Originally Posted by ruirui

on my current ride (sirrus modified with TT handlebar setup) has ultegra 8/9 speed barcon with sora crank and sora front & rear deraileur. i'm looking to upgrade the crank to a Ultegra Crank Set. i rarely use the smallest chainring in the front.. and the largest on my current setup is a 50T.

so the question is.. can i just change the crankset, or would i have to be changing the chain & the front & rear deraileurs as well? if in the event i have to change the deraileurs.. then what if i were to change the rear 8 speed cassette to a 9 speed.. would i need to get a new cog?