Originally Posted by
auchencrow
A cartridge bb is a good idea ( especially if you rack up the miles on this bike and are remiss in servicing the bearings!)
PS - I can't speak for "Phil" cartidge bb's, but based in my limited experience with Shimano cartridge bb's, I'd plan on replacing it often.
I'm having trouble reconciling the two sentences. Why would it be considered a "good idea" if one should "plan on replacing it often"?
I wouldn't consider actually replacing a properly functioning BB, but it might be reasonable to get spare parts if you anticipate availability issues in the future. OTOH, I picked up a spare headset for my tandem after it started to develop slight 'indexing' in the late '70s. But replacing the ball cage in the existing headset cured the indexing issue and the spare headset is still sitting somewhere in my garage waiting for the original part to fail.
Zinn's recommendation to replace bars and stems is a different situation since those parts sometimes fail suddenly and result in serious injury - especially for riders who put a lot of stress on the bars.