Going from 28mm tires on 700c rims to 35mm tires on 650B change anything?

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kode54
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Joined: Tue May 23, 2006 9:39 pm

by kode54

Thinking about getting a set of 650B wheels so I can fit wider 35mm tires on my Moots. Mainly for winter and poor riding conditions, and on ocassion, 10% gravel riding if I can find any gravel roads along the way.

Will this affect handling on my Moots Vamoots Disc RSL? I'm on 28mm tires with 700c Enve 3.4AR rims. Anyone do this?
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spdntrxi
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by spdntrxi

slight... very slight slowing of handling.
BB clearance will lower unless you end up with 650x50+ for similar outer diameter to 700x28 (keep that in mind with rocks and carving corners)
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yinzerniner
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by yinzerniner

spdntrxi wrote:
Mon Oct 07, 2019 9:41 pm
slight... very slight slowing of handling.
BB clearance will lower unless you end up with 650x50+ for similar outer diameter to 700x28 (keep that in mind with rocks and carving corners)
700x28 to 650x35 will induce a 12mm lower BB and axle height, so while handling will be slower due to the larger rubber the trail of the bike will be shrunken, making the steering twitchier. And 12mm lower will make pedal strikes that much more common.

Also the 38mm tire will most likely weigh a lot more than the 28mm, so acceleration aka spin up will take more effort.

kode54
Posts: 3749
Joined: Tue May 23, 2006 9:39 pm

by kode54

Thx for the answers.

So about half an inch...may make a difference in cornering...but going into winter, may not be that critical since I'll techincally be slower with less fitness.
Gettng a gravel bike just to take out on 3-4 rides during the year doesn't make much sense at the moment just to try for gravels sake. I think if I had more gravel roads around me, I would most likely take the plunge for a dedicated gravel bike.
- Factor Ostro VAM Disc
- Factor LS Disc
- Specialized Aethos Disc
- Sturdy Ti Allroad Disc
- Guru Praemio R Disc

WheelNut
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Joined: Fri Jun 22, 2018 11:51 pm

by WheelNut

You'll definitely feel a pretty big difference in the handling of the bike. You'll reduce the trail of the bike, so that'll make the handling feel a bit faster and more reactive.

yinzerniner
Posts: 206
Joined: Tue Jun 13, 2017 8:54 pm

by yinzerniner

kode54 wrote:
Tue Oct 08, 2019 8:41 pm
Thx for the answers.

So about half an inch...may make a difference in cornering...but going into winter, may not be that critical since I'll techincally be slower with less fitness.
Gettng a gravel bike just to take out on 3-4 rides during the year doesn't make much sense at the moment just to try for gravels sake. I think if I had more gravel roads around me, I would most likely take the plunge for a dedicated gravel bike.
A 1/2" or 12mm difference is ENORMOUS when dealing with BB drop and axle height. It's basically the difference in running 28mm vs 40mm tires in the other direction. It will completely change the character of your Moots, which is one of the finest riding bikes around.

If all you can fit is 28mm in 700c or 35mm in 650B I think you'd be better off getting a set of 700c tubulars. Put on some nice supple fast 28mm cx pattern tires, run lower pressures and you'll get at least the comfort and grip of 35mm clinchers if not 35mm tubeless and you won't screw up your handling. As for weight, tubular rims are usually 50-100g lighter than clinchers, so running a heavier cx tubular tire on the lighter rims will keep the rotating mass about the same. Also tubulars will be safer on the grimier winter roads since they handle flats much better.

Marin
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Location: Vienna Austria

by Marin

Have to disagree here, 12mm BB drop difference isn't something you will feel directly.

The thing you feel most is front wheel weight and front tire deformation, which depends on casing, width and pressure.

I run 650b x 38 to 50 as well as 700c x 23 to 35mm in my bikes and that's my personal experience.

kode54
Posts: 3749
Joined: Tue May 23, 2006 9:39 pm

by kode54

thx for that. I may try it to see. Don't have the room for a dedicated gravel bike. I'm hoping that I can get away with just another wheelset at 650B instead of an entire gravel bike.
- Factor Ostro VAM Disc
- Factor LS Disc
- Specialized Aethos Disc
- Sturdy Ti Allroad Disc
- Guru Praemio R Disc

Hexsense
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Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

So.. if my bike can handle 700x32mm. Should i go for 650b x 42mm?
Or while the height is good, the width can be too much for regular road bike?

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

by spdntrxi

Hexsense wrote:
Mon Oct 14, 2019 4:51 pm
So.. if my bike can handle 700x32mm. Should i go for 650b x 42mm?
Or while the height is good, the width can be too much for regular road bike?

I have some doubts 32mm to 42mm is big change.. tires are likely to be wider if inner rim width is low too. Generally chainstays are the narrow part.
2024 BMC TeamMachine R Building
2018 BMC TImeMachine Road
2002 Moots Compact-SL- getting aero look makeover
2019 Parlee Z0XD - "classified"
2023 Pivot E-Vault - completed project, full Xplr package

Marin
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Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

Hexsense wrote:
Mon Oct 14, 2019 4:51 pm
So.. if my bike can handle 700x32mm. Should i go for 650b x 42mm?
Or while the height is good, the width can be too much for regular road bike?
I really like 650 x 42mm. With Pari-Motos or something similar you can ride road and off-road really well.

This chart is helpful: https://www.bikecalc.com/wheel_size_math

As above, usually you are limited by the chainstays.

yinzerniner
Posts: 206
Joined: Tue Jun 13, 2017 8:54 pm

by yinzerniner

Hexsense wrote:
Mon Oct 14, 2019 4:51 pm
So.. if my bike can handle 700x32mm. Should i go for 650b x 42mm?
Or while the height is good, the width can be too much for regular road bike?
Can't know until you've tried it.

On that note, I tried it. Going from 700x25 to 650x38 on a Crux changed the handling and balance mightily. Wheels were Reynolds ATRx 700c and Zipp 303 650b. The chainstaiys on the Crux weren't designed for 650b so the largest points between the stays was at a choke point of the 650x38 and 42s. Clearance of 4mm on 700x40s was same as 650x38, which sound counterintuitive until you remember the chainstay shape is optimized for 700c.

Until you learn by trial and error I think the best bet would be to try more supple tires instead of just larger tires. Numbers are empirical, while riding is not.

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