What are the effects of completely filling tires with water instead of air? As absurd as it sounds, I was curious as to how a bike would handle with the front tire filled with water.  I wonder if steep hill climbs would be easier (particularly for a mountain bike):

1) to bring the center weight forward

2) to use the increase rotational momentum to carry the speed through to the next pedal stroke.

I happened to do just that.

I took an old hand pump and an inner tube to the bath tub.  Submerged the pump and pre-filled the tube with water, complete with burping out any air bubbles.  With the tube moderately full and free from air, I put it on the rim with the tire.  Then the final pressure up.

The first thing to notice is that the pump operates with lots of resistance (water flows a lot slower than air through those tiny parts).

As I pushed each stroke of the pump, the resistance difficult yet constant.  I kind of expected the resistance to increase as I pressured up the tire, but it didn't.  It was a solid stopping point, halfway through the last stroke the tire wouldn't take any more water. (I shouldn't have been surprised, water is one of the least compressible substances around!)

Now out for a ride to test this out!

Indeed to carry the bike the front was a bit heavier (heavier is exactly what most cyclists would not want; but hey, lets see if there's some benefits).

Oddly, the bike didn't feel all that different.  Just slightly front heavy.  But once I got some speed the steering became really quite stable.  A ride through the forest and I could quickly pin point my leans for corners, it was soooo smooth!  Like the steering of a motorbike; I assume the extra rotational inertia in the front wheel added to the smoothing gyroscopic effect.

Mucking about, I tried a wheelie.  It took a bit of getting used to for lifting it up, but once up it was also very very smooth.  I was never that good an wheelies, but now I seemed to be able to ride for as long as I wanted.  Try balancing a baseball bat with the heavy side down, it's actually much easier with more weight at the top!  And the extra gyroscopic effect made it easier to steer the wheelie.

When stopped at a light or something, pick up the front tire and it would slowly start to rotate on it's own.

It was fun, so I kept it.

The next phenomenon was a puncture.  sure enough, one day riding on a nice sunny day... I feel tiny sprinkles of water; I had a tiny tiny leak and I was actually spraying a very fine stream.  The tire hadn't lost much though, so I double timed it to my destination in hopes of avoiding changing in the field.  On arrival, the tire seemed really quite full still.  When off the bike the tire really wasn't getting flat. I left it.  I continued to ride for a week or so, sometimes the leak would come back... sometimes it would go away.

I'm speculating, as I only did this once... but it occurred to me that with water being incompressible, the small amount of leaking water was very little volume but nearly all of the pressure.  The tire was still full and held it's shape, but no pressure to force the leak when I wasn't on it (it was obviously a very small leak).

Eventually I had to add some air, now and again (too lazy to put water in, and too curious to see how bad the water/air mix would be).  Soon the water/air mix was sloshing inside and causing a lot of resistance, and that became the end of my experiment.

In the end I did not see any improvement for hill climbs, or maintaining pedal momentum; only wheelies and cornering.


Six speed chain on an eight speed bike So in the shop they asked me "what chain do you need" and I said 7. They said "you could try this 6-speed, it is half the price of a 7, and we put it on 7-speeds all the time". I said "ok", only to determine later that my bike is 8-speed. (Excuse: I never use the several highest cogs).

I know "higher-speed" means just that the chain is thinner, fitting the recommended chainring, plus any other with less cogs (because there is more space between the cogs).

And, as expected, my bike now makes all kinds of clicking noises and skips. However, upon inspection, the chain does not rub the chainrings. It fits tight, but does not touch the other chainrings.

I will probably replace the chain for a correct one, but before that I would like to know what is the cause of the problem (the skipping).

EDIT: some more detail
We are talking a $300, used regularly for three years. Of it, only the chain has been replaced - twice.

If needed, I will post a photo tonight. Just ask in the comments!

The skipping will always be because of the chain touching on the other cogs, or trying to slip back down from the pull of the rear derailleur. The chain is too wide and, as you already know, is doing one or the other. It might not be evident from looking at the cogs while riding as the chain is fed from underneath when you pedal, so the clicking from the chain moving may only be visible when the bike is upside down.

If you have a reasonable quality shifters/cables/mech then you should be able to just about get away with it with some really fine adjustment.

The difference between 6, 7, 8 and 9 speed is actually the spacing between the cogs, and not the width of the cogs themselves. Hence the need for thinner chains.

Edit: I haven't got comment everywhere ability yet, but as suggested below, you should make sure your chain is the correct length. The recognised method for this is to wrap the chain around the largest cog at the front, the largest cog at the back, pull tight and then add two links (or 3 if it ended up with two inner links).

This generally ends up being shorter than what you had originally, but is correct.


Why isn't the chain on the rear gear in biggest cog for lowest gear I have bought a bike few days ago and I am a new rider as an adult. And, I am a little confused as my rear brake has 7 cogs but the chain is on the second from top cog.

Shouldnt it be on the biggest cog in gear in 1? If so how would I fix this?

Similarly, the indicator looks like it is in between  gear 1 and 2.

The front cog when in gear 2 also
makes a grinding noise.

Please help me, I am a newbie and would appreciate the help.

**UPDATE: Adjusting the front derailleur **

I have followed accordingly, as per answer below, and found on the front cog the chain looks to be scraping against the second/middle cog of the front three.

Putting the Front gear in 2 and spinning the pedals the chain doesn't go in the second cog. But, when I was riding it this morning, felt like I was in gear 2 for this gear.

Also, trying to adjust the derailleur on on the vertical axis - up and down; the screw seems like it is just spinning and no movement. I can easily see the horizontal movement just not the vertical.

I am lost as to what else needs to be done now.

You rear derailleur is probably just adjusted improperly. The indexing adjustment lines up the derailleur with each sprocket. Your's is so far out that when the shifter shows 1, the chain is on sprocket 2. The grinding noise is because the derailleur is trying to push the chain onto sprocket 1 but cannot move quite far enough.

The Park Tool company has great articles and videos that provide step by step procedures for both rear and front derailleur adjustment. Follow those and see if that fixes the issue.

Some other observations:

Your rear quick release is in backwards. The lever should be on the left side of the bike. If it's on the right side it may interfere with the derailleur. Also you may not be able to close it properly with the derailleur in the way.

You should also trim and re-cap the derailleur cable. The long cable end you have now could catch between the sprockets and chain, or in the derailleur cage which could jam the drivetrain and throw you off the bike.


Fastest way to get faster up hill There's a 2.4km, fairly gentle hill near me which I want to get quite a bit faster on.

The traditional answer to my question is likely to be 'Go up the hill more often', but I also have a turbo trainer. I was wondering if it's more useful to do intense intervals on the turbo or just keep going up the hill on a regular basis? The hill is definitely more fun than turbo trainer but I want to get stronger and faster as fast as possible.

What's the answer here?

Some more background: I'm ~78Kg in weight, 6ft tall. My PR is 4:23 on this segment/climb. My first goal is to beat some guy I know who is 15s faster.. I think I can do this just by getting a decent run up and having a good day.. however that brings me on to the real challenge which is getting a lot faster! Ultimately I'd like to knock off 31s. Strava link: https://www.strava.com/segments/1525252/

I get out on my bike perhaps 2x or 3x a week for a 'proper' ride. Other than that I do 100km of commuting on a slower commuter bike. I'm 34yrs old and sometimes do some running and kettlebell exercises too. I dream of being massively powerful but due to time constraints I don't think that'll ever happen lol.

Unfortunately, there is a fairly straight forward reason why you actually need to ride hills in order to get faster at them: crank inertial load.

We have two main types of skeletal muscles. (Skeletal muscles are responsible for our locomotion and movements, cardiac and smooth muscles make up the other muscle types in our the body). The two main skeletal types  are slow twitch which has slower contractile speed, lower force, but higher endurance and fast twitch which has a faster contractile speed, higher force, but lower endurance. Fast twitch can be further broken down into an additional 3 sub-types, which again vary from each other by contractile speeds and forces generated.   Each person has a unique make-up of these skeletal muscle type which is controlled largely by genetics, but the relative strengths of each type can also be trained plus there is some evidence for inter-conversion of the fast twitch muscle types through training.

This gets us to hill climbing.  The conditions experienced by your skeletal muscle when climbing is very different from riding on the flat. On the flat you are typically carrying a lot of momentum (kinetic energy). If you stop pedalling you will still be carrying a lot of speed and will not slow down much immediately after you stop. As such you have all this energy which helps to overcome the drag and rolling resistance. In order to accelerate you will need a quick burst of work which means you need to fire your muscles more quickly in order to perform sufficient work in a short enough time period. These conditions are more favourable to including more fast twitch fibers (although all fiber types will still be contributing).   Conversely, when climbing you have less kinetic energy. If you stop pedalling you will slow down much quicker. These conditions are more favourable to longer contraction times, which in turn favours the use of slow twitch muscles over fast twitch.

This all has important consequences when looking at replicating riding conditions with indoor trainers. This quote from R Chung (who is a frequent contributor on bicycles.se) summarizes nicely why this is the case:

  No turbo currently on the market can adequately replicate the forces you experience while climbing. Mostly, that's because hills vary in steepness, so the power and inertia vary, while most turbos (all mechanical turbos and many electronic turbos) have a fixed relationship between wheel speed and power, and all have fixed inertial load. Some electronically-controlled turbos can vary the relationship between wheel speed and power (typically, by something they might call "slope") but none vary the inertial load.

  So when you're training on a turbo, forget about cadence, or climbing. You can't replicate it. What you can replicate is the range of power you need to produce. So just focus on that. If you have a power meter this is easier but if you don't just focus on wheel speed, even if the wheel speed isn't representative of the wheel speed you'll use while climbing.

Unfortunately, its not just "Turbo trainers" most trainers on the market cannot sufficient replicate the inertial loads experienced when climbing. These are better suited to replicating riding flats and as such provide a poor substitute for actually getting out and climbing real hills because you are training muscle firing patterns that are much different than what is needed to climb efficiently.

Finally, Cycling Tips has a good article summarizing the differences in how our muscle work when climbing versus riding flats.


5 Gears usable out of 6 I have mountain bike which is around 1.5 years old. When I bought it, I used it without any hassles and all was fine. But one day I overshifted the friction shifter and the shifter was bent. Now it won't shift to chain levels. I knew that friction was of no use and I didn't look into this matter. A year passed, and now I am wondering about that issue because one of my friend bought a new cycle and he shows me, and I get burned up.

The main issue is that when I brought the cycle I didn't knew so much about gears. And when I shift gears to the 6th gear, it won't shift at all. I have a 18 speed bike, and out of them I can only use 15 gears. When I shift to 1st gear, one gear remains to be shifted. This was the problem since I bought the bike. But now I am jealous of my friend. And, my friction shifter is out of order. It is bent and not properly adjusted. When I shift to 1st gear the chain falls down, and the shifter rubs with the chain. So I can only shift between 5-2 gears. Please help me, I am not so expert in gears.

A bike 18 months old is very unlikely to have a friction shifter.  Did you mean its an older bike that you bought 18 months ago?

Raise the bike off the ground, either in a stand or hang it from a tree branch or rafters by rope.  Then slowly pedal with your hand while pulling on the inner gear wire whereever you can get to it (front downtube is normal)

You should see the Rear Derailleur move through its whole arc of motion and the gear change should happen.  This would isolate the problem to your shifter's mechanism.

If the gear change doesn't happen, the problem is at the back.

Consider posting some photos once you've had a closer look.


How to measure and treat BSA bottom bracket housing misalignment? I own an old Raleigh steel frame ('89) and wanted to install a cartridge bottom bracket (Shimano UN55).

I noticed it was difficult to fit it in the housing. When installed, the square taper shaft showed considerably more friction when turned.

Also, when I took the BB out again I saw rubbing marks on one side of the inner face of the lock ring, but only on one side. The threading itself is not damaged. When installing only one side of the BB, everything goes in smoothly.

To me it looks as if the BB housing is somehow misaligned. How do I measure it? And how do I treat it?

The threads on bottom bracket shells can have angular misalignment. The threads are typically cut in two operations, one from each side. If the shell is not aligned properly in the jig when the threads are cut misalignment is the result.

Misalignment should be fairly easy to diagnose at least.

Install the cartridge only from the drive side making sure to not cross thread it. If you look at the non drive side you should be able to see if the body of the cartridge is centered in the shell on that side. That will tell you if the drive side thread is aligned.

You can also install the lockring and see if its flange lines up with the edge of the shell (this is not a great indicator of thread misalignment , because the edge of the shell may not be true).


Derailleur out of alignment after cable snapped The front derailleur cable snapped on a friend's bike, she shifted it with her hand to a rideable position, and rode for a few weeks. She asked me for help replacing the cable, though when I replaced it, I realized it couldn't shift the cable onto the big ring, as the derailleur cage touches the inside of the larger chainring, instead of guiding the cable above it. [[EDIT: Touches the chainguard, as pointed out below]].

On visual inspection, it seems like the derailleur is installed too close to the chainring, and should be 1-2mm higher. The thing that seemed obvious to do, but very likely wrong, would be to unscrew the derailleur hanger at the frame, lift it 1-2mm, and reclamp it. But this is a 30 year old bike, where the derailleur surely has never been moved. I'm sure I'd be making things worse if I tried this.

Is it possible that the cage is bent somewhere else, and there's another way to adjust it? Photos attached.

The derailleur cage is not interfering with the larger chainring, it's hitting the chainguard.

As you say, its unlikely the derailleur slipped down the seat tube a few mm. Seat tube clamp mounts hold on quite tightly, and if they do move you typically are able to see a line on the frame where dirt accumulated next to the clamp. The parallelogram links are pretty robust and don't typically get twisted or bent. The cage itself may get tweaked but you'd see scratches if there had been an impact.

The derailleur might just have rotated around the frame very slightly causing one end of the cage to contact the guard. You'll be able to see if this is the case because the cage will not be parallel to the chainrings.

If the derailleur has not moved I suspect that the cage is actually able to move far enough outboard to shift the chain to the big ring before it hits the chainguard. If it will not shift the chain, moving the derailleur up a millimeter or two so it just clears the guard will probably be just fine.

It's probably worth running through a full front derailleur setup process to make sure you have the limits set correctly. Park Tool has a great web page and video that walks you through the whole process step by step.

https://www.parktool.com/blog/repair-help/front-derailleur-adjustment


Cassette & crank combo for commuting Okay so I've been reading about gear ratios and what not all morning and I can't make any sense of it. Some of it is registering but it's still kind of over my head.

I'm ordering a Tiagra group set for my commuter bike.  It will be around 10-15 miles a day (5 days a week) carrying approximately 35 pounds on panniers.  The commute will be mostly flat, couple small hills and some easy elevation increases.

I used to cycle quite a lot (200 mi/wk) but haven't ridden in a year due to time constraints.

So my options for the cassette are:

11-25
12-28
12-30

From my understanding I would want to go with either an 11-25 or 12-28.  The 11-25 would be more for speed/power and 12-28 would offer a wider range of gears (i.e. lower gears for climbing hills)?

Crankset options:

39/52
34/50 (Compact)

Crankset I have no idea about, this is where I keep getting lost with everything.

Any advice or recommendations would be very much appreciated.

50x12 lets you do about 55km/h (35mph) pedalling at 100rpm. Since you say you're commuting, mostly on the flat, with a non-trivial load, you're not going to get any real use out of a bigger gear than that, so an 11t cog or 52t chain ring won't have any advantage.  However, having a small ring of 39t or a biggest cog of 25t will hurt you if you have any steepish hills (say, 5% or more).

That points towards a compact crankset and either the 12-28 or 12-30. Honestly, there's not much difference between the two for the terrain you describe.  The 12-30 gives you an extra big gear, which is nice if you're going up any big hills but you say you're not. The 12-28 has slightly shorter gaps between the cogs, which makes it slightly more likely that you'll have that perfect gear at any given time.

You might also want to consider secondary uses of the bike.  If you think you might start going for rides at the weekend, the presence or absence of hills on those rides might push you towards the 12-30 or the 12-28.


Period of adaptation between a mountain bike and a road bike I am a casual rider and I am starting to consider switching from a mountain bike to a road bike. My main concern is that I don't ride enough to adapt to a road bike and thus is not worth the switch.

Because of the different position, new muscles will probably be used, I may not be flexible enough, etc. I will need some time to feel as good on a road bike as on a mountain bike. How long will it take if I only ride once a week 40-70 km (25-45 mi)?

I am aware that it depends a lot on the cyclist, my question is more about whether it will take 2 weeks, 6 months, or if it's not enough to get used to a road bike.

I'm an MTB rider who occasionally got into a Road Bike for 60 km rides. (5 hours aprox). From experience I would advise several short rides before a very long one. Ride until you feel uncomfortable and keep going for another 10-15 minutes but don't let yourself get into [severe] pain.

For example: Get two 30+ minutes a week for 2 weeks, then grow to two 45+ minute rides a week for another two weeks. So in a month (+/-) you'd be ready for a 1.5 hour weekend ride. After that you grow as you see fit. (These numbers are just a rough reference).

Also, if you are a casual (read non competitive) rider, do not set the bike for the most aggressive position, that is, set the stem angled upwards and choose a short one, place the stem spacers bellow the stem to raise the handlebar.

As you get more used to the bike, you may want to progressively make changes (adjustments or component swaps) towards a more aerodynamic position, but for starters, I recommend setting the handlebar such that the flat part of the handlebar is at the same distance and relative height from the saddle as your MTB (or as close as possible).

Indeed MTB and Road bike geometries are very different, but the measurements I found to be more relevant (regarding pain from not being used to them) are the effective distance from the saddle to the grip point, and the height difference among them.

That means that measuring top tube, stem, etc. is a bit fuzzy and of less practical value for the casual rider. Instead, Measure the distance from the center of the saddle (roughly where your sit bones rest while riding) to the point where you actually grip the handlebar.

For MTB you got only one grip position, but for road you have at least four: On the flats, on the drops, on the hoods and on the "corners" of the handlebar. Most frequently the rider that comes from an MTB geometry would spend more time on the flats and will progress towards the hoods.

With that in mind, if the road bike has the chosen grip position further away from the saddle and/or lower (compared to the MTB previusly ridden) then the torso will be at a lower angle, puting more weight on the arms and needing more effort to keep the head up.

Regarding this last point: Use a road specific helmet or remove the visor from the MTB one. This is because the visor usually found on MTB helmets is designed to be used with an upright head. On a road bike you would have your head leaned forward, so helmet's visor, if any, gets in the way, forcing you to raise up your head, putting additional strain on the muscles of the back of the neck.


Cables for my rear gears do not work The rear derailleur on my Huffy 21 speed bicycle does not switch anymore. It will click and turn, but the gear won't switch. When I attempt to force it manually it switches back to the biggest gear (smallest cog?). Please help, it's my only mode of transportation.

If the shifter does not move the derailleur at all, then either:

A cable housing has come free from the shifter unit, frame boss or derailleur
A cable end has detached from the shifter
A cable end has detached from the derailleur
The cable has broken (least likely)

Basic things you can do to find the problem:

Find an exposed bit of cable (the inner silver cable, not the black housing) on the frame somewhere. It should be taught and not loose.
Inspect the shifter cable run from the shifter to the derailleur, make sure the cable housing is inserted into the shifter unit, all frame bosses and the derailleur.
Find an exposed bit of cable near the derailleur, grab hold if it (using pliers will help), put a little tension on it and operate the shifter. If the cable moves it's attached to the shifter.

If the cable is moving near the derailleur when the shifter is operated, check the cable is attached to the derailleur.


Can i use v brakes on racing bike rims? i fitted a set of cheap "thin" (racing bike size) rims with 32 mm tyres. the fork allows even bigger tyres to be mounted. is it a problem if i fit the bike with Deore LX v-brakes ? will it brake decently ? and what handles would u recommend?

32mm tires with v-brakes is a very common configuration on hybrids. You should have no problem with this.


New wheel. Does it need that little rubber lining between it and the tube? I recently replaced my rear wheel (hooray for figuring out how to remove the cassette). Now I am about to put the old tube in the new wheel. I noticed the new wheel doesn't have any rubber lining to protect the tube from the metal as my old, now broken, wheel did.

Is this an important barrier?

Yes, you will need a rim tape to protect your inner tube from the spoke holes or the spokes in your rim. There are a few exceptions we come to later.

The rim is the outer part of your wheel. Along its or circumference run two flanges to hold the tyre in place. Between the flanges is the rim bed. A rim tape usually needs to be in this bed. Thus can be a glued cloth tape, a strong adhesive tape, a strong elastic tape, or a rubber strip.

Often the rim profile consists of a chamber. It's one end is the rim bed and the other the inner circumference of the rim. The latter has drilled holes for spokes and nipples. The former has wider holes to access the spokes.

Purpose of the rim tape is to prevent the inner tube from expanding into these holes. The rim tape has to be quite strong to prevent this under pressure.

The tape should also cover the whole width of the rim bed. This keeps it from sliding.

If the inner tube expands into the holes it may burst. Either for being over-strained or by rubbing at a burr from drilling.

Some rims have only one chamber. This was especially  common in the days of steel rims. Here the inner tube may be protected by a soft strip of rubber from chafing at nipples.

If a rim has no spoke holes you do not require rim tape to cover the holes. However, it provides an insulating layer to protect the inner tube from heat coming from the brake track. There are plugs available to cover holes, where the same may apply.

Another exception are tubular tyres that are glued to the rim. But these are only found in sophisticated race bikes.


Can the tire type and profile significantly affect balance? I have been riding the same road bike, a Fuji Espree, for a few years and am very used to it: I used to be able to ride it without hands on the handle bar very easily, take 90º turns in city streets because it is well balanced and responds in a predictable way.

I recently changed the old Strada-K Forte tires to new Continental Ride Tour Extra which have a more square profile, deeper grooves.

Since then the balance of the bike has felt off: As soon as I remove my hands from the handle bar, the bike starts steering to the right and even with my hands on it, turning feels harder.
 I'd like to find new tires that won't have that same effect but am not sure what feature is  causing this? My intuition is that the more square profile is causing, do you think that is the case?

I did the exact same thing a long time ago. I wonder what width tyres you used?

Basically, I had a touring bike which I used for "rough" touring, and used the 38c version of this tyre.

It was fine at lower pressures in rough roads.

I then bought a set of 25c versions for a winter road bike. Horrible! These, tyres are not designed for smooth roads and high pressures. If someone doesn't understand this problem, basically, the tyre has no smooth corning edge. None.

Just replace the tyre for something more friendly.

We can recommend tyres for specific scenarios, but you haven't mentioned the type of riding or your preferance in setup.


Adjust Nuvinci nfinity gears After the latest service, my manual Nuvinci nfinity is set to higher gear than before and I want it lowered again. Surfing the web I find nothing like "turn this knob to adjust gear".

The closest I find is installing and replacing it. There are two knobs, by the handle where I would suspect to find them, that might do the trick but they are not explicitly mentioned for after adjustment so I suspect they are only for tensioning the cable housing properly.

Or is it unadjustable? Like when the end stops are set, it goes from 0% (lowest) to 100% (highest) and what has happened is that the end stops are not properly adjusted?
This would imply that the 0-100% gear at the rear is controlled by the 90% travel at the handle and one has to choose whether to have gears 0-90%, 5-95% or 10-100%.

(yes, I can ask the service person to do it but would prefer to do it myself.
yes, I can ask the service person to teach me. but what would be the fun in that?)

So you are saying that the range of ratios available seems to have changed after servicing, so the lowest ratio available is higher than you want it it be?

I think you may be on the right track with the cable adjustment. The cable may be mis-adjusted so the hub is not at it's lowest ratio when the twist grip is at it's low limit position.

Loosening one cable tensioner and tightening the other should shift the relative position of the twist grip and hub mechanism. Keep track of how many turns you apply so you can get back to where you were if you find you are adjusting it the wrong way.

Link to service manual for the hub: https://www.gazelle.nl/media/gene-cms/h/a/handleiding_nuvinci_nfinity_1.pdf


what's the reason for different front and rear tire sizes on a XC MTB? i just received my Moots Mooto X RSL, which i had previously ordered--it's a titanium 29" hardtail, spec'd for XC racing (eg, an upright geometry w/ 100 mm travel on ff, fairly high head angle & seat angle)

Moots (AFAIK) only builds to-order but i know next to nothing about mtb wheels and tires so i deferred to their default spec for both

i just picked up the next bike from the dealer yesterday and the front has a 2.4" wheel; the rear a 2.2"

is this common on mtb builds? Or at least for mtb XC racing builds?

what is the reasoning behind this practice (i assume the wider wheel in front is critical)?

Yes, it is common on mountain bikes to have a wider front tire.  This is to avoid "washing out" in corners.  Plus the extra air volume provides more cushion and increased comfort for your hands (even if you have suspension).


Any tips for aligning fenders? I recently bought a used trekking bike (Focus) to commute to work in Berlin.

It's a great bike, and now that the weather is a little wetter I'm finding that the fenders it came with aren't quite covering the wheels like I would like. About every two weeks they come out of alignment and I have to adjust the screws/bend the stays to get it to cover the wheel again.

Any tips for getting them to stay put? I've adjusted them three times now and it's getting old.

EDIT: I'm not sure the exact brand/model but the rear has 1/2 diameter coverage and the front has about 1/3 diameter coverage.

Material: black plastic

Attachment system: like these:

Or these Planet Bike ones:

I think the first step would be to work out what is causing them to fall out of alignment. Possibilities include:

Vibration when riding causing fitting screws to loosen or parts to rotate
Leaning your bike against something when parked
Someone leaning their bike against yours or tampering with them

In case 1, you can remove the screws and refit them with some threadlocker (a weak glue that keeps machine screws/nuts in place, usually blue in bike applications).

In cases 2 and 3, the stays may be getting bent or fastenings rotated, in which case all you can do it be careful how you park the bike and where you leave it.


Wheel rigidity, is it noticeable and should I care about it? I have a friend who shopped for Aero wheels recently and I heard a lot of talk about how this wheel was more rigid than that wheel and so on.

While I understand that a more rigid wheel should have less loss of energy, can it really be felt? I have entry level wheels and I don't feel any "softness". Is the rigidity of a wheel something that makes a difference only when you're a racer and want to shave off a few tenths of seconds?

(I guess it can be something important for heavily loaded touring bikes, but I'm more interested in "racing" road bikes.)

For the average rider the answer to 'should I care?' is probably not.  If you are racing a lot of time trials then it's possible that it will make a difference.

Some of the primary benefits of a spoked-pneumatic wheel are traction and shock absorption. There is a trade off between increased rigidity (as well as higher air pressure) and both of those benefits.

So, a high rigidity wheel may increase energy transfer, and decrease rolling resistance. At the same time the harsher ride is going to increase fatigue, and the added vibration over anything but the smoothest surfaces will result in a decrease in traction.  Overall for the typical rider it's probably a wash.

It's largely the same story for the Aero benefits as well.  Unless you are primarily concerned about going fast in solo efforts the benefit would be minimal.


Shimano 105 10 and 11 speed compatibility Currently I have on my bike the Shimano 105 system (2 years old) with 10 speed cassette. Currently I am buying a new wheelset (Fulcrum Racing zero) made for Shimano 11 cassette. I was told that I can use my 10 speed cassette but I was planing to upgrade to 11 speed cassette in the future. Is the Shimano 11 speed cassette that comes with the latest Shimano 105 compatible with older 105 systems?

I apologize in advance if I don't make myself too clear.

Thanks for any help

If you want to go from Shimano 10 speed road to 11 speed road, you'll need a new cassette, new shifters, a new chain and a new rear derailleur, since the cable pull ratios have changed (again). Zinn also notes that 10 speed FD might not shift as nicely as 10 speed FD with the 11 speed shifters, so may as well throw one of those in.

So, in the drive train, essentially all you'd be wanting to keep is the crank if you want to go from Shimano 10 speed road to Shimano 11 speed road.


Front axle cone replacement - sizing So I am trying to replace my pitted front axle cones, but struggling to find the parts of the right size.

My axle diameter is 9.4mm on the thread and 8.8mm on the smooth part, and respectively the cone inner diameter is 8.8mm. I have tried a 9mm cone I've got but it predictably doesn't fit.

3/8" axle standard seems close enough - but they seem to be mostly back axles which is a bit concerning. Another problem is that 3/8" cones are all supposed to go with 7x1/4" bearings, while my bearings are 4.7mm (3/16") and there were 10 of them on each side, so I am skeptical.

Would 3/8" cones and/or axle be a good fit for me? If I go with 3/8" cones, which bearings I would need to use, 3/16" or 1/4"? Would it damage the hub if the bearings are not the same size as before?

The length of my old cones (12.5mm) and their outer diameter (15mm) also don't appear to be common. I suspect it must be Shimano CN-R088, but the only UK shop where I can find it only has 1 in stock (and for £10!) If I go with shorter cones which seem to be more common (like the 9mm one on the picture linked above), would it make any critical difference?

Thank you.

9.4mm major diameter means you have a 3/8" axle, which is sometimes even called 9.5mm. The thread on it should be 3/8x26tpi, which again is sometimes called 9.5mm x 26tpi.

All Shimano hubs have the Shimano name and a Shimano-esque part number on them, which for normal front hubs (non-generator etc) will start with "HB-". Shimano doesn't do rebrands. Also all Shimano threaded axle hubs use metric axle threads unless there's a prevailing standard otherwise, as in 3/8"x24tpi internally geared hubs, low-end generator hubs for shopping bikes, etc. So from the sound of it, it's not Shimano.

Things I will say straight off:

Some shops specialize in Dahon and might be able to make this very easy for you. If you had access to such a place, that could be a good way of cutting to the chase.
If you insist on matching a replacement yourself there are technical aspects to getting it right that are a little outside the scope of an SE type answer (or at least one I'm willing to write I guess.) There's a second edition copy of Barnett's floating around the internet. I'm not really sure of the legality so I won't link. I believe it was compiled from sample chapters and it's largely outdated at any rate. However, it does have their chapter on replacement cone matching, the principles of which haven't changed. Every other writing on the subject I've ever seen on the subject is overly pithy and misses some aspects.
One of the key steps in replacement cone matching is testing that the ball track is occurring on the new cone in an appropriate spot. Usually this means nestled neatly in the curvature of the cone, not too high or too low. Barnett's covers this in depth. Any good mechanic will do this test when installing a non-factory replacement cone and not make any promises beforehand. The point is that ordering generic replacement cones online is pretty dicey.
If one really wanted to try ordering them online anyway, you need to find a way to match curvatures. What I would probably do is use a scanner to create a good side view profile of the existing cone and overlay it properly scaled in a graphics app with the side view product images of the various Wheels Mfg 3/8"/9.5mm generic front cones (which they call "Taiwan cones" since several of the dominant OEM hub firms are Taiwanese) I'd be looking at as initial candidates to choose from.

To answer your questions:

Cup and cone hubs typically have no real ability to handle different ball sizes or different numbers of balls, the exception to the latter being most hubs can either have loose balls or retainers with the same size but a lesser number of balls. You need a  front cone. All generic replacement front cones are for 3/16" balls.
The color of the axle is irrelevant. Some have a black oxide finish and some have different kinds of raw or polished finishes. Well kept axles have grease on them and good chromoly ones are very corrosion resistant anyway, so it doesn't really matter.
3/8" axles are one of the sizes where the same size axle is used on front and rear hubs in some applications. So it's not true that 3/8" cones are categorically supposed to go with 7x1/4" balls. 7x1/4" would typically imply a rear hub with a bearing retainer, and in such a hub 9 1/4" balls would typically work without a retainer. You need a front 3/8" cone, which basically all are going to be sized to work with ten 3/16" balls. One of the confusing things about this may be that the metric sized axle standards, which depending on where you look have become more common, use different diameter axles front and rear.

The practical thing to do is one of two things:

Read the Barnett's chapter, then find a shop that has the full range of Wheels Mfg 3/8" front cones and take what you have to go try to find a match. The Barnett's chapter will get into the sealing and length matching considerations, as well as how to transplant pressed seals etc. Wheels Mfg used to make a 3/8" Taiwan Cone kit that I believe is no longer available in kit form, but a lot of shops still have it, and the cones that it came with are all still available.
Fix your existing cones by grinding them with a drill and sandpaper. I've come to have a high regard for this approach since it can usually be made to work acceptably unless the cone is devastated, and replacement cones can be harder to obtain than they used to be. There are questions here about this approach.


Is it possible to use a MTB with rear Boost hub with a Tacx E Blue Twist T2675 E trainer? Greeting,
I want to buy a Tacx E Blue Twist T2675 E ( or any entry to medium home trainer from Tacx ) but I am not sure if it fits with my Rear Syntace X-12 - M12 12x148 Thread Pitch 1.0 Boost E-thru axle system.
I searched a lot the internet but I still couldn't find a good answer. I used this link to search for a Trainer Axle:
https://tacx.com/product/e-thru-trainer-axle/
I find that model T1711 which is for 142x12 would probably fit my requirements?
For modifying Tacx support I found this video

My frame is a MTB 4XL Promaxx 29er from Maxx.de This is the frame details:
My only uncertainty is: Will T1711 be able to hold my bike? or should I make a home-made Axle like in this video?

Also, I am ~130kg naked. Will Tacx hold me and my bike?

I think it's likelier than not that the one you link to won't work with boost.
Boost/148 isn't listed in what it's compatible with. If it was made with 142 in mind it's not likely to work by coincidence, because of trainer thru-axles that are adaptable to different spacings, they do it by swapping spacers around on an axle that's long enough to accommodate whatever. I'd be suspicious of that one being long enough. And, playing games with barely sufficient thread engagement is the main way for the whole thing to go wrong.
Get a Kinetic Traxle Fine T-2100. I've yet to see one not go into whatever trainer. Remember that no matter what you do, the deal with X12 is you must have the conical interface of the frame mated with an appropriate conical washer of some sort, or you'll ruin your frame. The above Traxle has one.


Would a hard tail 29er be a good starter bike for road and light trails? I can't really figure out what kind of bike I should be getting as a "loaner" bike. I have plenty of friends who want to go for a ride but have no bike, and ever since my last loaner got "borrowed" 2 years ago by a friend after the ride, I've been riding solo :(

I have a road bike and a full suspension mountain bike. I do light to medium trails half the time I'm riding, but I cover double those miles on when I'm on the road.

I want a bike that can be a catch-all for friends to join me. Previously I had a hard tail Specialized of some sort with not knobby tires on it that I left between 50-80 PSI. I also never had had a 29er before, and if I'm going to get another bike, I may as well have use for it too. My full suspension is overkill for the local rail trail.

Chances are though, I'll end up on a few good 20-50 mile road bikes with these friends, and I don't want to make them hate the sport due to having the totally wrong bike.

Hoping to get some feedback on how good or bad of an idea this may be! I'm eyeing a used Specialized Fate that's priced relatively well on Craigslist. (But there's a hundred other 29er hard tails out there!)

Short answer yes, a hard tail 29 would be a good fit for what you have described. And it sounds like you already have a fun FS bike and a road bike so it only makes sense. The equation N + 1 comes to mind, where N is the number of bikes you currently own.

29ers roll like nobody's business, they don't accelerate like a smaller tire but the roll over is awesome. For longer 20-50 mile rides a hard tail would not hold you back either especially if your using a fork with speed lock out and smooth tires to reduce spent energy. It won't keep up like a road bike but it won't be completely unbearable either. But a road bike taken on a trail could get interesting quick for an amateur rider.

Sounds to me like you know what you want and have narrowed it down pretty good on your own. I say go for it though.


What needs to be considered when building a winter bike? I have been thinking about making the ultimate winter bike.  Here are some of the things that I have been thinking about.  What else would you think about when building a good winter bike.
I am specifically building this bike for Ottawa, Ontario, Canada.  The average January temperature is -10°C (12 °F) but it can get as cold as −30 °C (−22 °F).  I am interested in making a bike that will ride well in both urban and more rural areas.  It should be able to handle snow and ice.
Frame

Road frames generally have less clearance for wide tires, mud guards etc.
Even when the roads are mostly clear in the winter I often encounter snow filled streets and icy patches.  I am leaning towards a mountain frame because I think that it would be better suited to this kind of semi-technical riding.
I have never used drop bars in the winter before I really liked having a long handle bar.  I found that this really helped to balance on slippery roads.  Seems like if you want drop bars it is best to start with a road frame because adding drop bars looks like a pain.
Corrosion -  An aluminum frame will hold up better than a steel frame in the winter.  I think that the salt will do a number on steel, aluminum should hold up better.

Suspension
Last winter I decided that I want to get a new fork this winter without suspension.  In the summer I feel totally comfortable jumping off ledges on my bike.  In the winter I would not want to jump off anything that required suspension because in winter it is too hard to guess what the traction will be like when landing.  I also found that my suspension froze so even if I had wanted it it would not have helped.
Tires

Studs help grip on ice but will not help in snowy weather.
Wide tires help to float the rider on top of the snow.  If you want to have really wide tires you need to get wider rims.  You can find rims up to 44m wide.

Brakes
I love my disk brakes.  They are very reliable and I trust them.  I have not used rim brakes in the winter but I know when they get wet they grip less well.
Since I want no suspension and disk brakes it is tricky to find a fork.
Lights
In Ottawa the sun can set as early as 4:30.  To see and be seen serious lights are required.
Mud Guards
Last winter I did not use mud guards.  I found generally everything was frozen so I did not get too wet.  I think after I remove my suspension I may add some.
Conclusion

Aluminum Mountain Frame
Disk Brakes
No Suspension
Studded tires (wide if going in deep snow)

What else would you think about when building a bike for the winter?  I am hoping to get a used frame and used parts when possible and make the studded tires.

Good for you, to think of riding as a year-round activity.

I would choose an older steel frame (Specialized Rockhopper from 1994?). Steel is very durable, and the older frame is less to be worried about with salt. Put a little FrameSaver on the insides, and don't worry about it. (I'm not an expert on these, just a Grant Petersen fanboy).

You really don't want to get stranded in an Ottawa winter. Add some storage, and carry:

a plentiful toolkit, including a multitool, pump, and spare tube.
cash for bus & phone
spare batteries for your light
compact warm items, like a balaclava, gloves, and a wool hat

The trick to rim brakes in the wet is to dry them out before you need them. When you anticipate a need to stop (approaching a driveway or intersection, for example), lightly apply the brakes. After one rotation of the wheels you'll have most of your braking power back. After a second rotation, they'll be in great shape.


Remove lubricant from seat tube and seat post I recently bought a second hand bike. It rides pretty well, the only nuisance I have is that the previous owner has spread some lubricant on the seat post. I am pretty sure of this because I see on the tube a greasy black material which goes all the way to where the tube goes into the frame.

So now when I ride it the saddle gets lower and lower, no matter how I tighten it (at a rate of about 2 cm/100 km).

So far I have tried to clean the post and inside if the seat tube with a paper towel, which became black as I expected.

This is a picture of the part after the cleaning

as you can see it there is already a spacer, and there is no quick release.

What is the best way to remove this lubricant?

A thorough way to do it would be to:

Remove the cranks, bottom bracket and seat post.
Make sure there is a decent hole between the seat tube and bottom bracket shell (might depend on the frame).
Ram rags down the seat tube with a broom handle and extract them via the bottom bracket shell.
Once the bulk of the grease is removed (or pushed to the bottom of the seat tube) soak a rag in degreaser (WD40, white spirit, citrus degreaser etc) and ram it through to remove the last traces.

This would be a bit of a pain though and you might not have the tools or knowledge to remove and refit a BB.

You could instead try tying a strong cord to the rag so that you can ram it down the seat tube then pull it back out. If the cord breaks or slips though you'll be back to removing the BB or you will just have to leave the rag there.

You should also ask why the seat post is slipping, as they shouldn't do so even when greased. Actually, it is normally recommended that you grease seatposts lightly so that they don't seize in place. Could there be something wrong with the seat clamp? Alternatively, seat posts tend to slip when they are slightly too small for the seat tube. It seems annoyingly common for manufacturers not to spec the seat tube diameter properly but it could be that the previous owner replaced the seat post with one that is too narrow?

If you are dealing with a screw-type seat post clamp (as opposed to a quick release) and you are doing it up as tight as you can in an effort to stop it slipping then I would strongly recommend that you carry a spare one with you. I have broken a seat post clamp doing the same thing and it was quite a miserable cycle with no saddle to the nearest bicycle shop 10 miles away.

If you have a quick release seat post clamp my gut feeling is that you could improve your clamping force by moving to a screw-type one. Get one with a large diameter screw if possible but make sure that screw is made of steel! Some use aluminium for the screw which is garbage. Also preferably get one where the screw threads into a steel insert rather than into the aluminium body of the clamp.

Edit: As the commenters have said, carbon frames should not be greased. They use an anti-slip or 'carbon assembly' paste. This paste might help you even if your frame is not carbon; I've never managed to get a straight answer on whether it works for metal-on-metal contact.

Also the double seat post clamp linked by Carel Looks brilliant. I've not seen such a thing before.


Studded tyres on asphalt I'm curious is it possible to make a tyre that will fit perfectly on snowy/icy road. So I found studded tyres.
Now, my question is - Is it possible to make studded tyre that will have good grip on snowy/icy road/sidewalk and use same tyre for dry road/sidewalk?
Reason I want tyre with those specs is because I ride a bike in winter from house to work. Because it's too cold outside, I can't hold with traffic so I ride on sidewalk. Some sidewalks are clear, but on certain parts are ice or "compressed" snow. Without studded tyre it's not possible to brake or change direction.
Where I should put screws in tyre? In middle or at sides of tyre?

You can use good quality ice tires with carbide studs on bare concrete or tarmac, without undue wear on the studs.


Upgrading the crankset - Scott Aspect 960 First of all a big thank you for everybody who can help out with the question!
The bike is Scott Aspect 960: https://www.scott-sports.com/gb/en/product/scott-aspect-960-red-bike
Currently the highest gear ratio is 36/11. I'm looking to upgrade that to go on a more slower cadence on long gravel routes at a higher speed.
Would replacing the front cassette with this one do the job: https://www.bike-discount.de/en/shop/crank-2-3-x-8-speed-409/l-24
The shifter for the crankset has 2 gears listed, but the crankset here has three gears. What are the solutions for upgrading?

More info:  When we need to go with a 2 ring crankset, would this work:
https://bike.shimano.com/en-EU/product/component/shimano/FC-M315-2.html
https://www.modernbike.com/shimano-alivio-m415-42t-7-8-speed-outer-chainring
I'm anyways looking to upgrade the crankset to a Shimano one, so would it fit with this larger chainring?
As I understand, I would need to put on a longer chain then as well?

You have 2 choices: upgrade to a Shimano 2 chainring crank, keep the left shifter, or upgrade to a 3 chainring crank and replace the left shifter with a 3x version.
In both cases the crank must be compatible with '8 speeds'. Sprocket spacing in both the rear cassette and chainrings get progressively narrower as the number of sprockets goes up, and chains get progressively narrower too.
Before you purchase a crank, you need to check that you have clearance between the chainrings and drive-side chainstay. All bike frame have a maximum chainring size they can accommodate. Also check that you can move the front derailleur up slightly to align with the larger rings.
Replacing just the large chainring is not a great idea. Front derailleurs are designed to work with a certain size difference between the chainrings. If you exceed that upshifting will be poor or will not work at all.
Chainring replacement is tricky, there are many ways for rings to be incompatible with cranks. Many lower end cranks do not even have replaceable rings, the rings and spider are a single stamping and riveted together. The crank you linked to has this construction.


Shimano/third-party rotor compatibility with low end hydraulic brakes Shimano say that their lower end hydraulic brakes (e.g., BR-M365) are compatible with 'wide' rotors. See http://productinfo.shimano.com/#/com/2.0?acid=C-461&cid=C-460 for details.

Wide rotors are those numbered below 60, e.g., RT54. Narrow are those higher than 60, e.g., RT66.

The wide rotors (i.e. those below RT60) are made of low-quality metal and claim to be incompatible with metal pads.

What are some third-party, etc. options for getting better quality rotors?

As you mention SM-RT54 and 66 rotors, I will infer you have Deore level calipers. (Deore is not 'low end' IMHO, as the 'cheap A's' (Alivio, Acera and Altus) and almost unmentionable Tourney are below it.)

If you check out the Shimano Product Line docs for Deore you will see that the SM-RT64, SM-RT54, SM-RT66 and SM-RT56 rotors are all compatible with the BR-M6000 and BR-MT500 calipers. The SM-RT64 and SM-RT66 are both metal pad compatible.

Note that the BR-MT500 caliper is not metal pad compatible though, so you should check your caliper compatibility.


What to look for in Riding Suits? I have been using a riding jacket but it is a bit hot during summer over long trips. I like the jacket because it is very simple, only one pocket for a key and it protects in accidents (or so I think).

I have now used a so-called "technical t-shirt" used by footballers and armies as underwear. It moves the moisture out of the skin so my body temperature is more stable even with the jacket. I have replaced my cotton t-shirt under the jacket with it and I feel much better with it. I am unsure why but it works, ideas about such layered bicycling welcome.

I have been considering to buy this suit here but I have no experience with them earlier. What should I look for with this kind of suits? And how do layers work here? Which layer moves the moisture, not to get cold etc?

For the wicking action to work you need to wear something that is relatively taut on the skin. Any common jersey should do the job. I and others have had success with light weight wool jerseys like from ibex.

Generally speaking, cotton is not a good choice for the base layer next to your skin. It will work for a while but as soon as it gets drenched with sweat you'll be miserable.

Layering is key for colder weather. First knee and arm warmers, then a cap under helmet, and shoe covers, then a lightweight jacket or winter training jersey. After that, a "dicky" for your neck and tights over the bibs


Need help with gears and wheel alignment i have an aluminium frame single speed. I wanted to know is it possible to add gears to it (correctly). I saw same model with gears installed but the rear wheel was not in line with front wheel and was moved to a little left to accommodate the 7 speed gear freewheel. Is this something acceptable or a disaster to happen.

The rear spacing on most single speed frames is 120mm. The dropouts usually face backwards and can't take a derailleur very easily. Is your bike like this?
If so, a hub gear may be the best option. You can get a 2, 3, 5 or 8 speed hub gear that fits a 120mm rear end. This will maintain the clean look of a single speed, especially the 2-speed, that needs no extra cables.
If you try derailleur gears, you will need to create a hub setup that has enough space on one side for the sprockets/freewheel. You are unlikely to be able to do better than 5 gears, and mounting the derailleur will be a challenge unless you find an adaptor fit for purpose.


Can you run a standard tyre on a tubeless rim? I have some new tubeless MTB rims and I'd like to avoid buying new tyres for them.  The tyres are reasonably sturdy (Continental Race King Protection - 4 plies / total 240tpi) and I have sealant. As I understand it the sidewalls aren't as tough so you can't run on quite as low pressures as UST tyres but that's OK with me.

Any other potential problems?

I've been waiting until I had enough time to give this a proper answer, because the answer to the question in the title is "it depends" and it's a very important "it depends." It runs the gamut from yes to absolutely not. I want to cover road bike tires here as well, as I don't want folks making the jump from "it's ok for mountain bikes" to "it's ok for road bikes." Cyclocross bikes sit right about in the middle depending on the pressure you like to run

For mountain bikes you can run just about any tire you want on a tubeless rim as long as you use sealant. There are some exceptions, as I covered in my answer here. It's also important to note that when you go tubeless you cannot run the high end of your tires' pressure range anymore. The wider the tire, the more this is true. Most folks have no intention of switching to tubeless and pumping their tires up tight, but then again you'd be surprised.

For cyclocross tires, pretty much everything above holds true, especially the bit above pressure. If you're considering running anything above 50psi you need to get a dedicated tubeless cyclocross tire. It's just not worth the risk otherwise.

For road, the answer is an emphatic, unequivocal no. You cannot run road tires made for tubes on a tubeless setup. Ever. They will blow off the rim, hopefully before you even get them up to pressure, and you will get hurt or killed. You can convert a normal rim to a tubeless setup with a kit, but you cannot run a normal road tire on any tubeless road setup. If you want to know why, keep reading...

The whole reason pneumatic tires work is because they're pushing outward on the wall of the tube or tire. PSI stands for pounds per square inch. I assume everyone already knows that but what some haven't thought about is that the term is pretty literal. For every 1 PSI you pump up your tire the air pressure inside is literally exerting a pound of force per square inch on the inside relative to outside atmospheric pressure. That's why if you're a 150lb rider, bike and all, and you have your tires pumped up to 100psi, you've got a grand total of 1.5 square inches of rubber making contact with the road (there are other circumstances to take into account here like casing and compound, but we wont nitpick material physics here). That also means that you've got enormous amounts of pressure trying to tear your tire off the rim in every direction. The bead on wire (non-folding) and kevlar (folding) beaded tires is ever so slightly stretchy. Not very stretchy, but just enough that neither type of bead will stay seated on the rim under the amount of force which the air inside of a pumped up road tire is exerting outward on the tire. Think about what a tube does when you over-inflate it outside the tire- it expands to a much larger diameter than your wheel. Your tire is doing the same thing on a much smaller scale. It's doing this just enough that a standard bead without a tube in place can climb out of the channel where it sits and over the edge of your rim, causing catastrophic results if you're rolling.

With a tube in place inside a rim, the air pressure pushes against the tube first which in turn pushes against the tire which binds the bead in place against the rim. The interaction between the tube pushing against the tire vs just air pressure pushing against the tire is a little different. The tube helps reinforce the pressure against the bead and lock it in place whereas air pressure alone is not enough to fight against the tire's need to expand in diameter.

So how do tubeless road (and "official" tubeless cyclocross) tires fix this problem? Instead of a kevlar or wire bead- both of which have a little bit of stretch to them- tubeless road tires use a carbon fiber bead which has virtually no stretch to it at all. Since they don't stretch, carbon fiber beads are not susceptible to the pressure inside the tire tearing them off the rim like a standard bead (I'll mention that road tubeless tires typically have a little differently shaped bead as well, but this is more to prevent burping when matched with an official road tubeless rim). This is why you can convert a standard road rim to tubeless but you cannot cannot cannot run a standard road tire on a tubeless setup, official tubeless rim or not.

The same problem described for road tubeless can apply to cyclocross or mountain bike setups if the pressure is high enough. That's why carbon fiber beaded tires are available for cyclocross but you can run a standard cross tire tubeless at lower pressure. For mountain bikes non-elastic beads just aren't necessary because no one in their right mind pumps a mtb tire up that tight to begin with- tubeless or not.


Newbie Question: What do speeds mean on chains? I'm shopping for a new chain, and I noticed some inconsistencies when discussing speeds. Specifically, speeds applied to the cassette refer to how many layer of gears it has (I presume). Speeds, when applied to bikes, refers to the total number of speeds it has with the cassette (or freewheel) multiplied by the chainring on the crankset.

Soooo... what do the speeds listed on a chain refer to (ignoring the compatibility issues -- those are very well documented)?

For example, if I have a cassette with 5 gears and a crankset with 2 gears, do I need a 10 speed chain or a 5 speed chain?

A bike with a 5 cog cassette requires a 3/32" 5 speed chain which has also been referred to as the "10 speed chain". This is different to a modern 10 speed chain though as below.

In rrecent times speeds refer to the number of cogs that make up the rear cassette. Outside of big box stores gearing is generally specified as YxZ. So in a department store you may see a bike advertised as having 21, 24, 27, 20 or 11 speeds whereas in a bike store it would be sold as 3x7, 3x8, 3x9, 2x10 or 1x11 (right up to 1x12 which strangely is currently referred to just as Eagle!)

The reasoning behind specific chains for different speeds is as they have increased the number of gears available on a bike they have maintained the same freehub width over the last 4 iterations. 8, 9, 10 and some 11 speed cassettes all work on the same width hub. This has been achieved by spacing the cogs closer together and producing narrower chains.

There is generally tolerance in a chain to go up/down 1 speed without issue. Ie. an 11 speed chain can be used on a 10 speed cassette.


Does anybody manufacture extra-wide (3E/4E or EEE/EEEE ) wide road or mountain biking shoes? I have mutant-wide feet and it's generally impossible to find comfortable shoes for any occasion. For the most part my only options in life are New Balance. I'm cycling a lot lately and would like to take advantage of cleats. So, does anybody actually manufacture 4E shoes? I'd rather not try stretching them out with mink oil/boiling water/wooden shoe stretchers and the pain from narrow shoes can be pretty excruciating. My google-fu is coming up with a few dozen forum discussions with no real solutions.

Sidi make a wide fitting version of their shoes.

I have a pair of Sidi's and they have been the best fitting, most comfortable shoes I've ever found. From their website:

  Mega sizes are cut with more material throughout, and a larger-volume heelcup. Mega sizes roughly correspond to a EE/EEE width on the Brannock sizing scale.

Possibly still not wide enough for your needs but they're worth checking out.


Clicking sound on handlebar I get a clicking sound every time I go uphill, sometimes I can even feel it. It's coming from somewhere around the handlebar. I keep thinking that my handlebar might be cracking but its just my imagination.

When riding uphill you are putting more force on the bars to counteract the greater force you legs have to exert on the pedals.

What is probably happening is when you exert more force the handlebar or steerer tube is shifting in the stem clamps slightly, causing a creak or click.

Your stem clamp bolts should be tightened to the correct maximum torque. If that does not fix the problem the stem may need dissembling and re-assembling with some grease or assembly compound.


Is it possible to date Shimano components? I have heard that Shimano releases an updated or redesigned component line about every four years. The old technology then passes down to the less expensive product line. If this is true, theoreticaly a newer Ultegra component would be a better buy and possibly of better quality than an older Dura-Ace. So my thought is, can you reliably date a component that has no serial numbers or manufacture date.

All Shimano components have a series number (not serial number) embossed or engraved in the component.  While it is possible that the numbers may be worn off or scratched over on older components, the theory you are working under seems to indicate that you would be looking for newer, lower level components, rather than older higher end stuff.

Check the back of the inside front derailleur plate for a number like FD-6700, for example, (which would indicate current Ultegra).  There is a number on each component, with the first 2 letters indicating the type of component, and the number indicating the series.

For Example:

CN = Chain
ST = Shifter
BR = Brake
FD = Front derailleur
RD = Rear derailleur
HB = Hub
WH = wheel
BL = Brake lever
CR = Chain ring
CS = crank set

The higher the number the higher the component level.  Current 11 speed Dura Ace is 9000 series. Last year's 10 speed Dura Ace was 7900. The series prior was 7800.

For Ultegra, the upcoming, not yet released group for Ultegra will likely be 8000.  The current is 6700 for most components. 6600 was the prior group, and 6500 before that.

If the 3rd number is a 5, as in 6650, (ususally only noted on the crank) then the group came with a compact crank.

If the 4th number is not zero, it is either a revision, in the case of CN-6501 or 6502, or designed for a triple crank.  This will be noted on all parts, as shifters and derailleurs also must change for a triple geared crank, in most cases.

If the 3rd number is a 7, i.e. FD-6770 the part was designed for electronic shifting.  This will be on derailleurs, batteries, wiring, and shift levers.
If you find a number on any single component, it can be used to date the whole group set.

I hope that is useful.


lacing Alfine wheel, trailing spokes inside or outside hub flange I am about to lace an Alvine hub wheel. Reading Sheldon Browns article there is a suggestion that the trailing, and so key, spokes might be better laced the opposite of what would be done for a deraillieur wheel. Meaning that the trailing spokes would go on the outside of the flange of the hub, thus the flat end of the spoke is on the inside of the flange.
Is this advisable and correct or does it not really matter? Or have I misunderstood completely.

Thanks for reading.

If I remember correctly Shimano recommends lacing with trailing spoke heads in (flat part out) for rear drive-side whereas Sheldon Brown recommends the opposite, so take the reasoning that sounds best to you and run with it. Ultimately it probably doesn't matter much, especially if your chain doesn't fall off to the inside which it shouldn't if everything is in proper adjustment. I just looked at two sets of wheels that I have built which are nearly identical. On the older set I have drive-side trailing spokes with heads facing out, on the other set they are facing in. I have no recollection of why I made the change. I do not notice a difference and I haven't had problems out of either set. If I were going to build another set right now I would probably do trailing heads facing out, but as Sheldon Brown pointed out:

  Note: This is not an important issue! There is a sizable minority of good wheelbuilders who prefer to go the other way around, and good wheels can be built either way.


Is this bike suitable for a male Is this bike suitable for men?

The Older Paradigm of Women's Specific Bikes
Argenti and Kaz both are correct, but let's dive a bit deeper into women's specific design (WSD). Their answers allude to an old paradigm of WSD. It appears to be based on anthropometric measurements collected by the US Army around the 1950s. Here is a relevant 2017 interview with Stephanie Kaplan, a product manager with Specialized. These data showed that the average woman had relatively longer legs and a shorter torso than an average man of the same height.
Operating from those data, manufacturers would typically make a WSD bike that had a relatively shorter top tube than a men's bike in the same size. Obviously, they would also offer smaller sizes (the average woman is shorter than the average man, which is probably beyond debate), women's specific saddles, and narrower handlebars.
Compare Boardman's current MTX 8.6 women's bike to the men's version of the same bike, you can see this paradigm in operation. A frame's reach is basically how long it is, and its stack is basically how tall it is. I'm comparing two frames whose absolute size is relatively similar below.
Medium women's MTX8.6:
Recommended rider height 157-170cm
Stack 615mm
Reach 387mm
Small men's MTX 8.6:
Recommended rider height 160-172cm
Stack 602mm
Reach 391mm
Basically, compared to the equivalent men's frame, the women's frame has a more upright position, and it's slightly shorter.
Some Companies are Challenging the Old Paradigm
Some manufacturers, like Trek and Specialized, initially embraced the older WSD paradigm by offering different frames. More recently, at least these two manufacturers have gone more to a modified unisex approach. They offer the same frame measurements to men and women. However, they make sure to offer smaller sizes, and they alter the contact points for the bikes actually sold to women.
In the interview I linked, Kaplan discussed the data that Specialized obtained from their Retül service. Retül was an independent bike fitting company that Specialized bought, so Specialized now have current and accurate measurements on riders. Kaplan said that in that data, they didn't see any justification for offering different geometries in the same frame size. Thus, they feel able to accommodate female riders with the same basic frame. However, given a frame size, the saddles are different, and women may have narrower handlebars. Additionally, they expanded their size range. For example, I am 5'5". I recall that when I first bought a road bike in 2001, I had a 48cm Specialized Allez, and that was the smallest frame offered. Current road bikes now have a 44cm size.
Bonnie Tu, who runs Liv (a sister company of Giant Bicycles that only offers women's bikes), has said that a unisex approach basically means that the bikes are made for men. She is clearly correct in at least some instances; my current gravel bike is a small Parlee Chebacco, and Parlee only offers 4 sizes, small through extra large. Shorter female riders are likely to have fit problems on the small frame. Whatever good things I have to say about the Parlee, they clearly didn't consider women's sizing at all. The approach taken by Trek and Specialized is far more thoughtful.
Not all manufacturers are going the unisex route! This 2017 review of Canyon's women's CF SLX bike outlined Canyon's approach:

Canyon’s online ordering system collects body dimension data from all its customers, including height, weight, and leg and arm length. While this information helped people identify which frame size to purchase, the data — now over 60,000 entries strong — also gave the engineers at Canyon a clear picture of the biometric and anatomical make-up and requirements of its customers.
That data not only showed some fundamental differences in the male and female dimensions, but also the exact nature of those differences. Most notably, Canyon found that, contrary to popular belief, women’s legs are only marginally longer than men’s legs for a given height. However, their arms are consistently shorter (by 2cm on average) for a given torso length. According to Canyon’s data, women also tend to be shorter and lighter, and they have greater pelvic flexibility.
Taking all of this data into account, Canyon designed the new WMN frame geometries with slightly higher stacks and shorter reaches compared to the unisex frames. The WMN frames are also lighter than the unisex versions for a given size, feature more aerodynamic profiles, and the size range now extends down to 3XS to cover rider heights as low as 152cm (5’ 0″).

Which approach to bike geometry is correct? That may be impossible to answer without getting anthropometric measurements from a true random sample of the population. One criticism of the older measurements is that they are much less ethnically diverse than the global market, and they may not have been taken consistently. I believe Kaplan argued in the podcast I linked or elsewhere that the Retül measurements are much more accurate than the US Army ones were. However, the people who get fits from Retül are different from the people who shop online for Canyon bikes, and both are different from the general population. Their data could be biased - although if you believe the US Army data are correct, it is hard to come up with a scenario explaining how Specialized's sampling scheme would bias their data that way.
We Want All Riders to Have Access to Bikes That Meet Their Needs
There is another dimension to the question "is this bike suitable": does this bike have the capability to meet my needs? I think this doesn't apply to your situation, but the old WSD paradigm was to "shrink and pink" the bikes, and also to down-spec them.
It's possible that some spec changes are warranted. Some of those issues are discussed here and here. For example, the Specialized Allez and Dolce are entry level road bikes, but the Dolce is a women's frame and the Allez is unisex. The Dolce has less aggressive geometry (more upright, steers slower) and has more vibration damping features than the Allez. This may make sense for entry-level female vs male riders. (Alternatively, it may be what the male-dominated bike industry thinks women want, and they may be wrong.) Canyon, in the quote above, said that its women's frames use lighter (but more aerodynamic) tubing than same-size men's bikes. I am guessing their assumption is that on average and controlling for height, women will put out less power than men. They don't need heavier tubing; they won't benefit from the additional lateral stiffness, and they will benefit from greater vertical compliance. (Note: frame stiffness may not matter that much for any rider, but this is another story.) In addition, Bonnie Tu has emphasized that

It takes a female cyclist to understand what makes a ride painful or uncomfortable, and what will make a woman feel more relaxed. It needs to come from a personal experience, so it has got to be designed by women.

She might be wrong, but the bike industry has historically failed to disprove her.
Aside from warranted spec changes, we don't want women's bikes to be crummier versions of the stuff available to men. In a podcast interview with Velonews, Berne Broudy discussed how she and multiple pro or competitive female athletes she knew would often ask for the men's bikes, because those had the component specifications they wanted. As another example, I recall than the 2010 Specialized S-Works women's shoes had a lower stiffness rating than the men's S-Works shoes - I know this because I have a pair of the women's shoes due to fit reasons (discussed below).
More subjectively, Broudy discussed on the podcast that the early marketing and overall messaging for women's bikes and products was ultimately condescending and sexist. This impeded take up as well. Further, Broudy pointed out in the podcast and the excellent companion article that some products originally designed for women were adopted by men side as well. She pointed towards the cut out saddles pioneered by Georgena Terry and the later Specialized Power Mimic saddle. Thus, it is possible to make at least some unisex products that actually serve all genders well.
That Frame Could Potentially Suit a Male Rider, and it Might Suit You
Back to the original question! Does the frame fit you? You can move the stem lower on the steerer tube if the stock position is too high for you.
Its components aside from the saddle may have been identical to the men's version. Hence, color aside, this bike is potentially suitable for some men, perhaps even many men. It will not be suitable for all men. We can't say for sure if it's suitable for you personally. That is what matters. If it fits (or it can be adjusted to fit) and the components meet your needs, then you could consider it. I will assume that Boardman specced a women's saddle, and it's more likely you'd want to change that (but it's not guaranteed). If so, I suspect it will be wider than the average men's saddle. I'm not familiar with front suspensions, but I guess it's possible that the suspension they chose was selected for the average weight of a female rider in the height range it was designed for. If you're heavier than this, it's possible you might find it's too compliant for you (i.e. your weight pushes it down more than it was designed for). This is speculation on my part.
Getting into the social aspects of WSD bikes is going to be primarily opinion based, and thus not really suitable for discussion on Stack Exchange. I will say that some fairly knowledgeable cyclists will know you're on a WSD frame. I think that most of these people would not judge you for it. I think that those who do judge you are doing humanity a disservice. The average person on the street probably won't know. The average rider I met never made a remark about my ladies shoes. The distinction between men's and women's paint schemes may be getting less distinct. Besides, pastels may well come into fashion for men. You could be setting a trend. (My shoes were all white and they matched my bike.)
On a Personal Note
As a side note, I'm a 5' 5" male cyclist. My bike is white with pink accents. I have a pretty long torso. I'm 1 inch taller than my wife, but my hips are actually a bit lower than hers. I have actually worn one pair of women's specific Specialized shoes because the last was identical but for the tighter heel cup, which fit my feet.
So, while I'm proportioned more like a stereotypical male under the old WSD paradigm, issues of fit definitely resonate with me. I can typically ride the smallest unisex bikes of (I think) all major bike manufacturers, although their seat tube angles are a bit more slack than I prefer. This typically causes some toe overlap, which isn't relevant on road bikes, but may sometimes be an issue off road. Also, a lot of shoes don't fit my feet well!!


Identify control on left-side of Sun Recumbent Trike model EZ3 handlebar I own the Trike model listed above, I bought this Trike about 10 years ago, and I'm starting riding again but since the manuals are not very users friendly, I need to know the purpose of the 3 position knob for on the left handle?

Based on the specs at https://bicycleman.com/sun-ez-3-ez-3-ltd-recumbent-trike/ your trike has a triple front chainring and a 7 speed cassette in the rear.

The three-position control will be to adjust the front chainring while riding, so the bigger one is "harder" and the smaller one is "easier"  Which one you choose depends on the terrain, but the middle or bigger chainrings are common, with the middle and smaller ones used on slower climbs.

Your right-side handlebar will have a 7 position shifter for the cassette at the rear.  This is more of a fine control, whereas the chainrings are a coarse control.

In automotive terms, the rear cassette is a gearbox, and the chainrings are a transfer case letting you select between high-box, middle-box, and low-box.  If manual truck transmissions are confusing, just ignore this paragraph :)

Aside - your bike may have "parking brakes" too, which is relatively unusual for a bicycle.  Pressing the button on the brake levers will hold them in place, stopping the trike from rolling away.  You wouldn't want to press them while riding.


Shimano M355 part broken Was riding my bike over a jump when i lost control and bailed. This led to a tiny part on top of the brake lever to snap and come off. Cant find any details on the part and its not on any diagrams or part lists. It looks like a little black, plastic screw with three bits coming down from it. Its the Shimano M355 Hydraulic MTB Disc Brakes. Picture attached, hope someone can help.
Thanks,
Ben

I know what that is. It’s the pivot for the brake lever, and Shimano does not sell extras. Your options are:

Buy a new brake system or lever (depending on which is cheaper. Used is fine as well. All Shimano MTB brakes are inter-compatible.)
Go to your LBS and ask if they have a lever you can cannibalize. A friend of mine broke the exact same part and our LBS happened to have a spare lever they keep around for spare parts.

Be careful while fiddling with that 2mm hex fitting. It’s easy to strip out, and fixing that will definitely mean a new lever.


Reason for different hex screw sizes Recently I've installed a front derailleur and while doing it used nearly all hex screwdrivers from my multitool. For example, on the left hand of the handlebars I have a brake, a shifter and a fork lockout. To unscrew them I have to use 3 different screwdrivers (the one on the grip is the same as on the lockout). Needless to say that to put a cable on the frame I have to use different ones.

What is the reason for that (except for the multitool manufacturers conspiracy)?

Generally, bigger sizes of screw heads allow higher torque to be applied to them. This is also often expressed in lengths of wrenches used for them in workshops: typically a 3 mm L-shaped hex key is shorter than a 4 mm one, which in turn is shorter than 5 and 6 mm ones etc. Multitools are exceptions because of size constraints of tool bodies; it is typical to see a 8 mm hex head on a multitool with inadequately short leverage.

An unnecessarily big screw would also mean more "dead" space is needed in the parts such screw connect. These parts are collars of brake levers, derailleur shifters, grips etc. "hugging" the handlebar's tube. Collars interfere with each other, preventing you from finding the most comfortable position of e.g. brake lever. By the way, this is why top-level brake/shifter combinations basically use a single collar and are connected together (Ispec, MatchMaker etc.)

Bigger torque is needed to counteract bigger force × leverage applied to a specific component. For handlebar components, forces are produced by user's hands/palms and have the same order of magnitude regardless of which component is being "touched". The applied force being fixed, it is the leverage (in centimeters) that should decide achievable range of user-supplied torque and thus required screw-supplied counter-torque.

Lock-on handlebar grips tend to have the smallest screws (1.5 - 2.5 mm) because grips sit very tight to the handlebar. Leverage applied to them is defined by their thickness and is an order of 1 cm.
Shifters typically have relatively large paddles sitting far away from the handlebar's axle, let's say 3 cm away. A 4 mm screw would seem to be adequate to hold them securely.
Brake levers have dimensions and leverage comparable to shifters'. Thus, screws of the same size should suffice for them. However, brakes are more critical to rider's safety, and them rotating around the handlebar is even less desirable. As an additional precaution, they are installed with higher torque and thus bigger screws (5 mm).
Fork lockout control is smaller than both shifters and brake levers, but bigger than grips, so I would say it may have a screw somewhere in-between (2.5 - 3 mm).


Are bikes with sloping top tubes lighter than bikes with horizontal top tubes? For many years bicycles nearly universally had horizontal top tubes, but that has changed: now most bicycles have "compact" geometry, with top tubes that slope downwards from front to back. The question "What is the difference between a horizontal top tube and a sloped one?" generated a great discussion of the pros and cons of "compact" frames versus frames with horizontal top tubes.  I have shamelessly stolen the pictures from that question.
Here's a bike with a horizontal top tube:

And here's a bike with a "compact" frame with a sloping top tube:

Answers to the other question pointed out that manufacturers don't need as many sizes with compact frames compared to frames with horizontal top tubes.  I know that fewer models of a frame is an enormous advantage for manufacturers, distributors, and retailers, because fewer SKUs require less frames to be stocked, which brings costs down and better satisfies customers.  That alone is surely strong motivation for manufacturers to adopt the compact geometry.
But I'm very curious to know if bikes with compact frames are actually lighter.  Answers to the other question disagree on this point, which is why I'm asking a new question.  Definitive proof would be nice, although that is surely hard to find.  If compact frames were actually heavier or less stiff, other things being equal, then I assume that manufacturers would be motivated to tell white lies that bikes with compact frames are lighter and stiffer; manufacturers would surely prefer that people think design changes were intended to benefit riders, rather than being purely for business reasons.
So are bikes with sloping top tubes lighter than bikes with horizontal top tubes?

Conclusion
My goal in asking this question has been to determine why manufacturers really changed to compact geometry from the older geometry with horizontal top tubes.  At least one manufacturer claims that the smaller frame triangles make the frame lighter and stiffer, and makes it easier to fit riders of all sizes.  I think the answer to this question is correct, and that compact frame bikes are not actually substantially lighter than bikes with horizontal top tubes.  I doubt that they're stiffer either, because the frame may be slightly stiffer, but the much longer and therefore bendier seatpost will probably negate that advantage.
Comments to the answer also point out that if the rider wants higher handlebars with a modern threadless stem, then the top tube has to slope for stand-over clearance.  That seems to me to be a mere style issue that could be solved without sloping the top tube, by making the front tube or the steerer a bit longer.  I believe the first picture in the question proves that point: the bicycle has high handlebars, a modern threadless stem, and a horizontal top tube.
That leaves what I believe is the real reason that manufacturers have switched to compact geometry: they don't need to stock nearly as many sizes.  This is an enormous business advantage, because manufacturers, distributors, and retailers don't need to stock as many SKUs.  Hopefully some of the cost savings result in lower prices for consumers.
To sum up, I don't think a bike with compact geometry is a substantially better bike than one with a horizontal top tube, other things being equal, but the bike with compact geometry was slightly cheaper to warehouse and distribute.

So are bikes with sloping top tubes lighter than bikes with horizontal top tubes?

No.
The frame may be lighter but the total bicycle ain't. The larger bending moment at the location where the seatpost enters the frame must be supported, and it means the seatpost requires more material besides needing to be longer. Even if the seatpost is not made more sturdy (which would mean you're not comparing apples to apples anymore, as you can't just increase the seatpost length and have an equally durable seatpost), a given length of the seatpost would weigh more than the same length of the seat tube.
The reason for sloping top tubes is something entirely different. Just look at the relative saddle and handlebar heights of the two bikes. The horizontal top tube frame has low handlebars, whereas the sloping top tube frame has high handlebars.
Now, you can have high handlebars on a horizontal top tube frame you can stand over, but it would require lots of spacers around the fork steerer tube, or alternatively a high-rise stem. Many people consider the look of either of these solutions ugly.
I have a Surly Long Haul Trucker I built myself. It has a 17 degree stem flipped down, so the stem is horizontal in addition to the top tube. It indeed requires a very very large number of spacers around the fork steerer tube. This is despite the fact that the height of the top tube above the ground is such that I can barely stand over the frame.
If you want to have handlebars at the same height as the saddle, either you require a sloping top tube, a lot of spacers or a high-rise stem.
This of course doesn't affect those of us who prefer a low racing style handlebar height.
So, the reason for sloping top tubes is most likely the fact that we have nowadays threadless headsets (aheadsets) and the stems that clamp around the fork steerer tube. When horizontal top tube bikes were the norm, we had quill stems that don't require spacers.


I need a new bike derailleur, which one? I have a fairly old Specialized Hardrock Sport.
I want to get new derailleurs. Is there a specific one I should get. I'm not sure the one now is the original.

It looks like Specialized built bikes with that name from 1993-2010. A lot changed over that time.
In the last year the bike was produced, it had a triple crankset (and presumably before). Triple chainrings are less popular these days, so your choices for a front derailleur will be limited.
For the rear derailleur, you'll need to find something compatible with A) the shifter, and B) the number of sprockets. This will come down to the derailleur's "cable pull ratio," and without knowing more about your specific bike, it's not possible to make a recommendation. Even with that information, it may take some archeology to dig up the right answer.
What is the specific problem you hope to solve by getting new derailleurs? There may be a different solution.


How to make a cargo trailer? This page is for a general answer and it consists of at least two main parts: personal experience and technical part. The technical parts are perhaps the two hardest parts.

Has anyone attempted to make a cargo trailer for their bike? How did you do it?  How has it worked? How long did it take? Would you do it again?

Technical parts with their own separate questions

How can you make a trailer hitch between a bike and trailer?
How can you attach/mount a wheel onto a trailer?

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).


What are the most significant factors affecting downhill cruising speed? When I'm riding with my friend, I notice that he rolls down hills significantly faster than me. We can be riding next to each other, both in a similar aerodynamic position, but if we both coast he pulls away from me surprisingly quickly.

I'm a fair bit taller than him and probably weigh a little more (but only a few kilograms/pounds). Our bikes are similar. We both tuck into a similar position.

Apart from our size/shape, the main difference I can see are wheels. I have Campagnolo Khamsin and he has a set of American Classics that he purchased after he got the bike and spent about $800 on. They have a much deeper V than my wheels. My main theory is that the wheels are what's making the difference, possibly with aerodynamics and also better rolling resistance in the hubs, but I'm not sure how to confirm or deny this.

The following forces are acting on your bike as you roll downhill (in more or less decreasing order):

Gravity

The force of gravity is proportional to mass. If two riders have the same aerodynamic profile, the heavier rider will descend with a higher maximum speed.
This is easily seen in the formula for terminal velocity. The intuitive explanation is that the two will experience the same force due to drag, but the heavier rider will have a higher force due to gravity.

As you are heavier than your friend, gravity can't explain why he is faster.

Drag

Drag has a huge effect on descending speed. It's possible that your friend is getting into a tighter tuck, which as @ChefFlambe pointed out can even include your leg position. The aerodynamic properties of the bicycle (the frame, rims, spokes, etc.) can also make a difference.

My guess is that rider position is the most likely explanation for your difference in speed. Since you are taller than your friend, it may be harder for you to get into a tight tuck. You mentioned that you think it might be the rims. If this is the case, the front wheel will make a bigger difference than the rear wheel, so you could try swapping front wheels to rule this out.

Pedaling

A cyclist who continues to pedal downhill will go faster than one who is coasting. A bicycle with a higher top gear can be pedaled at a higher speed, and a cyclist who can ride at a higher cadence may have an advantage.

To rule out pedaling as the explanation, try going downhill with both of you coasting.

Rolling Resistance

Tires with high rolling resistance are slower than tires with low rolling resistance. Factors include not only tread type and width, but also the type of rubber and casing.

If you both have similar 700x23c wheels at roughly the same pressure (or slightly higher for the heavier rider), then you can rule this out.

Friction

Friction in the hubs will slow down a bike, but this force is probably insignificant unless there is a problem with bearings.

Another source of friction is in the freehub or freewheel, which will be ratcheting (clicking) while coasting.  The friction may be difficult to compare against your friend's, however, unless you remove a lot from each of your rear hubs.


Aero road bike frame - frame size number vs actual frame size? I'm encountering some confusion on frame size and any clarification would be greatly appreciated.  I've always been under the impression that a stated frame size was the distance, usually in cm, from the top of the seat tube to the center of the BB opening.  For example looking at any of the road bikes on the Trek site:

http://www.trekbikes.com/us/en_US/bikes/road-bikes/c/B200/

For all the bikes the "Frame Size Number" and the "Actual Frame Size" (see the chart at the bottom of the page for any of the bikes) are the same, even for the aero Madone.

I'd like to purchase a Dengfu FM098 frame for a bike I'm planning on building:

http://dengfubikes.com/ROAD_FRAME/129.html

The available sizes are listed as "49/52/54/56/58/61cm", but upon going to the Geometry tab this chart is shown:

It would appear that the first column (which is oddly untitled) would correspond to the available size, but dimension "A" is different than the frame size on each line!

At first I figured this was a mistake or an oddity for this particular frame, however the Dengfu R02 (choosing the "Geometry" tab again):

http://dengfubikes.com/ROAD_FRAME/131.html

and the Hongfu FM098:

http://www.hongfu-bikes.com/html_Products/Road_Frame/Aero_Road_Frame/2016/1113/2017%20new%20aero%20road%20frame%20FM098.html

Have the same frame size number vs actual frame size difference.

Can somebody clarify this?  Is this standard in the industry for aero frames or frames with a curved or non-flat top tube?  Is the idea that I should know what size I should be in a flat top tube frame, for example 52cm, then purchase the frame with the name "52cm" even though it is not actually 52cm?  Please advise, thanks!

The answer is the top tube is not straight but curves down at the seat stem.

The idea behind the difference is that somebody who need a 49cm size frame would have the seat adjusted to their leg length and somebody who as a slightly smaller leg length can't lower the seat to suit. So you have got 10 mm up and 10 mm down otherwise your seat would be set at the top of the seat tube all the time. Same on the next size if you bought  a 49cm frame but your leg length is that bit longer you buy the next size up and lower the seat to the top of the seat tub.

You have a 49cm frame with +/-10mm, and the next size frame is a 51cm with plus and minus 10mm. Plus you can work out your crank length from 165 mm to 175 mm to suit your leg length.

So this mean you have some 40 mm to play with in various leg lengths. And the same with your cage length. Or top tube as some people say. If you've got short arms you use a small handle bar stem or long arms a longer handlebar stem.

I hope this may give some of you some better idea and thought to buying your frame. Measure your leg length and subtract 30mm from that and work from there.

I know this as a fact as I design cranks for a living. Hope you have something of a better idea now.