Originally Posted by
juggleandhope
my new question - after reading stuff about the 650b wheels - is whether i could use them to lower the standover height of a bicycle so that i could get a top tube that fit me better. sheldon brown kind of ambiguously cites that as a virtue of the wheel size but then says that it might not actually (need to?) affect standover.
Sure, a 650B wheel will lower your standover. Effective rim diameter is 584mm versus 622 for 700c wheels or 630 for 27" wheels. One problem I've had in looking to convert bikes to 650B is that you need a fairly high bottom bracket in the first place or the result will be too low and you'll have pedal strike problems as you pedal through turns. Another issue is brake reach. If the bike was originally made for 27" wheels, you'd be hard pressed to find brakes that'll offer an additional 23mm reach (630-584/2). Going from 700c to 650B is much more do-able, but again you'd need brakes with longer reach (14mm).
Lots of good info on 650B conversions at these sites:
http://sheldonbrown.com/650b.html
http://www.bikeman.com/content/blogcategory/78/93/
http://www.freewebs.com/650b/index.htm
Neal