650b road bikes (not gravel)

Discuss light weight issues concerning road bikes & parts.
ericoschmitt
Posts: 186
Joined: Fri Apr 21, 2017 7:47 pm

by ericoschmitt

Hello, recently Continental has announced the GP5000 in 650b (584mm) size as well. They have it in 25 and 28mm widths, clincher and tubeless.

It seems to me that these are the first narrow road tires for 650b, at least that I know of. Everywhere I searched I only see gravel tires in 40mm++

So does that possibly point to a future with smaller wheels, again? (Remember 650c). Why would conti release a road tire for a wheel size that is only seen in gravel bikes and MTB? For that guy who bought a gravel bike with fancy aero wheels but only rides asphalt and then regrets not having bought a road bike?

There's this reynolds ATR2 650b wheel out there, for example:
https://road.cc/content/review/237817-r ... b-wheelset

And I've seem a couple others like that, that I don't remember the name, around 30mm external width and 40mm or deeper. Those would probably work great in a wind tunnel with these narrower GP5000 tires. I think it was Zipp that stated their 650c model was some 10% more aero just for being smaller... So with a 650b wheel, the size on its own would offset the aero drag caused by disc brakes, and also makes the weight gap narrower.

Personally I really like the news. I would ride 650c (smaller than 650b) if there were good tires and aero wheels available. There are no tubeless models for 650c at all. And all my bikes have some toe overlap. And I like it lighter. But I have all my bikes in 700c now... I'd actually ride mtb 26 inch (erd 559mm) if I could, really, or even smaller like 520mm, but for the sizes I can find good tubulars I only find wheelchair rims...

I'm not building a new bike now just because of these tires, but I do hope they are still around when I decide to build a new machine, and that other tubeless road tires show up too.

So what do you think? Will we have 650b road bikes showing up in the future?

by Weenie


romanmoser
Posts: 252
Joined: Sun May 06, 2018 8:30 pm

by romanmoser

Canyon sell his smaller size ( for women and with '' women '' components but it could be good for small men )
Only with disc brakes wheels tough
Rims 650b are also used in gravel

Maybe you could find some 650b rims with brake track but will be hard

And any custom builder could build you a 650b bike

spdntrxi
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Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

those ATR2... 650b are kinda aimed at the "gravel" market by the way.. you know what ATR stands for ? Personally I think 650b for road only is not going to explode.

RocketRacing
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by RocketRacing

650b for road is not a new thing at all. Cervelo even last gen would spec smaller sized tri bikes in 650b as the wheel size better suits the smaller frames (48/extra small). Norco specs 650b for size small (or less) mountain bike frames.

The advantage of 650b in road bikes would be significant in aerodynamics with the lower frontal area, but i suspect this would be partly offset by higher rolling resistance (less optimal contact patch). The downside is that it is expensive to develop a wheelsize for this niche market. Thus, only big companies, with top selling tires like the gp5000 can make the financial argument to have a go at it.

650b in road is gaining traction in the hybrid/gravel genre with wider options. Kind of like 27.5 plus tires for mountain bike. Allows for lots of comfort/traction.

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ultimobici
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by ultimobici

What is your reasoning for wanting 650b? If your build requires a smaller wheel, fair enough, but if it’s weight and aerodynamics I’d think again.


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Etienne
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Joined: Tue Aug 23, 2005 11:41 am
Location: France

by Etienne

RocketRacing wrote:
Tue Jan 22, 2019 1:22 am
650b for road is not a new thing at all. Cervelo even last gen would spec smaller sized tri bikes in 650b as the wheel size better suits the smaller frames (48/extra small). Norco specs 650b for size small (or less) mountain bike frames.

The advantage of 650b in road bikes would be significant in aerodynamics with the lower frontal area, but i suspect this would be partly offset by higher rolling resistance (less optimal contact patch). The downside is that it is expensive to develop a wheelsize for this niche market. Thus, only big companies, with top selling tires like the gp5000 can make the financial argument to have a go at it.

650b in road is gaining traction in the hybrid/gravel genre with wider options. Kind of like 27.5 plus tires for mountain bike. Allows for lots of comfort/traction.
I think you made a confusion between 650b and 650c wheels ... they are not the same. 650b wheels are equivalent to 27.5" wheels and take the same tires but 650c are smaller, close but not identical to 26" wheels, and often used on smaller sizes road-tri bikes in the past.

I don't think so many recent tri bikes are using 650c wheels, even from Cervélo.

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ultimobici
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by ultimobici

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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NickJHP
Posts: 232
Joined: Wed Feb 14, 2018 2:22 am
Location: Canberra, Australia

by NickJHP

There are quite a few 650b tyres around 28-32mm width:

Ritchey Tom Slick is 650B x 28
Schwalbe make their S-One in 650B x 30
Hutchinson "Confrérie des 650B" is 650B x 32
Grand Bois Cypres is 650B x 32

WorkonSunday
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by WorkonSunday

my wife has been using Schwalbe pro one 25mm with her Fulcrum Red Passion 3 Disc 650b on her Colnago A1r (DB). we got both wheels and tyres from bike24. we swap around between that and Schwalbe G-One 40mm depending on what route we are taking.

I do welcome more choices especially something as good as GP5000. :up:
In the house: Colnago V1r, Colnago A1r, Wilier Cento1 Air, Scott Scale 700SL, Bianchi FSE, Colnago Concept, Colnago A1r, Specialized Ruze Pro, Wilier GTR

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Miller
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by Miller

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.
I find it hard to believe an 8% smaller diameter will have any noticeable effect on rolling resistance. I remember ONCE doing that, Tony Romnger rode one, there was a very brief vogue in the TT scene for the smaller wheels. However tyre and wheel choice was never great, it affected the gearing, and the bikes looked a bit funny under bigger riders. All that for little proven benefit is what killed it.

none
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Joined: Mon Dec 17, 2018 11:29 pm

by none

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.
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Miller
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by Miller

That still looks futuristic.

ericoschmitt
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by ericoschmitt

romanmoser wrote:
Mon Jan 21, 2019 10:22 pm

Maybe you could find some 650b rims with brake track but will be hard

And any custom builder could build you a 650b bike
All my bikes are custom steel, but all 700c because lack of options until recent past. Still too few. Also my road racing bike was conceived 2 years ago, disc was less popular, less options, so I went for 700c rim brake. But in the future...

ericoschmitt
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by ericoschmitt

spdntrxi wrote:
Tue Jan 22, 2019 12:36 am
those ATR2... 650b are kinda aimed at the "gravel" market by the way.. you know what ATR stands for ? Personally I think 650b for road only is not going to explode.
Yes, all terrain road, but with 23 inner you can still use 28mm tires and stay aero with the 105% rule. Maybe even 25 front depending on model.

by Weenie


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

by ericoschmitt

RocketRacing wrote:
Tue Jan 22, 2019 1:22 am
650b for road is not a new thing at all. Cervelo even last gen would spec smaller sized tri bikes in 650b as the wheel size better suits the smaller frames (48/extra small). Norco specs 650b for size small (or less) mountain bike frames.

The advantage of 650b in road bikes would be significant in aerodynamics with the lower frontal area, but i suspect this would be partly offset by higher rolling resistance (less optimal contact patch). The downside is that it is expensive to develop a wheelsize for this niche market. Thus, only big companies, with top selling tires like the gp5000 can make the financial argument to have a go at it.

650b in road is gaining traction in the hybrid/gravel genre with wider options. Kind of like 27.5 plus tires for mountain bike. Allows for lots of comfort/traction.
That rolling resistance argument is pure myth. If the tire has the same construction I bet you wouldn't even get a measurable difference with 16 inch wheels. There has been research on that ever since trains and chariot wheels. As long as you have pneumatic instead of solid wheels, the size won't get you higher Crr.

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