While what NoRacer sez about external BBs is true, it really only takes 15 minutes to change cranks. Also, externals mean Barry's got to buy a new crank as well, which really doesn't seem nec. just to adjust gearing.

I'm curious why it is difficult to put a bottom pull front derailleur on your Trek? Does the XtraCycle bump into it?

A new bike is great, but I bet all you need is a new FD. -GB