# Swapping 27 in wheels with 650b.



## dirttorpedo (Feb 20, 2009)

I know lots of people convert 27 inch wheeled vintage bikes to 700c. If thats possible would you be able to convert a 27 in to 650b? 

If its possible is it a good idea?


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## LC (Jan 28, 2004)

Even if you could find a long enough reach brake it would perform very poorly as you would lose too much braking power. I have a bike with 57mm reach brakes and even they have a definite lose of power from short reach brakes.


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## dirttorpedo (Feb 20, 2009)

LC said:


> Even if you could find a long enough reach brake it would perform very poorly as you would lose too much braking power. I have a bike with 57mm reach brakes and even they have a definite lose of power from short reach brakes.


Interesting - I would have thought that going from 27in to 650b (also called 27.5 in) wheels wouldn't have the same reach implications as going from 27 in to 700c. I'd read in some of the 27 in to 700c threads that some of the old caliper brakes had sufficient reach to work effectively on both wheel sizes.


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## ergott (Feb 26, 2006)

650B is 1.5" smaller in diameter than 700C which in turn is smaller than 27".

The same people that call 650B rims 27.5" are the same people that call 700C 29" so you can see it's not the same as the 27" you are thinking about.


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## dirttorpedo (Feb 20, 2009)

Oy, all of these different naming standards hurts my brain!


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## Kerry Irons (Feb 25, 2002)

dirttorpedo said:


> Oy, all of these different naming standards hurts my brain!


No need for brain pain. Read and learn: sheldonbrown.com/tire-sizing.html


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## JCavilia (Sep 12, 2005)

Yeah, as Kerry said, read Sheldon. A standard system based on the bead seat diameter was adopted by ETRTO decades ago, and if everybody used that these comparisons would be easy (27" is 630mm, 700C is 622mm, 650B is 584mm). But manufacturers continue to use the old ones (often alongside the ETRTO; e.g., a 700C tire also has "622" printed on it). So we still get the massive confusion. There are, I think, seven different rim diameters (all incompatible, of course) that are sometimes designated "26 inch."


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## dirttorpedo (Feb 20, 2009)

Kerry Irons said:


> No need for brain pain. Read and learn: sheldonbrown.com/tire-sizing.html


Ya, my bad. I didn't go to Sheldon because I assumed anything rated in inches was uniform. :blush2:


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