Originally Posted by
DaveSSS
The BB is 68mm wide, so that limits the DT width to 68mm or 2.68 inches. Big DTs have been around for a long time.
Even an old C'dale 2.8 from '92 has a relatively fat DT.
Nowadays, with integrated external bearing BBs, you can get wider - 90mm or so (Trek's "
BB90" was one of the first ones). There are some other BB numbers being thrown around, with all but Look's BB65 having to do with the width of the shell, not the diameter of the BB spindle. I don't necessarily agree with Trek's BB shell idea but I have to admit that you can make your downtube wider than you could on a 68 mm BB shell.
cdr