction, and any disparity takes the brake out of center. You need a wide gap to compensate, at least for a normal person not fiddling with their brakes all the time.
You can't just add longer actuation arms to make the same design more powerful because it's still the same human hand at the lever end. If you want the pads to be able to touch the rim, then longer actuation arms with the same pad gap would require either shorter lower arms, which you can't do because there's a tire there, or a lever that pulls more cable. You can make the lever pull more cable, as in a v-brake lever, but note that v-brakes have a much smaller pad gap. That's why they can have a lever that generates much less mechanical advantage. Do the same thing with a hypothetical long-armed single pivot and you get a brake with very low power.
In other words, all brake designs are bottlenecked by the input force. You can't then have one that's also bottlenecked by pad gap and have it compete on power with ones that aren't.
What amount of pad gap should be designed in to the brake to overcome the centering issues is subject to both opinion and potential design advancement. You may even disagree with the premise that this is a design limitation, and that's fine; every real advancement in component design does. If you made a single pivot brake that could happily run with the pad gap of a dual pivot, then yes you could increase the arm length to get the mechanical advantage of a dual pivot. There's presumably some way of doing it with graphene.


First got though  this park Tools guide

If you are still having problems, I suspect the derailleur cable. Either replace it (best option as they are cheap) but its worth flicking the outers off the bosses, cleaning and lube as much of the cable as possible.  If this improves things, a new cable may be needed.

If this does not help you probably need to check the derailleur alignment. unfortunately your derailleur has an integrated hanger so its harder to check. Fortunately, as its only 5 speed, accuracy is not so important. If noticeably bent, you can straighten it using an adjustable spanner, but will have trouble getting it accurate.

Another possibility is the derailleur is flogged out, although in my experience kids don't change gears enough for this to happen


What is the matter with this Shimano disc brake lever?

If you want to use these brakes 1 fingered, I would recommend moving them to the inside of your shifters to remove the overlap with your middle finger.

I have all my brakes set up like this and it works great.


Should I have a spare cassette or a spare wheel?

It's a personal choice. If you're going to run the same tires, then just go with a spare cassette. It's pretty easy to swap them out, so I don't see that as a big deal. However, If you're going to have different tires and a different cassette, then I'd probably opt for the different wheelset. If you need a more durable wheelset for touring, you might also consider a separate wheelset.

I tend to have a road and off-road set of tires for my cross bike. Since it's a lot more work to switch the tires each time I want to ride different types of terrain (and want a slightly larger range on the off road set), I prefer to have a separate wheelset.

It only takes a minute or two to swap a cassette, and also gives you time to get the other one good and clean while it's off the bike.


You need a spoke key of the correct size. See Which size spoke tool. Currently size 14 for some discussion - the short version is either visit your LBS and buy the size that fits your spokes, or just buy the three most common sizes.

Using a screwdriver is unlikely to work - wheelbuilders use them in the very early stages when the spokes are very loose, but as soon as a little tension goes onto the spoke the nipples are impossible to turn that way.

Edit: a couple of links on how to true wheels. If you're willing to spend money The Bicycle Wheel is pretty definitive and it's quite a short book. It's hugely better than anything I've seen on the internet.

And your LBS should have a pile of spare nipples for their wheelbuilder(s) to use. They're only a few cents each, but buying retail like this probably 10c-20c is more likely.


Can park tool bbt-59 take off ultegra sm-bbr60

The BBT-59 is definitely a correct choice in tool to use. However, you shouldn't ever break free tight things with a torque wrench. Ideally you would never use a torque wrench in the loosening direction. It's a bad practice. If you know the thing you're loosening is within the torque range of the wrench and its current setting you can kind of cheat there if you really want to, but loosening arbitrarily tight things like a BB cup is not a job for a torque wrench. Use a breaker bar.

The new Park external BB tools (BBT-59 and BBT-49) have inexplicably broken from the tradition of such tools having large external wrench flats for a big adjustable wrench, such as their and everyone elses' first generation socket-type external BB tools. Having external wrench flats allows you to play the trick of using a QR skewer or bolt plus some big washers to clamp the tool to the cup so it can't slip in case you're dealing with a tight or stuck cup. So instead you just have to position everything so you're using your body to keep the tool pushing hard inward as you turn it. If there's any thought process here at all, they probably did it this way because they made them out of aluminum so they can be non-marring, but didn't want people trying to turn the outside at high force with adjustable wrenches, so they eliminated the option. But if they cared about that they could have found a way to create a non marring contact surface and a steel body, same as using the freebie plastic adapter tool that Shimano includes with these BBs if bought aftermarket.

As for how to get it off, as in the comments make sure you're turning the right way (ISO BB shells have reverse threaded right cups). Usually the technique for a difficult one of these with that tool would be bike on the ground, knee or shin pressing the wrench inward against the bike to prevent slipping, tool started at around 45-60ish degree angle across front triangle, and try to find a way of putting all your body weight into it, or even use your foot. Having someone hold down the back wheel can help.


Where can I get a Job that involves bicycles?

The "dirt" magazine (137/july 2013) has a small article on that. Possible jobs listed are:

working in a bike shop
pro rider
writer (in mags, web)
photographer
guide (riding instructor)
industry related (designer, marketing)

So, you'd need to find out which of the above you are best at and start contacting people, sending cvs etc.


From a naïve geometry point all three options are equivalent.
For real systems material properties and 3d geometry become relevant. For instance, your model (A) could not be made with a single piece bar. The double 90 degree bends needlessly increase stress.
On the level of one dimensional line figures there's no reasonable answer possible. To answer this question you need the actual dimensions and materials in a CAD model and then run an finite element analysis (FEA).


What is the difference between a TREK 7.2 FX and a TREK 7.3 FX?

This higher numbers are upgrades.  Trek website

Upgrades on 7.3 FX from 7.2 FX

IsoZone grip and handlebar system
Bontrager Race All-Weather Hard-Case tires
Alloy FX Fork


Freewheel not engaging when temperature below about -20c/-4f. What is freezing?

If the pawls will not engage the wheel will not engage.

It could be moisture freezing.  More likely the grease is just more viscous (sticky) at lower temperatures.  If you really have a freewheel (not freehub) then it is likely not serviceable.  If it is serviceable then break it down and clean it.   There is grease for bicycles and also low temperature grease.  For sure you do not want to use a generic axle grease that is designed to handle high temperature.  Use a light (low temperature) grease and accept you will need to service it more often.  Use a lot to not give moisture as much room.

If it is a non-serviceable freewheel you might free it up with WD40 but that is not really a long term solution as WD40 is more a solvent than lubricant.

There are variations but this is the basic design


Should I replace the bent Derailleur hanger?

Yes, replace it. It's too bent to be straightened, or will be weakened considerably if it is straightened.


Well, there are a ton of adjustments you can make, but sometimes a bike just won't fit someone. You may want to look up "bike fit", though this is something you probably should have done before you bought the bike.

You can:

Move the saddle backwards
Move the saddle up/down
Change the angle of the saddle
Change the stem height
Change the stem (to get a different length/angle)
Re-angle the handlebars

I'd start with moving around the saddle, since doing anything other than re-angling the bars may not be an option.

The saddle height is adjusted by a bolt or quick release lever where the seatpost goes into the frame. The rest of the adjustments are normally controlled by an allen key on the bottom of the saddle, where it is clamped into the seatpost. You can see this video for example.


How much faster can i go after moving from 2x10 to a 3x10 gear setup?

Well, if you switch to 3 in front, and then make it a 52/38/24 set (equal steps) then your theoretical new maximum speed would be:

[new max]=52/38*[Your current max]

Currently at your top speed one revolution of your crank leads to 38/11th of a revolution of your rear wheel. This will become 52/11th or about 1.37 times as much.

This is not the whole story however. You probably know that wind resistant is much more of an issue at higher speeds than rolling resistance. So (unless you are really strong) your actual maximum will be quite a bit lower than the theoretical maximum calculated above. This tool allows you to set your speed or power output and calculate the other. If I assume your current max as 30kph, your bike weight at 9kg, your weight at 70kg (don't be offended, I'm just guessing), and you are on MTB tires and in the "hoods" position (whatever that is) then your power output at that speed would be about 220 Watt. With the extra chainring in front your theoretical maximum speed would be 41.1kph (all other variables being equal) but to attain it you would need to about 470 Watt! More than twice as much!

Obviously in your current situation you are not pedaling efficiently at your maximum speed because you are spinning your legs like crazy, but a 1.4 times speed gain is probably too much to hope for. As a test to see where you can get you could ask your friendly LBS owner if he'll lend you a bigger front chainring for a test ride and see if you can find out from that at what point you max out.


Friction shifters eventually need to be taken apart, cleaned, and re-lubricated to solve the problems you mention. Be very careful to keep the parts in order. You'll find advice on the above mentioned other thread not to lubricate them, which is wrong. All the surfaces should get a thin film of oil or grease, ideally something that doesn't harm plastic presuming your shifter has plastic washers, as most do. Using a mild or medium strength Loctite is optional but is a good further safeguard against slippage, and won't keep you from loosening them on purpose. Some people use beeswax as a substitute.

The plastic washers inside can degrade, which wouldn't be surprising on a 30 year old bike. If so you probably just need a new shifter unless you want to get crafty and find or make new ones.


What considerations are there around replacement of cable-actuated disc brakes with hydraulic-actuated calipers?

If the brake lever is integrated with the shiftier, you will need a new shifter.

Cable run for Hydraulic will be continuous, and you wont have C-Clip mounts. You will need to use zip ties to hold the cable to the frame. Functionally there is no problem with this, how you feel about this depends entirely on if you prefer form or function.

MTB Caliper mounts have been standard for 15 years or so (Road has a different standard introduced by shimano in 2010 ). In most cases you will be able to unbolt the mechanical calipers and bolt on the new ones, however some calipers are aimed as a different minimum rotor size. This means you may need a new adapter depending what you have and what you get. As long as the new caliper minimum rotor size is not larger than the rotor you have, you can get an adapter to fit.

I would think about installing new rotors (although $$ is a consideration). The old brakes were not expensive, so the rotor won't be the best quality, new rotor would keep everything matching.  It may make no difference but might help with longevity and reliability (e.g. if they are warped).


Finding the right length of chain lock for my road bike

I faced the same dilemma a while back.
Getting a big chain implies carrying way too much weight around. Even a small, good bike chain is pretty heavy and can easily be 1/3 the weight of your bike.

The best way to protect your bike and be able to carry the locks around is to have a chain or a U-Lock, and with these you can easily secure your frame and a wheel, and then use a small cable like this to secure the other wheel. One wheel is less protected, but a substantial part is under a good lock and the weight is not too bad.

From these I actually prefer a small chain to a u-lock because it is easier to lock the bike to a tree for example, but if your city is bike friendly a u-lock offers very good protection and is much more manageable.

When buying locks keep in mind price usually means security. I recommend you check the independent tester of locks Sold Secure. They have a catalog with different locks they have rated.


It sounds like you have a kind of injury that is common in skiing. What happens is the ski pole handle gets trapped under the thumb when falling, causing the thumb to bend the wrong way. You can find supports such as this one. I can't speak for that one specifically, but if you look up "skier's thumb" on the internet you should be able to find lots of information on the injury and ways to prevent it.

Also, something like a rollerblade wrist guard might do the job, but I'm not sure how well you could grip the handlebars with something like that.


That's just a poor weld. Notice there are other deliberately drilled holes in that area so an extra one is not a problem.

Clicking in the headset area is much more likely to be flex between the steerer and stem, stem and bars, or possibly the headset races pressed into the frame. If the click happens as you go over a bump or change force on the bars through pedal strokes that would point to those interfaces as a culprit.


The stock advice is to put zero reliance on your ears ever. There's this issue, there's the related issue of wind direction keeping you from hearing a car even not at high speeds, and there are extremely quiet cars. Basically the choice is look back a lot and get good at it or use a mirror.


Fixie/single speeds have the same measurements as any other bike.

Most fixies/single speeds have geometries that are like old road bikes or hybrids depending on how they're built (obviously a fixie built from an old road bike will have an old road bike geometry!). So, you need to take that into account and preferably try the bike before you buy it. You may find you want a longer top tube or shorter top tube or whatever.


Cycling into tunnels with claustrophobic person

This is how we did it, for all tunnels longer than 150 meters (ranging from 200 meters to 4 km):

before the entrance of the tunnel, the leader slows down or even stop, allowing the follower to get closer
after entering the tunnel with lights on, regardless if there is a cyclable sidewalk or not, every once in a while the leader ring once his bell
if the follower feels ok with the leader's distance/pace, he rings back once. Else, he rings back twice. The follower can also ring twice whenever he feels he should get closer.

The benefit we got:

no need for the leader to turn his head and look back
the follower feels actually in control and not left alone


Carbon foot print from the manufacture of bikes?

We can do some rough estimates.  Let's assume that bikes are made exclusively of metal, and that only the mass of the bike counts (no energy consumed in welding etc.). Looking up the carbon footprints of aluminium and steel we have:

Material    Tonnes CO2 per tonne material   Source
Steel (tube)    0.857                       http://www.newsteelconstruction.com/wp/the-carbon-footprint-of-steel/
Al (best)       3                           https://www.carbontrust.com/media/38366/ctc790-international-carbon-flows_-aluminium.pdf
Al (worst)     20

So a bike weighing 10 kg would lead to somewhere between 8.6 (steel) and 200 (aluminium, refined using coal power) kg of CO2 emitted.

I couldn't quickly find reliable figures for carbon fibre or rubber, but metals are very likely to dominate based on the share of the mass in a bike, and the market share of bike frames.

Compared to an efficient car with 100 g/km of CO2 emissions, you'd have to replace 860 to 2000 km of driving with cycling for the emissions of making the bike to offset the emissions of using the car. This is a small enough distance that we can neglect other consumables.  While not a direct comparison it's a helpful one -- many people have a car and are being encouraged to get a bike and use it.  Food makes things interesting. Strava claims I burn 26 Cal/km on a hilly ride.  If I got that from eating beef alone (as a worst case), that would be something like 10 g of beef per km, or apparently 270 g CO2e per km. Of course we all know carbs are much better for powering our rides; typical sources are 10× better than beef.

Returning briefly to the original claim, when I've seen this claimed it tends to use low mileage figures, and neglect the fact that the metals in cars tend to be recycled (for Al this makes a big difference).  It would make a good question at skeptics.se if you could source the claim more thoroughly.


Would Tri-Bars be advantageous for a 260 mile 2 day event

I would suggest attaching the bars and doing some test rides.

Is your bike, with it's aggressive geometry, stable when using them?
Are you comfortable using them?
Does this new position provide some relief, or is it just more annoying?

I think you're the only one who can determine if they'll be an advantage to you. In general, I'd think the extra position would be an advantage.

Even with 4 positions on your standard drop bars, being able to take weight off your hands and put it on your elbows might be a welcome relief, even if it's just for a short period of time.


Some bike shops will disassemble and pack a bike for shipping. For a fee, of course.