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Will 650b wheel fit a pure road disk frame?

by adam900710
Wed, Aug 29, 2018 05:55
11

Hi,

I'm wondering if it's possible to fit 650b wheel with 35~38mm tire to my Giant TCR disc adv frame, which frame tolerance is around 700x28.

It may sound crazy, but one of my climb routines is cobble and steep.

My current 700c 25mm tubeless setup tends to skid when out of saddle and it feels really terrifying.

Not to mention downhilling with such skinny tire. I have to stop several times to allow my plam to recover.

It's possible to buy a proper gravel bike, but it would be really awesome if I could just fit a 650B wheel with wider tire to my existing pure road bike. For cobble climb/downhill just go with 650B wheelset, and for normal tarmac go with 700C wheelset.

Thanks.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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11 comments

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SteveAustin | 6 years ago
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i would say no. my tcr wouldnt take it as the stays are tapered inwards (slightly narrower nearer the wheel spindle) so wouldnt matter if the wheel was smaller than 700, your bike might be different.

easy to test out. a 650 wheel tyre will be about a cm-ish smaller, so find something 40mm wide and see if that will fit in chainstays/seatstays about a cm smaller than the where your 700 wheel normally sits. anything too close will saw through your frame 1st ride

 

imho. its new bike time, something that will take wider tyres if thats what you want

 

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Crashboy | 6 years ago
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Have you seen this:

 

http://www.bikecalc.com/wheel_size_math

 

Don't know how accurate it is but might help a bit?

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johnvrcc | 6 years ago
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Do you know what model/year the Canyon Endurace disc was? I have a 2016 which fits 35 x 700c and I had been wondering what I might be able to fit with 650b

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Mathemagician | 6 years ago
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For what it's worth, I have an Endurace AL Disc with 28mm Schwalbe Pro Ones set up tubeless. Ridden on some bumpy stuff, including cobbles on hills, and some steep stuff with bad road surfaces. Everyone is different but I've had no comfort issues.

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adam900710 | 6 years ago
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Already running tubeless for my 25mm setup, 70 psi front and 80 psi rear, still pretty hurt down hill.
It looks like the only valid way is going 28mm, which is the max supported tire width (and in fact I'm wondering if 28mm can even fit if mounted on wider rim).

I found one trying the same way on Canyon Endurance disc, but failed even to fit 35mm tire, and it would lower the BB, just as mentioned by BBB.
For TCR disc, it has even less clearance, so I'm going to order a pair of pro one 28mm.

Thanks for all the advice!

Avatar
BBB | 6 years ago
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Try fitting the widest tyres you bike clears first and run them at lower pressure. Unless you weigh a lot, 28mm tyres can be easily run at 70-80PSI and even less at the front, particularly tubeless.

Your choice of fast 650B 35-38mm tyres will be limited. I can think only about Schwalbe G-Speed and Panaracer Gravel King in 38mm but not much is available in 35mm. Another thing to bear in mind is lower bottom bracket height with a 650b setup although it's easy to get use to it after a number of pedal strikes;-)

Best advice is to get a bike with sensible tyre clearance...

 

Avatar
CXR94Di2 | 6 years ago
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the radius of 650b wheels 292mm, measure from spindle that distance, add another 35mm and see what width you have.

compared to 700c are 311mm radius. So measure where the 700c rim is, this should give you a guide of width

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adam900710 | 6 years ago
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Several local bike shops have 650 wheelset, but no such tire.

I could try to go and try wheel only, but still not sure about the tire part.

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StraelGuy | 6 years ago
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Why don't you phone a few local bike shops and see if anyone's got a set of 650B wheels in for you to try?

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adam900710 | 6 years ago
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The problem is I have no 650b wheel/tire at hand. Thus not sure how to measure.

From datasheet, 650B rim bed should be 19mm lower than 700C rim bed. (half the diameter difference)
But I'm not pretty sure how wide a 35mm tire mounted on 650b wheel will be.
(My 25mm Pro one mounted on my 700c wheel is about 27mm wide.)

If just using the theoric value, it should be just 5mm wider but 19mm lower each side, which looks still pretty dangerous for my frame (dead on clearance for the fork, but frame has more generous clearance)
But if something went wrong, I could just waste a pair of new wheels.

Another concern is, such convert is mostly done on gravel bike which already has generous clearance.
But for pure road frame, the clearance is pretty tight, so that any tolerance miss could lead to a disaster so I'm pretty cautious here.

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CXR94Di2 | 6 years ago
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Yes you can, just measure the gap where a 650b tyre will sit to allow a larger tyre. wasted exercise if chain and seat stays don't flare enough.

I have a Tripster V2 which can take 40mm in standard and 55mm with 650b wheels

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