I'm looking at trimming my bikes down to one: a cannondale cx bike. I would like gears a low as my current MTB ( giant anthem 29 er) which is a shimano xt double chainring setup. Could I ( well, a shop actually) fit a xt double setup on this bike? I'd also like to keep ultegra sti shifters, will xt work with these? If not, what are the implications? MTB brake levers and barend shifters? Any advice appreciated.