i recently picked up a nice japanese touring frame in my perfect size (24.5" c-t). it was originally built with canti bosses for 27" wheels. the frame is going to be sent for powder coating because it is currently in rough shape. since i'm not concerned about the original paint, i'm also curious if it would make a good candidate for 650B conversion by repositioning the canti bosses, so that i can get some nice 650B fatties on there. that brings up four issues as far as i can tell:

1) canti repositioning: can this be done at reasonable cost? will doing so weaken the fork?

2) bottom bracket height: the drop is 63mm. that's a fairly high bottom bracket, no? and that's good for 650B, right?

3) tire clearance / tire choices: since the fattest part of a 650B tire would be approximately 320mm from the axle center, i measured the clearance that far from the front and rear dropouts and came up with 46mm between the chainstays and 45mm between the fork blades. while that would probably exclude using 41mm hetres with fenders (unless the fenders were modified), what other decent 650B tires options exist in the 35-40mm range?

4) appearance: how would 650B look on such a large frame? would it look "off"? can anyone post pictures of their large-frame 650B conversions?