Adaptive Cycling: Handcycles, Amputee Adaptation, Visual Impairment, and Other Needs Have a need for adaptive equipment to ride to compensate for a disability or loss of limb or function? This area is for discussion among those of us in the cycling world that are coming back from traumatic circumstances and tell the world, "No, you are not going to beat me down!"

Why not 650b??

Old 06-30-20, 05:30 PM
Senior Member
Thread Starter
showlow's Avatar
Join Date: Sep 2014
Location: Tucson
Posts: 210

Bikes: Surly Cross Check, Lemond Zurich, All City Zig Zag

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked 26 Times in 17 Posts
Why not 650b??

In the marketing material for my bike frame it says that 650b isn't recommended because the frame isn't "designed" for it. Given that a slightly larger tire on a 27.5/650b wheel has the nearly the exact same diameter as a 700c wheel with a smaller tire, then what could the issue possibly be? What is meant by the bike not being "designed" for 650b?

Edit- sorry, wrong forum. Possible to move to mechanics?

Last edited by showlow; 06-30-20 at 05:39 PM.
showlow is offline  
Old 07-01-20, 09:23 AM
Senior Member
friday1970's Avatar
Join Date: Sep 2012
Location: Brighton, Michigan
Posts: 476

Bikes: Optima Baron LR, '14 Nishiki Maricopa,'87 Trek 330 Elance, '89 Miyata 1400, '85 Peugeot PGN10, '04 Fuji Ace, '06 Giant Rincon, '95 Giant Allegre, '83 Trek 620, '86 Schwinn High Sierra

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 159 Post(s)
Liked 61 Times in 41 Posts
What I know about converting to 650B is really about two things. Brake reach and pedal-to-ground clearance.
I recently converted an older Trek 330 to 650b. My only issue was the original brakes didn't reach far enough, so I had to modify the frame for modern recessed screw brakes and then use a pair of Tektro brakes that did reach. I can fit 38mm tires with no issue. I might be able to fit 42's too, but haven't tried.
I use 170mm cranks, and since the bottom bracket is high enough on this "sport touring" frame, I've had no issues with pedals hitting the ground.
So really, the frame wasn't exactly designed for 650b per se, but it does work with well as a 650b. I am loving the plush ride of larger tires and lower pressures.

Last edited by friday1970; 07-01-20 at 09:27 AM.
friday1970 is offline  
Old 07-01-20, 02:20 PM
fietsbob's Avatar
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 42,551

Bikes: 8

Mentioned: 194 Post(s)
Tagged: 0 Thread(s)
Quoted: 7317 Post(s)
Liked 915 Times in 577 Posts
27.5" is same as 650B smaller rim fatter tire ..
fietsbob is offline  
Old 07-15-20, 05:28 AM
Senior Member
shelbyfv's Avatar
Join Date: Jun 2007
Posts: 6,815
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 1660 Post(s)
Liked 920 Times in 557 Posts
Did you ever determine why?
shelbyfv is offline  
Old 07-15-20, 10:13 AM
Senior Member
Join Date: Mar 2019
Posts: 64
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Liked 27 Times in 21 Posts
Could be there is no specific reason why not, but the company just never tested the frame with 650 wheels. If you put 650 wheels on and the bike handles a bit funny and you end up getting run over by a dump truck, you can't say it was their fault because they never told you not to use 650 b wheels.

If you've got 650b wheels on hand that will work, and you acknowledge that you are taking the (admittedly very small) risk yourself, then go for it.

It also could be an issue of geometric limitations. Yes, putting 42mm tires on a 650b rim will give it a similar diameter to a 700c wheel, but what if such wide tires don't fit... maybe the space between the chainstays will only allow 32mm tires at the point where 650b tires would be, so you can't physically fit the hypothetical 650b wheels with the same diameter.
ClydeClydeson is offline  
Old 07-15-20, 11:41 AM
Senior Member
Join Date: Jan 2020
Location: San Jose
Posts: 216

Bikes: Topstone AL 105 / SystemSix Carbon Ultegra

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 84 Post(s)
Liked 51 Times in 38 Posts
It's a lot easier to say no dog allowed in the park than to say "only good well behaved dogs allowed".

You have to get a lot of things right when swapping to 650b wheels. As others have said if you have rim brakes they will not work. You might be lower to the ground where you pedals might hit on some turns or terrain. Seems like most 650b rims tend to be wider ( moutain/gravel bike ) so maybe the tires or too wide. Seems like a lot of 650b wheels have 9 Spd cassette vs 700c wheels that have 11+ speeds. Of course you can get around all that but it's a lot easier to say it's not recommended.
sean.hwy is offline  
Likes For sean.hwy:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.