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Modern bike wheels and tires are also moving in an interesting direction: carbon rims are increasingly made 'hookless' (straight flange without the 'hook' which

by tpm 3y ago

Modern bike wheels and tires are also moving in an interesting direction: carbon rims are increasingly made 'hookless' (straight flange without the 'hook' which locks the tire bead) because it's easier to manufacture, lighter and more aerodynamic, while tires are tubeless, which is also lighter and less prone to punctures, but then the tires are harder to manufacture and more expensive. And lower pressures must be used so the tire does not pop off the hookless rim, so the rims and tires are also getting wider to hold more air, where once 17mm inner rim width was common for road bikes, we are now getting up to 25mm.

ubermonkey 3y ago
28mm is actually common. That's what I have on my brand-new Giant TCR (which is to say: an aggressive, go-fast road bike).
- tpm 3y ago
  You are right 28mm is currently a common road tire width, but that's the total external tire width. What I mentioned rising from about 17 to (not yet common, but getting there) 25mm is the inner rim with - the narrowest measure between opposing rim flanges.
  - rhombocombus 3y ago
    As a recovering bike mechanic of 20 years (my retirement goal is to be able to afford doing that job again, it’s joyful but hard to make a living) the writing has been on the wall for several years about the many benefits of wider tires (and rims too I suppose). From fewer puncture flats, to greater comfort and traction, to actually lower rolling resistance, I dknt see a move back to narrower tires being something that ever happens and I couldn’t be happier about that fact! I’m too slow and old to reap any performance benefits, but my comfort and enjoyment of wider tires makes me ride my bike more. https://www.renehersecycles.com/bq-tire-test-results/ https://www.renehersecycles.com/bq-tire-test-results/
    - tpm 3y ago
      Completely argee - I use 35mm tires on my 'road' (repurposed gravel) bike since ages because I just like it that way and never felt the need to go narrower.
  - usrusr 3y ago
    C17 rims are considered very narrow in road cycling these days. It's been a few years since 17mm were new and upcoming. Campagnolo widened their Zonda wheelset to C17 in, easy to remember, 2017 and they were late. The goal of performance oriented riders (for many, fixated might be the more accurate description) these days is to run the widest possible rim that will still hold their tire width of choice reasonably well. This has several reasons. One is that wind tunnel treats have repeatedly shown that there's an aerodynamic sweet spot where the rim is slightly wider than the tire, despite the increase in total frontal area for a given tire width (google "105 rule"), another is that riders want the suspension benefits of lower pressure but as little as possible of the downsides of the extra drag of wider tires, the extra mass of wider tires, increased danger of pinch flats and decreased lateral stability. Wider rims help with all those compromises.
wiredfool 3y ago
Lower pressure is required with wider tires (stress in the tire casing is proportional to P*r). Which is good, because it turns out that lower pressure, when coupled with flexible tires, is actually lower resistance than high pressure. Tubeless "just" allows for lower pressures without pinch flatting. The lower limit on pressure is to have enough to keep the bead seated, and not burping air. If you run lower than that, you've got to go tublar.
- Animats 3y ago
  The seal between wheel and tire in a tubeless tire is good enough to hold air for months to years. That's incredible, when you think about it.
  - justinator 3y ago
    For bicycle tires (at least), this is true I guess, but the sealant is going to degrade to the point where one may not be able to ride that bike that's been set up tubeless for a few years, without changing out the sealant.
  - loeg 3y ago
    Maybe in cars at 30 PSI. In bicycles at road pressures (60+ PSI), even with sealant you lose a few PSI every day.
- loeg 3y ago
  > Which is good, because it turns out that lower pressure, when coupled with flexible tires, is actually lower resistance than high pressure. Yes, on rough (real world) road surfaces, rolling resistance is lower. (Ignoring aerodynamic drag of a larger tire profile.) On smooth surfaces like velodromes, skinny tires at stupid high pressures are faster. (I only bring this up because I race at a velodrome.)
mauvehaus 3y ago
Hookless rims are actually a pretty old technology. I had a beater 10-speed from the '70s with hookless ISO 630 aluminum rims. Then as now, they tend to run a lot tighter tires than hooked rims, and that bike, as are many newer ones with TLR rims, was kind of a bastard to change a tire on. Source: Among other things, I work at a bike shop part-time and have volunteered as a bike mechanic in the past.
- justinator 3y ago
  But these were with tubulars, yes?
  - mauvehaus 3y ago
    On my beater? No. Hookless rims for clincher tires. No idea why, but common enough that the bike coop I got it at had a standard down charge for them.
loeg 3y ago
Hookless for road bikes is a dead end manufacturing fad that only exists to increase manufacturers' margins. It does not provide any aerodynamic benefit. The weights are not substantially different. The low tire pressure maximums are not suited for road tires. The manufacturing cost savings are not passed on to consumers. Hookless might improve strength in a way that matters when tires are flat or otherwise bottom out (i.e., maybe useful for MTB, where the pressure maximums are not a concern). Hooked wheels are moving wider, too, of course. 21mm internal is now relatively common and you also see 22-24mm internal road wheels.

by tpm 3y ago

ubermonkey 3y ago

28mm is actually common. That's what I have on my brand-new Giant TCR (which is to say: an aggressive, go-fast road bike).

tpm 3y ago
You are right 28mm is currently a common road tire width, but that's the total external tire width. What I mentioned rising from about 17 to (not yet common, but getting there) 25mm is the inner rim with - the narrowest measure between opposing rim flanges.
- rhombocombus 3y ago
  As a recovering bike mechanic of 20 years (my retirement goal is to be able to afford doing that job again, it’s joyful but hard to make a living) the writing has been on the wall for several years about the many benefits of wider tires (and rims too I suppose). From fewer puncture flats, to greater comfort and traction, to actually lower rolling resistance, I dknt see a move back to narrower tires being something that ever happens and I couldn’t be happier about that fact! I’m too slow and old to reap any performance benefits, but my comfort and enjoyment of wider tires makes me ride my bike more. https://www.renehersecycles.com/bq-tire-test-results/ https://www.renehersecycles.com/bq-tire-test-results/
  - tpm 3y ago
    Completely argee - I use 35mm tires on my 'road' (repurposed gravel) bike since ages because I just like it that way and never felt the need to go narrower.
- usrusr 3y ago
  C17 rims are considered very narrow in road cycling these days. It's been a few years since 17mm were new and upcoming. Campagnolo widened their Zonda wheelset to C17 in, easy to remember, 2017 and they were late. The goal of performance oriented riders (for many, fixated might be the more accurate description) these days is to run the widest possible rim that will still hold their tire width of choice reasonably well. This has several reasons. One is that wind tunnel treats have repeatedly shown that there's an aerodynamic sweet spot where the rim is slightly wider than the tire, despite the increase in total frontal area for a given tire width (google "105 rule"), another is that riders want the suspension benefits of lower pressure but as little as possible of the downsides of the extra drag of wider tires, the extra mass of wider tires, increased danger of pinch flats and decreased lateral stability. Wider rims help with all those compromises.

wiredfool 3y ago

Lower pressure is required with wider tires (stress in the tire casing is proportional to P*r). Which is good, because it turns out that lower pressure, when coupled with flexible tires, is actually lower resistance than high pressure. Tubeless "just" allows for lower pressures without pinch flatting. The lower limit on pressure is to have enough to keep the bead seated, and not burping air. If you run lower than that, you've got to go tublar.

Animats 3y ago
The seal between wheel and tire in a tubeless tire is good enough to hold air for months to years. That's incredible, when you think about it.
- justinator 3y ago
  For bicycle tires (at least), this is true I guess, but the sealant is going to degrade to the point where one may not be able to ride that bike that's been set up tubeless for a few years, without changing out the sealant.
- loeg 3y ago
  Maybe in cars at 30 PSI. In bicycles at road pressures (60+ PSI), even with sealant you lose a few PSI every day.
loeg 3y ago
> Which is good, because it turns out that lower pressure, when coupled with flexible tires, is actually lower resistance than high pressure. Yes, on rough (real world) road surfaces, rolling resistance is lower. (Ignoring aerodynamic drag of a larger tire profile.) On smooth surfaces like velodromes, skinny tires at stupid high pressures are faster. (I only bring this up because I race at a velodrome.)

mauvehaus 3y ago

Hookless rims are actually a pretty old technology. I had a beater 10-speed from the '70s with hookless ISO 630 aluminum rims. Then as now, they tend to run a lot tighter tires than hooked rims, and that bike, as are many newer ones with TLR rims, was kind of a bastard to change a tire on. Source: Among other things, I work at a bike shop part-time and have volunteered as a bike mechanic in the past.

justinator 3y ago
But these were with tubulars, yes?
- mauvehaus 3y ago
  On my beater? No. Hookless rims for clincher tires. No idea why, but common enough that the bike coop I got it at had a standard down charge for them.

loeg 3y ago

Hookless for road bikes is a dead end manufacturing fad that only exists to increase manufacturers' margins. It does not provide any aerodynamic benefit. The weights are not substantially different. The low tire pressure maximums are not suited for road tires. The manufacturing cost savings are not passed on to consumers. Hookless might improve strength in a way that matters when tires are flat or otherwise bottom out (i.e., maybe useful for MTB, where the pressure maximums are not a concern). Hooked wheels are moving wider, too, of course. 21mm internal is now relatively common and you also see 22-24mm internal road wheels.