I'm thinking of upgrading my M540 (Deore/LX) cranks with M770 XT cranks. My existing external Shimano external BB seems to be working just fine, would it be advisable to replace the BB when installing the new cranks? If the inner ring spins smoothly is it okay to reuse the existing one?
Assuming the old BB is working and compatible with the new crankset, no benefit could be derived from replacing it, so leave it alone until it needs replacement. Many people remove perfectly good components, and carefully put them in the basement, figuring they'll use them later on either as a backup, or on a "B-bike" The reality is that most of this time these are never used again.
Save your dough and leave the old one in place, and save the new one for when you need it.
This is an older thread, you may not receive a response, and could
be reviving an old thread. Please consider creating a new thread.
Mountain Bike Reviews Forum
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!