650b road bikes (not gravel)

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ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

none wrote:
Tue Jan 22, 2019 4:17 pm
I still have my Kestrel from 1996, still a great ride for long distance/hours in the saddle.
I can't tell if rolling resistance is any different from 650c vs 700c, but
smaller wheels do not keep momentum as well as 700c, you feel the bike slowing down as soon as you stop pedaling.
But smallers wheels require less spokes, Kestrel without seattube compensates well for comfort.
Image
that looks awesome, but it's 650c, isnt it?

ericoschmitt
Posts: 186
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by ericoschmitt

ultimobici wrote:
Tue Jan 22, 2019 8:46 am
On the road, unless geometry dictates 650c or 650b wheels, smaller wheels are not necessarily any benefit. Way back in the 90s ONCE experimented with 650c bikes for mountainous stages. Any benefits they conferred were outweighed by the greater effort needed to keep them rolling.


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The effect on gearing would be OK for me at least. It's that old argument if we actually need an 11t cog. I certainly don't, and I always look for the lightest climbing gear, hence why I'm still riding 3x11 setup. I'd be ok with 8% smaller wheels and 8% lighter gearing! That's with a cassette starting with 12. If anything goes wrong I can always get one with an 11t (and soon 10t with sram)

As for the geometry, my custom bikes all have some funky geometry with steeper seat post and short headtube. With a 52cm top tube they are on the edge of being better with smaller wheels, and all of them give me toe overlap (not a big issue really, but better not to have it).

[a bit offtopic, but not 100%]
My last weird idea was to get 120mm cranks and 38t narrow wide chainring to put some gears in my fixie/tt frame. Cranks arrived last week and chainring today. Theory is that 30% shorter cranks makes you spin nearly that much faster spontaneously, so small chainring does the trick, and 38 = 52 with 170mm cranks. If that works, getting smaller wheels on such a bike would be benefical, since in practice I'll now be 5cm higher on the bike compared to 170mm cranks I have been riding on it. If it works well enough I'll have all the reasons to get a new bike: no more triples, 1x, smaller wheels since now I can get aero wheels and good tubeless tires in 650b. Possibly I could swap the hanger on this existing frame and get a new disc fork for it. Could do the trick too. And then with smaller wheels it wouldn't be so weird to have a 38t chainring on a TT bike... It would be 42~ instead! haha
But all that is still some time far from present time. Let's first see how the short cranks work.

by Weenie


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RocketRacing
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by RocketRacing

I disagree on that. It is about subtle changes in contact parch shape, and tire casing deflection. Plus larger tires have better rollover. Subtle, but it adds up.

thirdsun
Posts: 402
Joined: Fri Aug 06, 2021 3:20 pm

by thirdsun

Sorry to pull up this old topic but there's little information about this topic available.

I'm planning to buy a Canyon Aeroad once it becomes available again. Unfortunately there's reason to believe that Canyon might equip their future specs in sizes 2XS and smaller with small 650B wheels as they have already done with their recent Endurace update.
While I'm sure it fits the frame better, as a small man that needs 2XS I'm worried about those small wheels and their efficiency. Particularly on an Aero bike it feels very counter-intuitive to have all those marginal aero gains reversed by an inefficient wheel set that requires more effort to keep rolling. Are my concerns justified or negligible?

Are there any concrete measurements that show the actual difference in efficiency? Preferably in the context of road cycling. All I can find are vague gravel-related discussions listing the pros and cons without providing actual numbers.
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cberg
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by cberg

thirdsun wrote:
Thu Jan 27, 2022 7:53 pm
Sorry to pull up this old topic but there's little information about this topic available.

I'm planning to buy a Canyon Aeroad once it becomes available again. Unfortunately there's reason to believe that Canyon might equip their future specs in sizes 2XS and smaller with small 650B wheels as they have already done with their recent Endurace update.
While I'm sure it fits the frame better, as a small man that needs 2XS I'm worried about those small wheels and their efficiency. Particularly on an Aero bike it feels very counter-intuitive to have all those marginal aero gains reversed by an inefficient wheel set that requires more effort to keep rolling. Are my concerns justified or negligible?

Are there any concrete measurements that show the actual difference in efficiency? Preferably in the context of road cycling. All I can find are vague gravel-related discussions listing the pros and cons without providing actual numbers.
As it is now the Aeroad SL gets smaller wheels on 2/3XS while the SLX and CFR models all have regular 700c wheels.
Didnt answer your question, but I doubt this will change when they are available again :)

thirdsun
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by thirdsun

cberg wrote:
Thu Jan 27, 2022 9:43 pm
thirdsun wrote:
Thu Jan 27, 2022 7:53 pm
Sorry to pull up this old topic but there's little information about this topic available.

I'm planning to buy a Canyon Aeroad once it becomes available again. Unfortunately there's reason to believe that Canyon might equip their future specs in sizes 2XS and smaller with small 650B wheels as they have already done with their recent Endurace update.
While I'm sure it fits the frame better, as a small man that needs 2XS I'm worried about those small wheels and their efficiency. Particularly on an Aero bike it feels very counter-intuitive to have all those marginal aero gains reversed by an inefficient wheel set that requires more effort to keep rolling. Are my concerns justified or negligible?

Are there any concrete measurements that show the actual difference in efficiency? Preferably in the context of road cycling. All I can find are vague gravel-related discussions listing the pros and cons without providing actual numbers.
As it is now the Aeroad SL gets smaller wheels on 2/3XS while the SLX and CFR models all have regular 700c wheels.
Didnt answer your question, but I doubt this will change when they are available again :)
That's the current situation and I hope it stays that way but last week's Endurace update seems to indicate that this may change. The Endurace CF SL uses small wheels and women's geometry in 2XS and 3XS since this update, which wasn't the case before.

Remember that the Aeroads likely won't just re-release in their current spec but will rather get new group sets, colors and spec updates.
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Miller
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by Miller

The difference in wheel diameter going from 700 to 650b is, what, 38mm? I can't believe that's going to make a perceptible difference in efficiency.

shimmeD
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by shimmeD

Agh, obsession with small differences (marginal gains).
If you're a small cyclist and you're better served by a 650 wheeled bike, you're better off not giving time to such obsessions.
Less is more.

thirdsun
Posts: 402
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by thirdsun

Well, the thing is that I have a current Canyon Endurace in 2XS with 700C wheels and toe overlap, while present, is a non-issue for me. Handling is fantastic. Therefore I feel I'm much better served by the more efficient, common wheel that doesn't require me to stock and carry separate, harder to find spare parts/components (like latex tubes).

Also, with the Endurace I understand that it's a negligible issue as it's meant to used on slower rides. However on an Aero bike it seems counter intuitive.

Maybe the difference is really meaningless - I just like to see some measurements.

I found this article: https://www.renehersecycles.com/myth-19 ... re-faster/ - they measured a 10 Watt difference at 32 km/h and call it meaningless. I'd say that's rather significant. Unfortunately they also use very wide, low pressure tires. I don't know how this affects the results compared to road tires.
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  • Cervelo Caledonia Rival eTap AXS
  • Vitus Venon Evo
  • Canyon Grail CF SL 8 Di2

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Miller
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by Miller

There was a moment in the late 90s when time trial bikes with 26 inch wheels were the latest thing.

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ultimobici
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by ultimobici

Miller wrote:There was a moment in the late 90s when time trial bikes with 26 inch wheels were the latest thing.
And happily they died a quick death. Better aerodynamics & lighter weight were outweighed by inferior inertial behaviour & poor choice of tyres. 650b has benefits that are best suited to mixed surface riding where a fatter tyre is needed without too bigger diameter. 650c is suited to smaller bikes where toe overlap increases to a problematic level. If you’re a regular sized rider looking to eliminate it on a road bike, sell the bike and go back to the links. ;)


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Karvalo
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by Karvalo

ultimobici wrote:
Sun Jan 30, 2022 1:01 pm
Miller wrote:There was a moment in the late 90s when time trial bikes with 26 inch wheels were the latest thing.
And happily they died a quick death. Better aerodynamics & lighter weight were outweighed by inferior inertial behaviour
Inferior imaginary behaviour I'd say.

cberg
Posts: 320
Joined: Wed Jan 13, 2021 11:30 am

by cberg

ultimobici wrote:
Sun Jan 30, 2022 1:01 pm
Miller wrote:There was a moment in the late 90s when time trial bikes with 26 inch wheels were the latest thing.
And happily they died a quick death. Better aerodynamics & lighter weight were outweighed by inferior inertial behaviour & poor choice of tyres. 650b has benefits that are best suited to mixed surface riding where a fatter tyre is needed without too bigger diameter. 650c is suited to smaller bikes where toe overlap increases to a problematic level. If you’re a regular sized rider looking to eliminate it on a road bike, sell the bike and go back to the links. ;)


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Benefit of 650c on small road bikes is that you can make the geometry more similar to larger sizes and possibly get the intended handing from the bike, instead of being stuck with weird HT and ST angles

WorkonSunday
Posts: 540
Joined: Tue Jan 16, 2018 4:39 pm

by WorkonSunday

what you gain in bike handling will far outweight aero gain. my wife uses 650b (as mentioned, ATR and Prime Kanza) for most rides but use a 700c triathlon bike if the course doesnt involve any hairpin. She gets some serious toe overlap issues with 700c. shes very tempted to remortgage the house and custom build a 650b trialthon bike. she just hates 700c that much, lol.

a tip for future reference, decathlon does "650" inner tubes (without a,b,c designation), if you read on the side of the box, it can cover 650b as well. My wife uses these with GP5000 non-TL 28mm most of the time if not running tubeless.
Some say pour 10ml water out of your bottle to save that last bit of the weight. Sorry, i go one step further, i tend to the rider off my bikes. :thumbup:
n+1...14 last time i checked, but i lost count :mrgreen:

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