What is the difference between different types of disc brake pads

Youll run into two types of metallic pads- sintered metallic and semi-metallic. The term "metallic" without any modifier gets used for a couple of reasons- a) many manufacturers don't offer both varieties of metallic pads for a given brake, so the type is implicit, and b) lots of folks don't know the difference or think the terms are interchangeable. They are similar, but different:

Sintered metallic pads offer the best stopping power, but also cause the most rotor wear and can make the most noise, especially when wet. They are also the least affected by adverse conditions. Sintered metallic are typically used in downhill/freeride applications, but can be used for less demanding riding types as well. Depending on the setup, sintered pads can feel "grabby", that is, that they lack modulation at the lever. That problem tends to arise on more powerful brakes with larger rotors though, and both of those factors play towards that perception.

Semi-metallics are a tradeoff between braking performance and pad wear/noise. They still stop very well but can be a little less noisy and cause a little less rotor wear. They may also offer better lever modulation than sintered metallic pads. This pad type can often be found on higher end all-mountain, trail, and cross country oriented brakes, though some manufacturers opt for sintered pads while others may opt for organics.

Organic pads are the kindest to your rotors and typically quitest, but don't offer the same bite as metallic pads. These pads also wear the quickest. This does not mean that they're low end pads though, and depending on conditions, riding style and personal preference they may be a great choice. Organic pads can offer the best lever modulation of the three pad types, but may not stop riders sufficiently in demanding circumstances.


Will any Shimano mountain bike shift cable set work with any Shimano mountain bike derailleurs and shifters?

Yes it will. The important factor for compatibility is the head of the cable that sits inside which will be the same. The cables will be significantly longer than you will need, so you'll have to cut them down to size. Use the old cable housing to determine the length of housing that you need (provided that it's been working well at the current length). Then thread the inner cable through to the derailleur and adjust your cable tension, then cut off the excess cable.


Which is faster, going all out then burning out, or steady pace all along?

I don't have the time to give a full answer at the moment, but I'll upvote a full answer and delete mine. The short incomplete answer is that you're better off pacing yourself relatively evenly. The reasons are both physics and physiological. The physics answer is that drag increases nonlinearly with speed so at higher speeds you're using more of your energy overcoming drag. The physiological reason is that when you go over threshold, you get tired (that's why it's called a threshold) and the time needed for recovery is exceeded by the time you're able to spend above threshold, so the net effect is that your average power output will be lower.

These two effects, the physics effect and the physiological effect, mean that unless your ride is shorter than, say, a minute, you're better off pacing (nearly) evenly.


Is SRAM Apex crankset compatible with 6 speed chain and rear cassette

Probably not as the Apex crank is designed for 10 speeds, a 6 speed chain will be too wide to fit onto the smaller chainring without jamming on the larger chainring. You would be OK using a 9 speed chain as they are pretty similar to 10 speed chaing in width. So sorry, you will need to up the number of speed front and back at the same time.


Looks like the barrel adjuster has been broken off and has floated down the shift cable, so the shifter end of the cable housing is not anchored.

The shifter unit should look like this

You might be able to glue the inner barrel back on to the shifter body. The housing is pulled back into the shifter so the glued joint would be compressed rather than pulled apart.


Is it really safer to ride in the road than on the sidewalk?

In most scenarios, it is not safer for you to ride on the sidewalk. This has been demonstrated numerous times in numerous studies. I won't attempt to site individual studies here, but I will sum up the reasons.

One is that you create more potential points of impact. When you exit the sidewalk to go through an intersection, driveway, or parking lot entrance/exit you are in danger from the cross traffic as well as parallel traffic making turns. The latter danger is greatly reduced if you ride in the street simply because you are in the same lane as those drivers.

Furthermore, drivers simply aren't watching for cyclists on the sidewalk. Cyclists typically move much more quickly than pedestrians and drivers aren't prepared for that. Cyclists seem to "come out of nowhere" as compared to slow moving pedestrians. Pedestrians are also able to stop much more quickly if a driver doesn't see them.

All that said, there are some situations where cycling on the sidewalk is safer. Personally, if the speed limit is under 40 mph, I typically ride in the street. If it's over 50 mph, I typically ride on the sidewalk. If it's between 40 and 50 mph, I judge the road based on how many entrances and exits there are, how wide the shoulder is, how much traffic there is, etc.

Mike Baranczak said it beautifully in his comment, "Riding on the sidewalk is always a bad idea. But sometimes riding on the road is a worse idea. You have to decide based on individual circumstances."


Itinerary suggestions for a weeklong trip along New York and Vermont Borders

It's not central Vermont but I can vouch for the routes in this PDF in the Northeast Kingdom. I did a modified version of the "Around the Block" ride and threw in some of the many gravel roads in the region (and across Vermont) that make for superb touring routes.


Which side should I pass other cyclists on a UK cycle path?

Of course you keep left, overtake on the right and queue like a good British person at junctions!

However, there are no rules. In 2006 British Waterways, concerned at the popularity and over-crowding problems on tow-paths did a consultation to work out if they needed a 'keep left' policy. It was deemed that such a move would be unpopular and not adhered to (and certainly not policed). Therefore, if there is no keep left idea then overtaking on the right cannot be deemed to be against any code.

Most cyclists over the age of five seem to appreciate the 'keep left/overtake on the right' idea, however there are some scenarios where this goes out the window in deference to safety. Going over Kingston Upon Thames Bridge the cycle lane is two-way, but you would be a brave cyclist to stick to 'keep left' when joining the bridge to go south - cyclists heading north are wanting to join the main highway and are crossing past your path. Going on the right is the expected norm at that particular point and, with it, overtaking on the left...


You will need to maintain:

tyres, chain, brakes; less frequently, chain ring, freewheel (or sprocket); even less frequently, bottom bracket

Their beauty is their simplicity.

By all means get the kit to true your wheel, but that again is something that I'd lump in the "even less frequently" category.


The Australian police have some Hawk bikes, and there is an Australian company "Hawk Racing" I mention this as there appears to be two Boomerangs on the badge. Should that read "Hawk CCM"  "Hawk ? Cycle Manufacture"
Of course this could be a resellers badge and manufactured elsewhere.

ref police

ref company


In the comments the point is made that there are several bike brands with bikes similar to this.

As an example (not an endorsement) here is one sold by Olmo


Can't identify this bolt. Please help. Bolt from adjustable stem

Looks like any standard M5 or M6 bolt. Go to a hardware store, find a nut that will screw on, and find a new bolt with that nut.


Oil or grease leaking, I think, from hub

Definitely not normal. I'd take it back to the dealer where you bought it. If you bought it online, I'd contact the reseller and let them know you're taking it to a local bike shop to get fixed - and that you'd like to be reimbursed.


How can I tell which road bike components/groupsets are better?

Typically the majority of their yearly R&D is spent on their top of the line group, then they will trickle down it's technology to the next lower group, and continue that way, so usually, this years tiagra is close to last years 105, etc.   The major thing to look for is # of speeds in a group, weight, and finish.

I believe the 2010 Sora(3400) set is a 9 speed, where the 2009 tiagra is a 9 speed - the major difference is the thumb button of Sora(3400) versus the finger paddle of Tiagra(4500), a substantial difference.

the quality goes 2200 < Sora < Tiagra < 105 < ultegra < dura Ace


Alternating two forks on a single bicycle — do I need two headsets?

Its a lot of faffing about to swap forks.  They're not really intended for frequent changing.

Best practice in this case would be to obey Rule 12  and to own a second bike set up the way you want it.

Your other option is to buy a light-weight suspension fork, and to make sure it has a lockout.  That gains you the ability to have a rigid, but doesn't give you the weight saving.


Do 7-speeder and 21-speeder have similar minimum range of gear-inches?

The simple answer is no (to the 21 speed vs. 7 speed question having similar minimum range).  The better answer is yes if the single front chainring matches the # of teeth of the smallest chainring on the 21 speed.

Remember that with a 20" diameter tire, even a 1:1 ratio (20 gear inches) is a decent hill climbing gear.  For example, on my 21 speed bike, I have 26" diameter tires and a 24/28 lowest gear so that is about 22.3 gear inches so if you had say a 34/34 setup (with 20" tires), your gear would be even lower than mine.  To beat 1:1 on a 20" tire I would need 24/32 gearing on my bike which is possible but would cost me some money to get.  I would say shoot for 20 gear inches and go from there.

Whoever recommended borrowing someone else's bike and testing that first seems like good advice.  That will give you a baseline to tweak your gearing from.

What you may want to try is gear the bike so you can normally make the hill in the 2nd to lowest gear, thus giving you 1 more bailout gear for when you are extra tired.  Condition yourself to be able to make it up in 2nd gear but you will have the assurance of having 1 lower gear.  For example, instead of a 34/34 setup being your lowest gear, you can make it so you have 28/28 as your next to lowest gear, then you will have 28/34 as your bailout gear, which with 20" tires, would give you about 16.5 gear inches.

Finally, yes I think if  you don't go ultra low on the lowest gear, then a wide range 6 speed should also suffice for normal "flat" riding and coasting downhills.  For example, 28 teeth in the front and 11,14,18,23,28,34 in the rear would give you a gear inch range of 16.5 low to about 51 high.  Just F.Y.I. (and for reference), my favorite and most used gear on my 21 speed is 34/20 which with my 26" tires gives me 44 gear inches so even if your smallest cog is 13 (not 11), you will be at 43 gear inches in top gear, good for a leisurely 9 to 10 MPH (14.5 to 16 kph) pace comfortably.

Good luck!


Are there any scientific studies proving the benefits of clipless pedal systems?

The Pedaling Technique of Elite Endurance Cyclists: Changes With Increasing Workload at Constant Cadence was published in the International Journal of Sport Biometrics 7:29-53, 1991. However, it seems to come to the conclusion that they don't really make any difference as far as pedaling efficiency goes.
"...while torque during the upstroke did reduce the total positive work required during the downstroke, it did not contribute significantly to the external work done because 98.6% and 96.3% of the total work done at the low and high workloads, respectively, was done during the downstroke."
This is echoed in Physiological and biochemical determinants of elite
endurance cycling performance published in the Medicine and Science in Sports and Exercise 23:93-107, 1991. There are numerous graphs showing that pedal force is only exerted between the top and bottom of the downstroke, represented by a very sharp parabola spiking at 90 degrees from vertical.
That said, I think it's obvious to anyone who has ever done any particularly technical riding with and without clipless pedals that clipless pedals significantly improve the handling of a bicycle. A fact which is probably more difficult to verify through scientific studies.


How safe is to use 700x25-32C tube on a 32C tire?

It is completely safe and shouldn't be of concern.  The only existing questions I can find discuss using an undersized tube (18-23 in a 28 tire, 23-25 in a 32 tire) and even those cases might work.  (If you've ever pumped up a tube to find a puncture, you've seen that tubes typically can easily expand far more than their rated size.)

The tube doesn't contain the pressure; the tire does that, so max pressure is purely a function of what the tire is rated for.


Is it worth buying used bikes of old models?

In bicycles, the technological advance is not as fast as you might think. This is due to the UCI, which blocks a lot of new technologies or is slow to allow them in races. So I think as long as the older bike is in good shape, there won't be much difference. Maybe it's a nine-speed instead of the modern ten or eleven, but that doesn't really make a difference, especially not if you're not going to ride pro.

That said, be careful about carbon frames and parts. They might be damaged from falling over, crashing or similar, without the damage being obvious. Look for (deep) scratches in the paint job, hairline cracks (especially around joints), discoloration or deformation.


Prostate-friendly Saddle and Sitting Angle

My scrotum (pardon my french) prefers this style of saddle:

I also tried this, but didn't like it. It seems good on paper, but my butt always wants to slide forward, plus not being able to squeeze the saddle between my thighs when going over obstacles means less control over the bike.

Anyway, your best bet may be a recumbent bike. I have one, the big drawback is that it climbs hills like a brick, but comfort is perfect.


Are bike repair shops averse to changing chainsets?

The chainrings last a long time but are expensive, and a lot of cyclists are surprisingly tight when it comes to servicing.
Worn rings should be replaced when necessary though, otherwise the shop is throwing away good reputation and good income.
The teeth on many modern rings are often quite pointy and shaped, making identifying wear that much less straightforward.
I'm sure there's no one true answer.


my first frame jig - a customized one - which addons and features to add?

You should use tapered cones, so they work with any BB. There's no need to have different fittings for different BB.


Why are electric bikes ranked on torque ratings?

Addressing just the actual question as stated to avoid a 3,000 word essay:

With this in mind, how to interpret the advertised torque for a bike with a mid-drive hub, since it's heavily dependant on the transmission?

The advertised torque on a mid-drive bike will tell you over how large a band of cadences and how steep a hill the bike can actually provide the advertised assist level in watts.  (generally 250W equivalent mechanical rider input at the crank.)
A low torque bosch active line motor might only provide 250W of equivalent mechanical input assistance at exactly 70rpm on flat ground, whereas a Performance CX can provide that assist level at much lower cadences and on much steeper inclines.  The manufacturers try to reduce this to a simple number because it's consumer marketing.  (and also the drive system manufacturers don't sell you a final assembled bike, so they don't know what final numbers will be at the drive wheel in the installed system.)
The marketing is targeted to consumers buying finished bicycles made out of mass market bicycle parts.  In reality the transmission is always going to go from a bit over 1:1 to around 36:11 to 38:11 and the drive wheel will always be about 26" to 29" outer diameter, these things aren't just infinitely variable to get whatever outcome you want.
Certainly if it were all made out of infinitely ideal "high school physics" components you could use any combination of motors and gearings to get any torque number you like, but these things have to be made out of real materials that don't strip teeth or snap in half or overheat when spinning at the speeds that people's legs actually turn, so there are a lot of engineering compromises to be made.


Can I use Shimano Ultegra 6800 BBR60 Bottom Bracket on 105 groupset

Any hollowtech II bottom bracket should be compatible with your crankset. For the frame, you will need to make sure you get the proper thread. Most frames will be BSA thread. Older Italian frames will be Italian thread. If your frame is Italian thread, both bearing cups will thread on clockwise. If it is not, the drive side will thread on counter clockwise. Pay attention to the spacer arrangement on your frame and install the bottom bracket with the same arrangement. Should just be a pretty simple swap.


The Marathon Racer is also available in 18". Won't be as puncture resistant as the Plus, but lighter.

(My (second hand) Birdy is still on the Mad Mike's it came with. My previous folders (20" tyres) used Big Apples, and I didn't have puncture problems, and the Apple is also available in 18", but it's fatter.)


How do I repair a broken chain on my old BMX bike?

That chain should work OK. 300 links means probably a halflinks chain. Most BMX bikes are 1 speed and many use half link chains.

You will need a chain breaker though to get the length right.
To get the length right, count the old links - DO NOT measure the actual length of the old one as the chain could be worn (stretched).


How do you measure the length of a loose spoke?

Generally speaking, the unstretched length of a spoke should be measured from the inside of the J bend right down to the far end of the spoke.

Your best tool for doing this is either a metal ruler where the 0 measurement is right at the end of the steel, or a normal ruler with a notch filed in the end, down to the 0 line.

The best method is to hook the J of the spoke over the end of the ruler, and then read off where the other end falls.  Accuracy to the millimetre is fine, no need to go any more precise.

Here's the Park SBC-1 which does exactly the same thing.

Since spokes are sold in metric lengths, you'll always use the metric side.  See how the J is hooked into the hole at 0?  This one is about 268 mm long.

Another method is to simply bunch the spokes in a fist and push the threadded end against a flat surface.  The longer spokes will poke up more.

Things of which to be careful:

the amount of thread rolled onto the spoke could be different between types
the thickness / gauge of the spoke could be different, giving it different flex characteristics which could move load to this spoke, or away from this spoke
Gauge of nipples should match gauge of spoke too, else they could back themselves out over time, or make tensioning harder.
Finish - spokes may be galvanized, chromed, blacked, or coloured.  Some riders care about this kind of thing.
Set - a used spoke will subtly vary the J bend at the hub.  This can stress the used spoke and make it snap easier.  It can also sit differently in the hole, and may adjust over time causing the wheel to untrue erratically.
Nipples - have a defined tolerance for damage.   If anyone has monstered the nipple with the wrong size of spanner then it may be hard or impossible to tension the wheel right.  If possible reuse the nipple from the broken spoke, assuming its serviceable.

Personally, I have no problem reusing an undamaged salvaged spoke.  I've also rebuild a whole wheel onto a new hub reusing all the spokes in that wheel.   However none of these were high performance wheels being pushed hard.

Use your best judgement of course.


Braking surfaces (pads, rims, rotors) must never be lubricated in any way. Doing so can severely affect braking performance and is dangerous.

You can clean the rotor with isopropyl alcohol or mineral spirits.

The pads will probably have to be replaced as oil permeates into the pad material. You might be able to save them by cleaning with alcohol and sanding off the top layer, but replacement is the safest option.


Here's the sole Colnago road tandem picture I could find anywhere.

Is your bike anything like this ?

From http://www.ebay.com/itm/Colnago-Tandem-Bike-X-Campagnolo-Groupset-Pantographed-Vintage-Very-Rare-/151292492125?hash=item2339bc395d&pt=LH_DefaultDomain_0&nma=true&si=3DCdggTFjbiHTJYmI3jOxvB%252FJrE%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
and there are more photos there.

If so - it has single pivot caliper brakes, and definitely steel rims.

Your first bet would be to swap out the brake pads.  Then change all the brake cables, both inners and outers.  These are both maintenance tasks and do not detract from the bike.

Replacing the single pivot with dual pivots would help, but finding something period might be difficult.  IMO safety is more important than originality, but others disagree.

Finally, steel rims tend to be poor at braking anytime.  If you can find some 700c alloy rims, they will brake much better.  Downside is they're fractionally smaller than 27" wheels, so you'll need new tyres and tubes, and the brake calipers will need to reach further, which can compromise their effectiveness.


How can I prevent cars from passing me too closely?

Use proper positioning. This is most important. Unless the outermost lane is as wide as two SUVs, ride in its center. When it's safe, reasonable and necessary to let drivers pass, kindly move over; but always leave at least 18 inches (0.5 m) between you and the curb. The driver behind you may have to wait a minute or two, but they'll survive. If they've waited a few minutes, be nice and pull over. (Adapted mainly from Wikipedia citing Cyclecraft.) Paradoxically, correct positioning will stop most drivers from buzzing you. Correct positioning can be scary, but does get easier.

There's more to vehicular cycling. You must read more about lane release. Also read "Street Smarts" online: either the American edition or left-hand-drive edition. If you want, you can also read Cyclecraft, or take a class, or watch some videos. (Can anyone recommend some videos?)

On rare occasions, drivers may still buzz you. To prevent this:

Use a safety flag. A spring-mounted one: e.g. a Flash Flag. (Source.) It must be spring-mounted, so that it can bend easily if hit. (If you can't afford a flag: Maybe you could use a dollar-store pool noodle plus a washable marker pen. See here.)
Or use a doll. Put a baby-sized doll in a trailer or rear-mounted carrier.

About attempted murder: If a driver ever intentionally endangers your life, note down the license plate number, location, time, and date. If you value your safety, don't touch the driver's car. Contact a cop: preferably immediately; but better later than never.

This post is marked as community wiki. Please add to it.


A coaster brake is really your only option for foot-operated braking, and most complete bikes sold with coaster brakes have the coaster as the only brake. My experience is that mixing hand and coaster brakes takes some getting used to, and most people don't want to bother.

This limits the selection of coaster brake bikes to mostly cruiser and city bikes. Most of those are single-speeds or 3-speeds. Both Shimano and SRAM offer 8-speed internally-geared hubs with coaster brakes, but I don't know whether any current production bikes come with 8-speed coaster brake hubs from the factory.

If you wanted to have a more versatile bike with a wide range of gears and a braking setup that includes a front brake, one way would be to have a rear wheel built using one of the 8-speed hubs. The considerations for that include:

The frame would have to be able to accommodate an internal or single-speed rear hub. This means it would have to have either horizontal/track type dropouts or an eccentric bottom bracket.
Most internally geared hubs are limited to one chain wheel in front and one cog in back, so you're limited to the number of speeds inside the hub itself.
Both the Shimano and SRAM hubs come only in 36-hole drilling, not the more popular 32-hole. This would somewhat limit your rim choices.
The derailleurs, chain wheels and cogs from the derailleur drivetrain would become surplus, along with the rear brake and its lever.

If you wanted to start with a bike that's really close, the Breezer Uptown 8 or Downtown 8 come with 8-speed hub gears and hand brakes for both wheels. You could purchase the coaster hub and have a bike shop rebuild the wheel, keeping the rim, shifters, cog and chain wheel. I wish I could say that you could just buy a kit to convert from one type of brake to the other, but to my knowledge, the hubs have different internals. Current cost would be a $600-800 bike, $200+ hub, plus labor. You could probably sell the old hub and get a little bit back.

Another option might be to get a cruiser with an 8-speed hub and add a disk brake, but this would require replacing the fork and front wheel. Probably more cost-effective but more of a challenge to find a compatible fork. Too many variables to estimate what that might cost.

Good luck in your search.


How can I tell if the size of a bike is right for me?

Frame fit

Primarily, a bike fits if you can position pedals, saddle and handlebars relative to each other so that they match your body's proportions. Secondarily, when these contact have been set, other frame parameters should fall into place so that the riding characteristics are as desired. That includes e.g. toe clip overlap, stand over height, bottom bracket height, heel/panniers clearance, steering geometry, or that an extremely short or long stem gives a weird steering balance. Depending on what you use the bike for, the importance of these parameters varies.

Does "frame size" equal "seat tube length"?

If you consider frame fit as putting the contact points in the right spots, the length and angle of the seat tube is one of the less important dimensions. By choosing the right seat post length and setback, it is possible to put the saddle in the right position relative to the pedals (or, simplified, the bottom bracket). Generally, on most frames, most riders can put the saddle in the right position relative to the bottom bracket.

Depending on the use of the bike stand over height (or clearance) is more (MTB) or less (road) important. If you want a certain stand over clearance, of course this limits the frame size to a certain amount. This is easy to determine: With the correct tires and wheels, the height of the top tube should be lower than the length of your inseam.

How to determine "frame size" instead

The critical point is often if you can put your handlebars of choice in the right spot, too. One thing to consider here is that drop handlebars have a significantly longer reach than straight ones. This is because the normal hand position is on or behind the brake lever hoods with a drop bar, and not on the straight section next to the stem eye. If one does not want to resort to extremely short or long stems, a frame usually only allows for a good fit with either drop or straight bars.

Working backwards from the hand position through handlebars and a normal sized stem (ca. 8-12cm on a classic frame like this), one ends up at a certain position where the top of the head tube should be.

Stack and reach

The corresponding frame dimensions are the vertical and horizontal distances of the head tube upper end from the bottom bracket, called stack and reach. Unfortunately especially frame reach is quite difficult to measure on a frame without complicated measurement setups (or a good picture exactly from the side without perspective distortions). Therefore many tend to use top tube length as an alternative to reach, and ("virtual") seat tube length instead of stack. One should be careful though: The position of the top of the head tube not only depends on seat tube and top tube lengths, but also on the seat tube angle (which can be even harder to measure than reach).

The easiest way to find out your needs regarding stack and reach is to measure a bike which fits you well and has the relevant handlebars setup. One way to do this is to take a photo exactly from the side and from quite far away, and measure in the picture.

What does this mean for you?

As you say, stand over clearance does not bother you with this frame, so the seat tube length is very likely ok. On the picture there is also plenty of room to move the saddle forwards, in the worst case with a zero setback seat post. So the saddle probably position fits you. Good.

I am more concerned about whether the frame reach is too long, when changing to a drop bar. But as far as I know, the classic Raleigh road geometries do not have overly long reach, and the stem shown on your picture is way longer than what I would consider aesthetically pleasing on a frame like this (especially with quite little seat post to be seen).

Without knowing more about the frame and your fit preferences it is very hard to advise if it will fit you in this regard. The fact that the frame was built with a classic quill stem in mind, but has a threadless fork today, does not make it easier: It may be that you can't rise the bars enough with an ahead stem (and the fork already being cut).

The easiest thing would be to just try putting a drop bar on the frame (ideally with an adjustable stem temporarily). With a fixed gear that should be easy to do. Ride and adjust, and you will feel if it fits.

What else?

Apart from all that I think that the average 56cm frame is quite a bit too small for the average 1.88m male (horizontal top tube, or "virtual seat tube length" assumed). I am 1.83m myself and usually start looking around what is labelled as 58cm.

I'm pretty sure that the fork is not original. Ask the seller if the original still exists. It probably is a threaded fork, which allows for higher building quill stems. And it probably looks nicer, too.

Finally: I have never heard about problems with the thighs rubbing on the seat stays before...


What pressure should I run my Mountain Bike tires at?

Tire pressure is generally a trade-off between three things:

Rolling resistance (more pressure == rolls easier)
Pinch flat resistance (more pressure == less chance for the tube to tear when a rock squashes the tire toward the rim)
Grip (with less pressure, the tire can conform better to rocks, roots, and other terrain giving a larger contact surface)

If you are riding terrain where grip isn't too much of an issue (flat or low-angle dirt and dry rocks for example), then higher pressure will keep you going fast without pinch flatting.

If you are riding steep downhills and/or on slippery open rock outcroppings, grip will be more important than rolling resistance, so use as little pressure as won't pinch-flat quickly.

There is a 4th trade-off as well: weight. You can buy double-sidewall downhill tires that allow you to run very low pressures (such as 25psi) without any danger of pinch-flatting, but these can weigh almost double what normal cross-country tires do.

As mentioned in other answers, your tires don't have to be the same pressure. Usually grip is more important on the front tire since most of your weight is on it while descending difficult downhill sections. Similarly, when riding on flat or climbing, most of your weight is over the back tire, so rolling resistance and pinch-flat resistance are more important for the back.

I personally ride with a low-pressure (30psi in a tire rated 35-65psi) double-sidewall downhill tire on the front and with a higher pressure (50psi in a tire rated 45-65psi) cross-country tire on the rear. I sacrifice some weight, but otherwise get the best of both worlds: fabulous grip going down and easy rolling on the flats and climbs.

Use your best judgment in going below the rated pressure of the tire, as pinch flats become more likely. If you go below the rated pressure, be sure to test it out on hard impacts (such as a rock-corner) on easy terrain before throwing yourself at high speed down a mountain where a blow-out would be catastrophic.


JIS, short for Japanese Industry Standard, is by the far more common and is the one used by all Japanese manufacturers including Shimano. As far as I know, the only manufacturers that still produce ISO cranks are Specialites TA and Campagnolo, and the latter only for track bikes.

Triple crank chainline is measured at the middle chainwheel, so you can use the number as it is.


Hire road bike for one day for race (never ridden one before)?

In your first tri , you’ll have all sorts of new things to concentrate on, I don’t think an unusual bike should be one of them.

When I’ve seen people ride road bikes for the first time, it’s the gear shifting that’s often trickier and more distracting than anything else. I’ve seen people take more than one ride to get the muscle memory to change gear in the direction they intended. It becomes intuitive, but through practise.

For your first tri you’re also only racing against yourself. So if you know how fast you normally ride in training, you can compare how fast you race, and know if you’ve done a good job on race day.

If, afterwards, you want to do a second triathlon, put the rental fee you save towards a road bike to train and race on.


Is 7-speed for 10-speed cassette replacement possible?

Higher number of speed cassettes and freewheel are not wider, they have smaller sprocket spacing.

If you were talking about a cassette/freehub system, you would be able to fit a 10 speed cassette on the existing hub because the freehub body is the same width for 7 to 10 speed cassettes. (11 speed requires a wider freehub body on road bikes).

I'm not terribly familiar with freewheels, but I would think the same principle holds.

However, if you have a 7 speed rear, freewheel equipped, Tourney level bike, and you want a 10 speed rear, you really want a whole different bike. To get a 10 speed rear you need to upgrade to Tiagra or Deore, depending on if you have a road or mountain style bike. You'll need to replace the crankset as well as the derailleurs and shifters. Buying the bare drivetrain groupset will be expensive, require a lot of time to install, require special tools and will give you a lot of headaches trying to get it set up correctly.

Go the easy route and get an upgraded bike. It will probably be cheaper and you'll get an upgrade on every component, not just the drivetrain and it will work right out of the box.


Can I expend same or less effort riding a mountain bike than road bike?

Whelp, how to answer this? Depends what you mean by 'less effort' I guess.

I'll give the short answer up front. Road bikes are more efficient (therefore less effort to ride) than mountain bikes on road surfaces. We know this because road bikes have been optimized for speed and efficiency for a couple of hundred years. Geometry mess, riding position, wheel size, tire width and gear ratios all contribute to this.

To address points 2 and 3 about gearing. Everybody has pedaling cadence and gear ratio that is most efficient for them. A casual rider would use a lower gear ratio, a pro racer will use a much higher one. The availability of lower ratios does not make a bike more efficient (as long as they are low enough for the rider), Road bikes have enough gears to allow selection of an efficient ratio and their lowest ratios are sufficient to allow easy acceleration from a stop. Mountain bikes have lower ratios than road bikes to allow riding up steep inclines (and to pull their greater mass around).

Is there a way to test this? Yes. The advent of (relatively) affordable and accurate power meters make analysis of rider performance available to even casual riders.


There are some solutions in forms of bottom brackets designed to run 30 mm cranks in a threaded BSA bottom bracket shell. The deciding factor is the spindle length.
Searching the net for "bb30 crankset in bsa frame" gives e.g. this:

Threaded to 30mm Angular Contact BB - Black
Our solution for running a 30mm spindle crankset in a BSA threaded frame.
Notes:
For use with 30mm diameter cranks with a spindle length of at least 104mm. Will not work with standard BB30 cranksets.


Clipless vs. Flat Pedal Speed Difference

With flat pedals, the only thing holding your foot to the pedal is friction. Friction only exists if your foot is in contact with the pedal -- what physicists call "normal force" or "contact force". No force, no friction, and your foot is off the pedal, by definition.
Because of this fact, you have to exert some amount of pressure to the pedals all the time, particularly on the back-stroke...unless you have super Jedi warrior reflexes and can move your foot in exactly the same arc as the crank, your foot is either going to come off the pedal, or it's going to have to be pressed against the pedal at least a little bit to maintain traction. This "little bit of retarding force" directly counter-acts the main driving force of the other crank...you are literally working against yourself; your legs are working against each other...and this extra effort that must be expended to maintain traction also won't show up in a power meter, depending on the design of the power meter.
It's a physical fact that flat pedals require you to keep your foot pressed against the pedal, and this backward force generally is non-productive and actually detracts from forward force. The main argument is how significant of an effect this is. There have been studies to measure the difference, but not all of them directly measure the right things. The current consensus is that the effect is small, and efficiency for most practical purposes is not greatly different between flat pedals and clipless/clipped pedals. To directly answer your question, I believe attempts to find a difference through practical testing (the straight road, direct comparison test) have failed to find a reproducable difference.
It may be a difference too small to matter, but other things considered, clipless should be more efficient because the need to apply this retarding force to the cranks is removed.


Is it correct that with fixie you shouldn't keep the chain too tight because it can ruin the drivetrain?

That is mostly correct. Given that the circularity of the chainring, bearings and rear sprocket are never ideal, there will be a position through a full crank's rotation when the chain is the most tight, and a position where it is the most loose. It is recommended to find the tightest spot and tune the chain tension to be just right in it. Then, just in case, you can find the loosest spot and make sure the chain won't hop off the teeth if shaken in the second position.

Overtightening a chain would not give performance benefits while simultaneously it would start pressing both chain and chainring excessively, not benefiting their wear life.

  Is it normal that I have to tighten the chain probably at least once a month because it gets too loose with casual riding, no more than a 100 miles per week?

If it is not the rear wheel axle sliding forward because of a low torque on its axles or because of bad nut design/quality, then it is the chain. You would have noticed the axle sliding because the rear wheel would become misaligned in the rear dropouts and the tire would start rubbing one of the rear chainstays.

It is possible that a chain of poor quality would wear faster than desired, effectively "stretching" itself and thus becoming loose on the drivetrain's teeth over time. I've read reports that so called half-link chains used in BMX are quite prone to it. Try using a better, possibly more expensive chain.

Again, if the chain seems "loose" to your taste but you cannot throw it off the drivetrain's teeth by hand, it is unlikely it will come off during riding. In that case, let it be for a while.

And again, do not forget about regular maintenance of the chain, that is, replacing it after it has worn and become longer by 0.75% of its original length.


Here's the Shimano datasheet. So we know it's a square taper, ISO-threaded BB. So a UN54/UN55 is the replacement part (take the UN55).

73 is the shell size: 73mm.

113 is the spindle length: 113mm.


Yes that's normal for an 80s style bike.  Notice the rear of the dropout slot goes back the same distance, but the drive side has the derailleur hanger there.
You can fit a block in the non-drive side, but having the slot open allows adjustment both ways.  Getting the rear wheel aligned right can be easier if you clamp on the rear brake while doing up the axle nuts, and holding the wheel in the middle of the chainstays while doing the nut up with your third hand.


Which Shimano freehub body fits Campagnolo Calima?

The search process should be like this: First, search the web for "campagnolo calima spare parts". The first hit should be a product page that has link to spare part catalog. Download and open the catalog. Search for the page with Calima.
The answer is FH-BU015X1.


Why does my bike left gear shift have more than 3 combinations?

Sounds like a friction front gripshifter with a "Micro-Adjust" shifter.  As mentioned in the comments, that will let you "trim" the shifting a bit.  As you change gears in the rear gears, the chain moves a little side to side, and may rub the front derailleur.  That shifter lets you move the front derailleur cage a little bit to alleviate that chain rub.


Pedal on exercise bike fell off, not going back on

Which side pedal came off? This answer might help, pedals don't both screw in the same way.

If not, can you attach a photo? If you don't know the names we can help figure it out for you.


What is the reason for starting before the traffic light turns green?

The "early start" allows cyclists to clear the junction ahead of motorists, this is useful for cyclists making off-side turns (right in the UK, left in the US). It also helps cyclists going straight on avoid conflict with motorists making near-side turns (left in the UK, right in the US).

The UK and many places in Europe have Advanced Stop Lines (Highway Code rule 178) at traffic lights:

These allow cyclists to get ahead of motorists without jumping the red light.

For junctions without an Advanced Stop Line you'd have to weigh any benefits of clearing the junction against the potential legal consequences, the likelihood of increased driver hostility and the risk of colliding with a vehicle jumping the lights from another direction.

Personally, I don't jump red lights. On the roads I cycle on I think it would be more dangerous than waiting for them to change.


Tightening bottom bracket prevents crank spindle from turning

If everything is correct you should be able to tighten both sides to the specified torque without it having any impact on how hard it is to turn the cranks.

From what you describe, it may be that you are missing a spacer on the drive side.

With cartridge style bottom brackets (BB), there is usually a spacer that sits on the drive side between the BB and the frame:

The spacer is not required if you are using a specific type of front derailleur (E-type, they mount using a bracket that you put the bottom bracket through) or if your bottom bracket shell is 73mm.

But without the spacer on a 'standard' 68mm BB shell, the BB sits too far over when the drive side has been tightened and the non-drive side cup can end up pressing against the wrong part of the BB, causing the tightness.

Truvativ BB instructions with the full spacer/non-spacer compatibility chart and explanation about spacer usage and the BB shell size can be found here

If do you want to check the BB shell size, it's the measurement outside edge to outside edge across the width of the bike frames BB shell. If it's 68mm and you do not have a spacer then I would pay a visit to your local friendly bike shop as they will probably have spare spacers or can order you one in.


Will a change from 26x2.10 to 26x1.95 tires improve speed?

If you run your knobbies at typical MTB pressures, and you run your slicks at higher pressures, you should experience less rolling resistance, which could translate to higher speed.

I don't know what tires you're talking about exactly, so it's hard to say how much of a difference it will make. I run some pretty aggressive knobbies on my MTB (Panaracer Fire XC Pros) and with <35 PSI in them, that makes for some noticeable rolling resistance. On my vintage no-suspension MTB, I run slicks with 60-65 PSI in them, and those are halfway to being road-bike-like. Even with the MTB gearing, I can hold 15-16 mph on that bike for a decent amount of time.

You did not indicate what kind of suspension your MTB has. With any suspension, you're probably going to get a little pedal bob, which will rob you of some energy. That, combined with the upright riding position, will hold you back a little. But the engine (your strength) is more of a factor than tires, suspension, and bike weight.

Once upon a time a friend of mine-- road bike rider, likes Italian bikes, pretty fit at the time-- used to regularly get passed on a local muni trail by this little guy on a vintage mountain bike who was dressed in street clothes and riding to/from work. These roadies would be doing a paceline at a good speed, and the little guy on the mountain bike would just roll right past them, comfortably holding 2-3 mph faster. I wasn't there, so I can't tell you if the mountain bike guy had modified his bike or what. But he used to say "good morning" or something similar, every time he passed them, with a big smile.


Hydraulic disc brake clicks once when I pull the brake lever and the braking force is very bad

First, don't ride the bike if one of the brakes is not working properly. Not working well can change to not working at all and put you in a dangerous situation.
Take the bike back to the store where you bought it, a 2 month old bike with a major brake problem should be fixed under warranty. In any case if you do not have experience diagnosing and repairing hydraulic brakes you should have a professional address this problem.
The problem is likely that the rear brake has lost hydraulic fluid, or perhaps a seal has broken in the lever or caliper.


I've made several and documented at least some of them:

2 wheel trailer 1.6x1m: http://www.moz.geek.nz/mozbike/build/megatrailer

2 wheel trailer 0.8x0.4m: http://www.moz.geek.nz/mozbike/build/shoptrailer

12 more of the above with a better design

a four wheel, inertia braked trailer

2 wheel, single sided wheel mount trailer with telescoping drawbar

I much favour the mass produced design because it's easy to weld or braze together and quite robust. The chain-in-spring hitch is reliable and durable and very hard to break (the chain links eventually wear though but that takes years).


The most common reason why is your chain squeaking is because there is none or not enough lube on your bike. apply some lube on your chain one drop per rivet and wipe the access lube off (You can choose not to wipe the access lube but it will attract dirt & dust.). A chain with no lube will wear much faster than a chain that is lubed, and it will rust easily too.


There is plenty of discussions on the internet about larger volume tires actually being faster than narrower tires.  For example, a recent Cycling Tips pod cast has a good discussion. However, real world experience will likely be the opposite due to the tire construction used on the majority of tires available in the market place.

Tire construction

Unfortunately, tire construction is a confounding factor when discussing performance of large volume tires.  Most larger volume tires on the market use heavier casings and thicker tread, as they intended use case is "heavy duty".  Add in some puncture resistance strips (standard on most large volume tires currently in the market) and you get a very thick and stiff tire.

A stiff tire will have higher rolling resistance compared to a more supple tire  due to a a process called hysteresis, where the energy required to flex the tire slows you down and higher suspension losses (which has also been termed impedance).  Suspension losses vary by road surface and can be quite high on rougher surfaces. Here a stiffer tire response more slowly to road imperfection (i.e., flexes to accommodate the imperfection), which in turn vibrates the rider. The vibrating soft tissue "consumes" energy (actually it converts forward momentum into heat due to internal friction within the body). BQ showed this in an extreme context, where very rough surfaces more than doubled the amount of effort required.

All things being equal, a larger volume tire will also be heavier than a narrower tire.  Add in heavy duty construction found on most high volume tires, and you end up with a much heavier tire.  This results in a large weight penalty which can noticeably affect acceleration, furthering the feel of the tire being slower.

Because most high volume tires on the market have stiff heavy duty construction, these tires will typically have much higher rolling resistance than more narrow tires, which, on average, tend to be more performance focused, featuring more supple construction and lighter weights.

Light Supple High Volume Tires

An exception to this generalization is light supple high volume tires, which are currently quite hard to find.  These tires will also have low hysteresis and very low suspension losses as the supple construction means the flex easily and the large volume means you can run them at a lower pressure, there by greatly reducing suspension losses.  On most real world road surfaces (especially open chip seal or gravel roads), these type of tires will be faster, than a narrower tire of similar construction due to the large difference in suspension losses.

These typically will not have puncture protection, further adding to the suppleness. Lack of puncture protection is less of an issue in large volume supple tires, because the force placed on encountered objects by the tire is reduced due to the fact the tires flex easily and the tires are run at a lower pressure. This means the regular tire rubber is typically strong enough to resist the object and an extra puncture strip is not required.

Finally, a light suppler large volume tire will still be heavier than an narrower tire so there is an acceleration penalty. That said, this penalty is much smaller than with the "heavy duty" large volume tires and for most everyday riding it will be hard to notice.  It is therefore a bit of a non issue relative to the gains in comfort and higher sustained speed due to reduced suspension losses.

The real problem is getting your hands on light, supple, large volume tires.  Only a few brands currently exist, with pretty much all of them are being manufactured by Panaracer.


shimano xc30 mtb spd shoes for CycloCross?

If you throw some studs on those XC 30s ( don't skip that step ) you'll have plenty of grip and all around performance. Unless you travel into some higher price ranges where the really aggressive tread patterns usually live, you'll be hard pressed to find too much of a difference between MTB shoes and cross shoes.

If you end up in love with racing cross, you'll start to get a good handle on which equipment works best for you.


How can I tell if I have properly patched a tube? (specifically a 2" mt. bike tube)

I do like you do when riding, and I usually save up my tubes with holes and patch a bunch of them all at once. That way I can use a tub of water to both find the holes, and can go back through them after patching and test to see if they are holding air.

If I have any doubt after patching a tube, I give it a little time to cure and then I pump it up and hang it from a hook in my garage overnight to see if it loses air.


Campagnolo cabling: can I use other non-Campagnolo brands?

You don't have to buy Campy brand cables, but you do have to buy Campy-compatible cables, because they use a head that's a little bit smaller for both shift and brake cables. If you ignore this, it can seem like it's fine, but get stuck in your lever. The alternative in a pinch is taking a little off with a grinder or file.

Most shops will have individual carded Campy-compatible cables that are more expensive than bulk but not nearly as much as Campy. Some shops have them in bulk. There is no compatibility issue with using them in your Campy housings.


In my personal experience, anything you wear while riding that is even moderately water proof will trap heat and sweat and for me, I will end up just as wet if I had ridden with or without the jacket.

GoreTex and the like are just riding an edge of being helpful.  Short rides, cool temps, perfect.  Long rides, doesn't matter, you are going to get wet.  From the inside or the outside.  :)


Cannondale SAVE frame technology in entry price

All frames flex to some extent due to impacts or road shocks or vibrations. Some frames are better at absorbing this than others. All frame designers engineer their frames to attenuate these imperfections in riding conditions appropriately (for control/comfort reasons) by varying the size/shape of tubes and their compositions

SAVE is Cannondale's marketing term for this engineering. It isn't really honest to call it a "micro-suspension" anymore than any other rigid bike -- its just the frame engineer doing their job.

In a complete bike, you also have to take into account the rest of the bike beyond the frame like the saddle, handlebars, fork, tires, etc. in order to determine how comfortable/controllable the bike is. This is what you should assess the bike on, not some random marketing term.

You should go for a test ride before deciding on a bike. You may find that a bike without some marketing term like SAVE is more comfortable or better value to you than one with that. Or, you may like a bike with it. It would not be advisable to base the decision on buying a bike based on whether or not it was marked SAVE (or equivalent from other manufacturers).


Tubeless fatbike setup, does valve choice matter?

As far as I'm aware, at these pressures, there'll be no difference in performance.

A bigger issue might be the rim. The value hole will be either Shrader or Presta sized and will either not fit a Shrader or be hard work to seal with a Presta.


Don't buy a €3K first bike! Instead, split your budget and get one for <1K. There are plenty of good advice here already (my vote goes to randonneur-type bike), and each of the suggested types can be had for that price. Don't aim at the highest specs: you don't know yet what you'll need. Just get something decent in the middle. Indeed, get to your local bike shop and talk to them (it must be more than easy in the Netherlands).

Ride it for a year or two. If you do it regularly, then you'll know what you need, and then spend the better part of your budget on a good new bike. If at all.


Aluminum forks vs. carbon forks (with aluminum frames) what are the trade offs?

What is the make/model of the bike you are considering?  It may help in answering your question more pointedly.

There are all carbon forks (which are very expensive), and more commonly, carbon forks with carbon fork arms and an allow steerer tube.

I think you will find the carbon fork much, much better in terms of weight, performance and comfort compared to an alloy fork.  Most entry level road bikes ($700 and up) from the big brands come standard with a carbon fork.  Road touring is more or less the same.  I have an older Specialized Secteur which has relaxed touring geometry and some touring affordances.  It came with a carbon fork and I wouldn't want to ride it without one.

As far as durability, it all depends on the built quality, but I think you'd have to try pretty hard to actually crack a carbon fork while touring.  I've hit massive potholes and never damaged my fork.  I've blown out a lot of tires but the fork remains in tact.  They are very durable.  I'd be more worried about my alloy frame failing from fatigue than my carbon fork.

A touring consideration, If you want to mount racks or fenders, you need to make sure the carbon fork has eyelets or some hardware to do so.  It is not advised to use p-clamps on carbon forks.

So, if you can afford it, I wouldn't think twice.  Get the carbon fork.  It will steer and handle better, be lighter, and you can pick up the front end of the bike easier (like when hopping your front tire over obstacles to avoid impact).

For me, once I put some carbon on my bike, I usually and up wanting more carbon on my bike.  It just has really suitable characteristics as a bicycle material.


How to lubricate noisy joint on Dahon foldable bike?

For similar things on cars I use white lithium grease (e.g. this stuff on Amazon)—it is a good lubricant and sticks around the joint that you apply it to.

Any similar thick grease should work for this joint, but the crucial thing is getting it into the right place.  Taking the joint apart and applying grease to the mating surfaces is the best bet.


Installing a rear derailleur on a bike with a nexus 8 internal hub

This isn't going to be nice, because the frame doesn't have a  derailleur hanger built in, or routing for the derailleur (which you'd have to hack on with clamp cable stops or something).

On a normal frame, one would install either a derailleur with a built in claw (e.g. Shimano Tourney RD8153)

or an adapter claw (e.g. SunRace Rear Derailleur Adaptor Claw)

 .

(Pictures from Sheldon Brown's site)

But your bike doesn't have horizontal dropouts -- it has forkends. So, you could try a chain tug with a derailleur hanger on it:

This one is from Problem Solvers and is about 30 USD, but there are others from SunXCD, Origin8 among others. Then, bolt on a derailleur as usual.

Note that even if you get a derailleur on using the chain tug with derailleur hanger, you still need:

Wheel
Derailleur
Cassette/freewheel
Shifters
Cable routing


Assuming you already have a bike, have you looked into a trainer? Since you're not buying as much equipment, essentially just the resistance unit, you can get much better quality without spending as much.  I got a CycleOps Fluid2 and it's pretty quiet, and also folds down pretty small which would probably be beneficial in an apartment.  There's quite a wide range of them, and I understand that most of them are pretty quiet as long as you stay away from the cheaper "wind" trainers.


The main difference is that the tent gives almost no protection against thieves, where a shed gives a little more protection as it is.
And a shed can be improved a lot with a simple anchor ring which you fix to the ground or through a wall so it is very hard to remove, and to which you lock your bikes.
A well set up tent of a decent quality will keep the rain off your bikes as good as a cheap shed roof, but most tents are not made to do their work months at a time and many will let water through the fabric in heavy or consistent rain, while most sheds, even cheap ones, do a better job to keep the rain out.
Depending on the climate you have where you are, you may find damp inside both the tent and the shed, or more in one than the other, in which case I would expect the tent to be less protection, as most of those are meant for short term use.
A hard layer under or in your tent or even using a tent without build in ground sheet and adding a ground sheet on a hard underlayer will improve against raising damp and keeping water on the ground away from your bike.
But again, a shed will do better and it will be easier to build it up so ground water and rainwater collected on the ground will be kept out.
And a tent which is build good enough to compete with a shed will cost the same as a shed.
For short time storage, like the bikes of visiting friends who are only there for a week at a time, a tent makes sense. But so would any roof, even without the build up sides of a shed, and a well build bike should not get damaged getting rained on, as long as it can dry off properly after a rain shower. Within a tent the bikes may stay damp longer, depending on how the climate is where you are.


It's too long, and you should cut it again to get it closer to the right length.  As a guideline, you could look at pictures of similar bikes online and cut you own cable housing so that the curve ends up about the same.

If it's too short, the curve is too tight, and that adds friction.
If it's too long, it adds a bit of friction, and you can get things caught in it when you ride.


Do suspension seatposts work as well as a full suspension MTB?

Suspension seat posts and full suspension have different jobs and can't be compared.
The primary goal of a suspension seat post is to provide rider comfort.
The primary goal of bicycle suspension is to keep the wheels in contact with the ground to increase grip and control over rough terrain.  This has a secondary outcome of increasing comfort.


Where (UK) can we rent an adult tricycle or recumbent tricycle

Where abouts in the UK are you?  You might want to check out the following places:

London Recumbants - http://www.londonrecumbents.co.uk/bikes_we_hire.html
DTek - don't have a web site but can be emailed on dtekhpvs@btopenworld.com
FutureCycles - futurecycles.co.uk

Hope you get sorted.


Source an internal/hub derailleur for Bianchi Bergamo

You could order your own replacement hub, for example Universal currently lists the 36h Dual Drive (Disc) for $187.  These hubs are a relative rarity, and I don't doubt that your LBS price would be above $300.  Bianchi presumably got them in bulk for a bargain when they specified this frame.

If you're carrying heavy loads upgrading to 36h is certainly a reasonable solution and will definitely help.  You can also select a beefier rim - I personally like the Salsa Delgado, but rims such as the Velocity Dyad and Sun Rhyno Lite are perfectly fine as well. Lastly, get a professional wheel build.  All told you're probably looking at at least $320, most of which is dominated by the price of your hub.

Depending on your riding conditions and preferences, another solution might be to replace your Dual Drive hub with a normal 9-speed derailleur hub. This will cost a bit more than usual in the near term (you'll need to replace the shifter and the derailleur), but you'll have more wheels at your disposal.  Craigslist and eBay can be a treasure trove of relatively inexpensive handbuilt wheelsets, if you're patient.


Add front brake and/or improve back brake on 2012 Specialized P.24?

Get Odyssey cable & lever. It did magic to my BB5 5 years ago. This fork doesn't looks like it has brake mounts, so either get another fork or another (sick maybe) idea is to get actualy two bikes: MTB for offroad, 20 BMX for park and street. That's what I did eventualy.


First, take the chain off and shift the derailleur into position and see what happens. If it's still too far away, you can possibly eliminate the short chain (which does look too short) from the equation.

Without the chain, you should be able to see what is causing the derailleur to sit at that position.

You should be able to find what's preventing the jockey wheel from coming in closer contact with cassette ring by flexing and contracting all the movable parts on the derailleur.

Possibly, the derailleur hanger places it too far out?


Is it ok to extend/straighten legs fully while pedaling and will it give me maximum power?

I seem to have "fixed" this problem by raising it some. However, that got me thinking... what would happen if I raised it even more so that my legs would be straight (not bent at the knee) when the pedal was at the bottom? Would this give me increased power? Would this give me increased power?

Saddle height is a well known as an important factor for power generation on the bike.  There is however a sweet spot. Too low and you don't get to fully use the power range of your quadriceps.  Too high and you will over extend and lose power (as you are heading outside the optimal functional range).

Your optimal saddle height is also affected by your flexibility and position on the bike.  For example, if you are riding a road bike (that has a low slung cockpit position) hamstring flexibility becomes an important factor when determining your optimal saddle height.

  Have power tests been done to verify what level of leg extension produces the most power?

Yes.  This has been studied thoroughly. And while there are lots of general rules of thumb to get you into good starting place, the best possible saddle height is individual specific and depends on your own unique biomechanics (and can change over time).  Saddle setback (front/back position) is another important factor for power generation.

  Are there any problems allowing your leg to fully extend (straighten)?

Yes, this can lead to various repetitive stress injuries caused by how your body compensates for the saddle being too high. Different people may compensate in different ways and get different injuries as a result.

As a personal story, I was on recent short/fast/light tour when at in the final stretch I was getting some knee pains (outside, IT-band related) and I still had 120 km to finish the next day in order to catch a ferry and meet the kids in time for camping.  After much consternation that evening, I tried lowering the saddle by 0.5-1.0 cm (as I was using a different shoe/pedal combination than normal).  This completely alleviated the problem and I was able to ride the distance the next day and make the ferry sailing.

In the end the best advice is to make small changes and wait a bit to see the end effect. Record these changes in a notebook so you can look back and see the big picture. None of this is an exact science because each person has some aspect of their biomechanics that makes them unique.


What size are shimano MTB (wheel) hub ball bearings?

Rear hubs are generally quarter inch (9 per side, so 18) and front are generally 3/16 inch (10 per side, so 20). Obviously, if you're going to do this, order extras.

See this crib sheet from Sheldon Brown.


Replaced chain, now the chain falls onto the small chaining

At the point where the chainring teeth look anything like a sharktooth, they won't really work with a new chain without skipping and other issues. Even if it wasn't as extreme as that, it would still be accelerating wear on the new drivetrain parts. Replace the ring.


Replacing non-standard pedals on an exercise bike

9/16"x20tpi is the predominant modern size, and 1/2" also exists. On bicycles, 1/2"x20tpi is virtually always only found on one-piece cranks, but exercise bikes can do whatever. They are almost certainly 1/2".
1/2" cranks do not typically have enough material to be tapped to 9/16", but they're also not typically a 3-piece design as pictured. If yours did, this could be a way to do it. To cut new threads in a crank, extreme care has to be taken to have them stay on-axis, because any small deviation is easily felt by the rider. Doing that well, for me at least, means taking the cranks off and putting them in a vise so the angle the tap is going in can be monitored easily from all sides. If you go to a shop for this and they need to take apart that cover and whatever is under it to get the cranks off (unclear if that's the case), I would expect to pay a bit.
You can get 1/2" to 9/16" adapters. They are incredibly hokey, garbagey products, because they jack your Q out by something like an inch per side. But this is the cheap, simple way of getting clipless on it. Grease the threads and tighten them very well, because another reason why they're complete trash is they make the interface work with more leverage and flex than it likes.
The third route is figuring out a model from one of the SPD clone manufacturers that can have a 1/2" spindle from the same company hacked into it. I have not done this but I do know that those companies are not in the habit of having multiple spindle profiles when they don't need to, so I bet you could make it work if you figured out the right specimens. In other words, you're looking for a looseball VP or Wellgo or whatever set where everything from the thread shoulder onward is the same between it and some obtainable 1/2" spindles.
If the BB interface is a standard one, which is not a given, you may be able to replace the cranks altogether. You would need a captain crank on the right side, or one made from a left crank via helical insert. This is probably the most contrived and expensive way of doing it.


Newer frames tend to have serial numbers as a sticker rather than a stamp because it is cheaper. Having a stamped serial # or a sticker has almost nothing to do with the quality of the bicycle.


Is it ok to stretch a steel fork from 90mm to 100mm?

You can spread steel forks safely (never spread aluminum/carbon fiber), and its not a trivial task to do at home, since you need to keep the fork blades spaced symmetrically and you don't have the same type of leverage available for the rear triangle. Then re-bend the axle mounts, as Criggie points out in the comments.

Sheldon Brown has some tips on how to do it (pull the fork apart, check for alignment, use a rubber mallet when necessary), but I'd leave it to a shop if you can find one that can do it.


Nathan's comment is solid -
Assuming Stephan removed the keyed washer when he took off the lock nut...

How did it get this way?
It's hard to say, here are some possibilities.

It may have been cross threaded from the factory. Seems like a long way to cross thread something - all the way from the top of the steerer tube to it's current   location and then back up to almost the top. Cross threading usually results in some thread damage that should be visible in the steerer tube threads.
A previous owner may have cross threaded it. Same observations as option 1.
I can't think of anything besides cross threading (and Nathan's suggestion)

How to fix it?
First, check Nathan's thought - look for a keyed washer sitting on top of the race nut. It's labeled "Washer" in the diagram below.

Assuming cross thread - since you are 1/8 of an inch from the top with a rounded nut I'd look for a tool that will like a large vice grip to clamp on to turn in the last little bit. Some penetrating lubrication might help.
I'm worried about cutting the race off. It's hard to imagine how you can cut it without damaging the steerer tube threads. If you use some kind of a small cut off saw, don't go all the way through, make a couple cuts and experiment with a chisel to remove a section of the race it might not damage the threads.
I've read of people having success using heat to remove stuck nuts. I've never had any luck with it.

Maybe someone else will have a better suggestion.

If the threads on the steerer tube are OK all you'll need is a new adjustable race.
If not, you may be able to clean up the threads with the right threading die.
If not, you'll need a new fork


V brake tension adjusted by bending a wire

All but the cheapest V brake arms come with a spring tension adjustment screw. These screws push on the short end of the spring, but the springs are common to any V brake.

Models with adjustment screws still have the long arm of the spring alongside the caliper arm, it is still exposed and you can still bend it to make adjustments. So you could make do with your preferred method and take your pick of any quality brake you can find.

Turning the adjustment screw is a better way to do it, but there's nothing to stop you bending the spring on your own bike to achieve the same result.


Difference between road & mountain drivetrain

I think this is quite a broad question, so I'll highlight a few parts of the bike:

Seatposts/saddles: Probably interchangable

Forks: You wouldn't want to swap them, and chances are a beefy mountain fork wouldn't go into a road frame anyway, even if you could get the right headset.

Gearing: Road bikes typically have higher gearing than mountain bikes

There are larger chainrings on the crankset on a road bike - typically 52/39 or something or a 50/34 versus a big ring in the low 40s or 30s on a mountain bike.

The rear cassette is often smaller on a road bike as well (you won't see a 36t big rear cog on many road bikes, unless they're touring bikes).

Front derailleurs: FD's need to be shaped to the number of chainrings (typically 2, less so common 3 on a road bike vs often 3 on a mountain bike) as well as the size of the chainrings. For this reason (and in some cases the amount of cable pull needed to move the front derailleur) you can't mix road cranksets with mountain front derailleurs and mountain cranksets with road front derailleurs. On a mountain frame, you probably can't clear a road double if you were to mount it on, and you may have derailleur mounting issues when putting a mountain crankset on a road frame in some cases.

Rear derailleurs: Until 10 speed, you could swap them around when you stuck within the brand (then they introduced different cable pulls introducing shifter incompatibilites, so road shifters have to be paired with road derailleurs and similarly for mountain). The mountain rear derailleurs can shift larger rear cogs than road ones.

Cassettes: You can interchange them if you want in a lot of cases (touring road bikes often use big rear cogs).

Shifters: The front derailleur needs to be matched to road/mountain shifter. Rear derailleur will need to be matched if >=10 speed. Friction shifters always work.

Wheels: Mountain rims are often wider to support wider tires at lower pressures and are usually built to be more robust. Your hub widths are often the same, but mountain axles can cause compatibility issues (not just your usual QR) with different frames. Note 700c = 29". Often wheels built for tougher road riding (e.g. touring) use mountain bike hubs.

Tires: Mountain tires are typically fatter than road tires.

Cables/Cable Housings: You can use the same types.

Handlebars: Mountain and Road bars have different diameters, so brake levers and shifters designed for one will not fit on the other.

Brakes: Typically, road brakes (mechanical disc brakes for road, caliper brakes, cantilever brakes) are short pull while mountain brakes are often long pull (v-brakes, mechanical disc brakes). This means you require a travel agent or special levers to run v-brakes or certain mechanical disc brakes on a road bike. Hydraulic systems are quite new on road bikes. Since you can't mount the levers onto a mountain bar, exchanging them is somewhat moot at this point.

Racks+fenders: These are wheel size and disc/not disc specific. Read the directions on the rack+fenders.

Generally, road stuff is lighter than mountain stuff. Probably less durable in a crash though.

Now to part 2 of the question: What can you change on a bike to improve your commute? This question has been asked on SE a bunch of times, but typically the answer for commuting on a mountain bike is to lock out your suspension if you can (or switch to a rigid fork) and fit slick tires. You could also try a smaller cassette if you want, but other than that, you're going to want to get a new bike. If you have a road bike, you sometimes will want to fit a big cassette so you have lower gears available (you may need a new chain, and to make sure all the capacities of the derailleurs are within spec, else you may need a new rear derailleur) and bigger tires to make things more comfortable.


Can't shift front gear, despite loosening, tightening, etc. What could be wrong?

First note that if you get full movement in your rear gear shift you will probably have all the range you need. I think this would be EASIER than working on front derailleur. SO I recommend working on your Secondary Problem first! :-)

NOTE: Allow plenty of time for fiddling with your gears. Do it in a warm dry place when you have time so you can learn how things work in a relaxed manner. The less work you have to do the better! :-) Take it step-by-step. Adjusting loads of things in one go without having done it before could leave you with gears not working at all!

Main Problem
Three sensible things and one that is not for the faint-hearted:

CLEAN and OIL the front derailleur. Does the front derailleur itself move up and down (in and out) if you push and pull it with your hand (or you might need to use foot!)? It should move babck itself pulled by the spring. Clean the derailleur - it can get clogged with dirt - and oil it after cleaning. Because your cable moves but your derailleur doesn't this is the first thing to do.
CLEAN and OIL the cable Does gear cable move freely and pull on the derailleur properly? If you pull on the cable strongly with your (gloved) hand does the derailleur move up and down? Rust or dirt in cable might cause it to get stuck. Clear out cable with oil and take it off bike and lots of manual movement. Replace the cable if it is rusty or damaged.
Adjust the limit screws on front derailleur. The small screws H-stop and L-stop. One is top limit, the other is the bottom limit. They prevent the chain jumping beyond the rings and getting stuck - which is bad.
NOTE: Lowest gear is small cog on front, large cog on rear.
NOTE: Highest gear is large cog on front, small cog on rear.

turn your bike upside-down or put on stand or lift where you can freely pedal and also operate the gear lever

NOTE: You can do L-stop or H-stop in whichever order you prefer. It doesn't really matter.

move gear lever to lowest setting
pedal(gently) and adjust L screw until chain moves onto lowest gear (smallest cog)
pedal(gently) and check you can click up and down from lowest into next gear
move gear lever to highest setting
pedal(gently) and adjust H screw until chain moves onto highest gear (biggest cog)
pedal(gently) and check you can click up and down from highest into next gear

SECOND-LAST STEP: pedal(gently) and move to highest and lowest gear. You may have to adjust the stops again.

FINALLY: pedal(gently) and click all the way up and down through the gears.  If something is not right then you can repeat the process from start - you will soon get a better feeling for when the stop is adjusted correctly.

More info: http://sheldonbrown.com/derailer-adjustment.html http://www.instructables.com/id/How-To-Properly-Adjust-The-Front-Derailleur-On-You/step3/Front-Derailleur-Limit-Screw-Settings/

(Probably better NOT do this!) It is possible that the front derailleur attachment to frame is not right. Maybe it got knocked. You could unscrew and adjust height on frame or angle. BUT it is VERY tricky to get things working again if you move it! The attachment is usually very tight and not prone to being knocked into the wrong angle.

Note it is tricky to get the limit screws adjusted properly. But learn how to do it and it's very useful and will save you time with any bike you own.

Secondary Problem Which I think is both EASIER to improve and will give you more BENEFIT.
Similar three things (1. 2. and 4.):

CLEAN and OIL the rear derailleur. Springs, moving parts, screws and cogs. This will help loosen things up and gear cable will be able to pull better.

Check movement of rear derailleur. Move the derailleur in and out using your hand or foot. Does it line up with gear cogs correctly? The rear derailleur is prone to getting a bit bent or twisted. Some brute force can help (of course applied in the right place in a gentle mechanically sympathetic way!).
CLEAN and OIL the cable As in main problem. I think your rear gear cable is moving okay though.
Adjust the limit screws on rear derailleur. Small screws H and L again and another indexing adjustment screw. THIS is probably what will actually solve your problem!.
NOTE: Lowest gear is small cog on front, large cog on rear.
NOTE: Highest gear is large cog on front, small cog on rear.

turn your bike upside-down or put on stand or lift where you can freely pedal and also operate the gear lever
move gear lever to lowest setting
pedal(gently) and adjust L screw until chain moves onto lowest gear (biggest cog)
pedal(gently) and check you can click up and down from lowest into next gear
move gear lever to highest setting
pedal(gently) and adjust H screw until chain moves onto highest gear (smallest cog)
pedal(gently) and check you can click up and down from highest into next gear

SECOND-LAST STEP: pedal(gently) and move to highest and lowest gear. You may have to adjust the stops again.
You can repeat the process from start - you will soon get a better feeling for when the stop is adjusted correctly.

FINALLY: pedal(gently) and click all the way up and down through the gears. If chain is not happy to stay on cog for some gears then adjust the indexing screw.

More info: http://sheldonbrown.com/derailer-adjustment.html and http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur


How to assess safety of carbon frame after crash?

The first thing is to clean the entire frame and fork very carefully and look for cracks or irregularities. I like to use something like a squirt bottle silicone cleaner/polish for this, along with a microfiber finishing rag, because it kind of normalizes the surface and makes things easier to pick out. Look extra carefully all around the joints, particular of the chain and seatstays, which is a place where rear end impacts are particularly likely to cause cracking on carbon road bikes in my experience.

If you find anything where you can't tell whether it's a crack in the frame or just the paint, chip away the paint to look underneath.

Presuming you find nothing, you're faced with an ambiguity that is best considered to be part of the cost of admission to carbon bikes. In other fields there are ways of using x-rays to look for unseen damage to carbon fiber structures, but it's considered impractical for bikes cost-wise and is not done. All anyone can do is guess.


How do you remember which rack you have left your bike in?

Use your phone to take a photo of your bike location, being sure to get some easy to find landmarks in the photo as well. E.g. if you had just taken the photo above and your bike is the front centre one, those two trees should be fairly easy to find again when you come back.

If it still takes a while to find (or the search area is very big) and your phone has GPS, you can probably tag the photo with the location as well.


How to pick mountain bike pedals (platform)?

We can't recommend which model to buy, but some good things to keep in mind are the following.

Platform size: Width and thickness, if you have wide feet you may
want a slighter wider pedal. And being overly thick means you will
probably catch them on rocks more often.
Pins: Removable metal pins or molded in pins, i prefer removable metal ones, which are usually found on slightly more expensive pedals. However when you smack your shin on a metal pin it does quit a bit more damage than a plastic one and they can also scratch your legs up when standing over your bike. Some metal pins are also hollow, improving both grip and leg shredding ability. Some are very sharp and some are well rounded.
Bearings: Sealed or loose ball, cartidge or DU Sleeve. Sealed is generally better as it will keep dirt and water out making sure your pedals are buttery smooth. A lot of people are unfamiliar with DU sleeves but they are actually in a lot of different pedals, sometimes under a different name. Basically they are a Teflon impregnated tube that is in contact with another tube of the same material, the have a longer break in period but both self lubricate and are virtually maintenance free. Many pedal manufacturers use both a sealed cartridge bearing and a DU sleeve.
Concave or Flat: This is more of a personal preference, but a concave (curved inward) surface is suppose to help keep your feet planted and increase traction on the pedal.
Material: Metal or composite, generally metal will last longer, and the pins will not be worn down or sheered off on rocks if they scrape. But an expensive composite pedal could certainly outlast a very cheap metal one. There are also composite pedals with metal pins, offering low weight and good grip.
Price: Kinda obvious, i will say this though, there are pedals out there that are every bit as good as other 3 times the price. Just because they cost $100 and have a name brand doesn't necessarily mean they have any more features or durability.

These are what i ride and i have zero complaints. Love em, super thin, and their affordable should i ever break one. Best thing this company makes in my humble opinion. A good example of a metal pinned pedal

And here is an example of a plastic or composite pedal with molded in pins.

You can easily see the difference in thickness between these two. The concave isn't as obvious due to the angles but you can see how the curve downward toward the center of the pedal creating a bit of a dish effect. While the Origin8 pedals in red are rather flat in comparison.

Lastly, what type of riding your doing will also have somewhat of an impact, generally dirt jumping riders prefer a stiffer axle so that the pedal doesn't spin when they are air born with their feet off the pedals. General MTB riding this is not the case and not as important.


That bike is a good find. The double-butted frames are more desirable than the TIG welded later models. It's unclear to me exactly why other than a general assumption of it being a higher quality frame.

As mentioned in the comments, something must be done to inhibit the continued oxidation of the cro-moly steel frame. Generally, two things must be accomplished: complete removal of the rust that has already formed followed by refinishing the now rust-free areas of bare metal with a high quality primer and paint.  Keep in mind that the best paint jobs result from meticulous surface prep.  After completely removing the rusty areas, use ever-finer grades of sandpaper in a stepwise fashion to bring perfect smoothness to the areas to be painted.  Removal of all dust, dirt and oils--any contaminants--–with a mineral spirits based pre-finish product just prior to priming is a key step that is often under emphasized but vitally important for a successful end-result. Here are some example videos/tutorials on that aspect of restoration.

I'd suggest the subsequent phase of a project like this is determining how the bike will be used a majority of the time.  This helps form the pool of possible component combinations to best suit the intended use. A good place to start would be whether the set up will have flat bars or drops, and the size and type of crankset.  These decisions then lead to your pool of derailleur/shifter options.

The Multitrack is a versatile creation that came stock with  a Shimano mountain power train that spun road- like 700c wheels and 38mm tires, which is approximately 10-13mm wider than road standard.  I'm certain the BB shell is 68mm and threaded  and a modern compact road crankset with outboard BB bearings should work equally as well as a mountain triple spinning around a square taper or splined cartridge BB.

This will be a fun and interesting project.  I love the fact that a quality machine may realize it's potential as a source of transportation, recreation and joy for multiple generations.


What to do when a snake is in front of you?

Stop. Back up if necessary. Don't risk running over it. Snakes almost never chase people, they will only attack if they're cornered or you're lying very still (for very large snakes that eat things the size of people).

Running over a snake is probably your worst approach if you don't want to get bitten. Not only do you have to be very close to the snake, you're going out of your way to threaten it. Almost any animal in that situation will try to attack you, purely to stop you killing them.

I've seen several snakes, one on my commute route. For me that's a chance to stop and go "Wow! A snake!" and maybe get my camera out so I can take a photo from a safe distance. But even snakes that aren't venomous are best left alone. Either because they're wild animals that you respect and want to encourage, or because the gap between non-venomous and harmless is significant. A bite or accidental impact from a snake can still injure you.

Also, many are protected, and I'm not sure whether being bitten by a venomous snake is actually worse than being prosecuted for interfering with one.


Five flats in 4 months on new Giant Contend3 (XL)?

For road bike tyres you need a pressure gauge -- pumped up so they feel hard to the touch, the tyres could well be at their lower pressure limit. You say it's an XL frame; guessing that you're normally proportioned that could be a fair bit of weight on the back in particular (I'm at the big end for XL bikes, so I don't mean anything negative).  That makes it more important to pump the tyres up properly than for a lighter rider (the ideal pressure is higher and therefore air is lost faster).  It also makes it more important to look after the bike over potholes etc., by standing up on the pedals if you can't avoid the hit.

That bike ships with 25mm tyres. Running just a touch bigger (28mm) can make a big difference to how long the tyres hold pressure (as can thicker tubes or butyl instead of latex).  Depending on the rim width you might win in other ways on a bigger tyre too (absorbing shocks). What width tyres did your old bikes have? If not all of your punctures are pinch flats, tougher tyres would be worth it too.


Contradiction! Which back posture is correct for road biking?

The main issue with the posture images you included (shown again below) is that both positions represent extreme positions and both are likely problematic, despite one being labeled as correct. The image on the left has put the back into hyper flexion, over-recruited the lower abs and tilted the pelvis backwards, this position will likely cause breathing and back issues. The image on the right has contorted the upper back, splaying the rib cage open and turned off recruitment of the lower abs.  The contorted rib cage will likely impact breathing as well.

The one thing that image on the right got correct, is that your pelvis should be titled slightly forward. Ideally, you want the pelvis tilted slightly forward, with a smooth transition into a flattened back. A good example of forward pelvis tilt with a flattened back is the blue rider pictured in the next picture featured).  His pelvis is tilted forward (similar to the "correct (but not really correct)" image above, but he also has some mid back curvature with a smooth transition from pelvis to mid back. This makes it easier to engage your core muscles better to support your upper body.  Try sitting in a chair, bending forward a bit (while keeping your feet off the ground) and see how easy or hard it is to support your upper body when rolling the top of your hips forward or backwards. Flattening the upper back is also very important for breathing which we touch on further below.

This type of rider position is often seen in professional riders, and is explained in more detail in "Bike Fit" by Phil Burt (lead physiotherapist for British Cycling and a consultant physio for Team Sky):

POSTURE
Posture is the maintenance of a certain body position and requires appropriate joint mobility, joint/muscle coordination and muscular endurance.  Limits in any of these elements can result in postural irregularities.  Good posture on the bike required good flexibility through the hamstrings and the glutei muscles:  this allows the pelvis to roll forward, keeping the back in a straight position while reaching the handlebars.
One major factor limiting the back's ability to remain relatively straight while on a bicycle is thoracic immobility: lack of movement in the middle of the spine normally results in the spine flexing too much.  Excessive spinal flexion while on a bicycle will limit breathing and compromise your ability to stability your spine for torque production to the pedals.
-Phil Burt, Bike Fit

Breathing
A second key consideration in cycling is breathing, which can be impacted by posture:

There are both anatomical and bicycle limiters to ventilation. An example of an anatomical limiter to ventilation would be being too flexed through the thoracic spine (that is, bent forward), not allowing the ribcage to expand sufficiently.
-Phil Burt, Bike Fit

In both posture positions in the top photo, neither have a flat back, which will impact the effectiveness of breathing. In the photo on the left, the ribcage is flexed through the thoracic region as described in the quote above. In the second image on the right the thoracic region is again being flexed, but in the opposite  direction. This will again impact the efficiency of ventilation compared to a flattened back.
Not only is effective ventilation important, but inefficient ventilation mechanics can cause secondary breathing muscles to be over worked which can lead to pain.  (Breathing is incredibly important, your body will find a way to draw breath, even through poor mechanics if necessary, exhausting muscle not "designed" for such extended usage scenarios):

Ventilation for the endurance athlete is most effectively performed through diaphragmatic breathing, in which contraction and relaxation of the diaphragm pulls and pushes air from the lungs. Secondary muscles of ventilation include the inter-costals (between the ribs), the abdominal musculature, the trapezius, the levator scapulae and the scalenes. If diaphragmatic breathing is compromised these secondary muscles can become chronically overworked leading to myofascial type pain (i.e., pain between the muscle and the muscle covering). This is often seen in the upper neck and shoulder muscles.
-Phil Burt, Bike Fit

No there is no way to know whether posture and ventilation mechanics are responsible for the OP's neck pain, but I think both of the posture pictured in the top posture photos could lead to such problems.
Endurance position, same principle
Finally, race positions are obviously not the best position for everyone! Here is another example of pelvis titled forward with a flat back, but in a more sustainable "endurance" type position which have a higher front end stack and a more upright position:

The rider also has a good elbow bend, straight wrists, and relaxed shoulders. Overall, a great position.


Widely available cassette cogs: recommendations?

11-28 through 11-46 cassettes are all pretty ubiquitous these days.

Sprocket sizes for a few cassettes in this range:

11-12-13-14-15-17-19-21-23-25-28

11-12-13-14-15-17-19-21-24-27-30

11-12-13-14-16-18-20-22-25-28-32

11-13-15-17-19-21-23-25-27-30-34

11-13-15-17-19-21-24-27-31-35-40

11-13-15-17-19-21-24-28-32-37-42

Just based on how common they are, I'd say that choosing somewhere in the range 12 - 28 teeth will be safe. However, larger sprockets are attached to a spider and some smaller ones have a built-in spacer. Fundamentally there are probably many issues with choosing to use cassette specific sprockets. You might be better off looking an single speed or internally geared hub sprockets, which do exist in non-freewheel versions for 3/32" chain as well as 1/4".

Another alternative is to look at the small end of chainrings in common bolt patterns, 22, 24 and 26 teeth are pretty common. There are plenty of 3x7, 8, and 9 groupsets around for inexpensive bikes and that is not likely to change soon. Chainrings are usually flat and can be purchased individually.