Originally Posted by
nlerner
I assume you mean toe-clip overlap, not heel strike? If so, no, it hasn't been a problem. From the chart you link to, the diameter of a 650B x 38mm wheel = 660mm while 700 x 25mm = 672mm, so we're talking smaller.
If you mean heel strike, I'm not sure how that's related, but I don't know much about touring bikes.
If you drop the BB, then the crank arm might clip the ground on a turn assuming you're pedaling; not an issue if you keep the arm up in a turn.
I had a bike once that I converted from 700c to 26 inch. Not a really bright idea I guess but I wanted to use a fatter tire. That bike had heel strike problems but that was a much more radical drop in the BB than we are talking about here.
This is the best discussion I've seen online of some of the measurements you need to take into account when doing a 650b conversion,
http://www.bikeman.com/bikeman-blogs...sion-guidlines
Bottom bracket height is one variable you need to think about; drop it too much and pedal strike becomes a real possibility.