Home install ok or do these really need doing by an LBS?
Currently have an old Shimano square taper BB with some non-groupset cranks. Cranks and chainrings are pretty work after two years of abuse / neglect and was wanting to put either new SLX or XT ones on but they all seem to run on the newer external bottom brackets.
I've got the tools / know-how to change myself but I've read that when fitting an external BB you need a competent LBS to face the frame first so thought I'd better ask the collective hive mind for advice before proceeding.
I've never faced a frame and fit them at home all the time. My bearings seem to die more from water ingress than poor alignment.
(this doesn't mean I shouldn't have had them faced, of course)
Press the threads up to one another and turn in the appropriate direction.....
Home.
HT2 bearing tolerance is enough to deal with slight frame imperfections...according to data from someone here. (bencooper?)
Depending on the BB be careful to make sure it threads straight, the Hope ones seem to have a meatier thread so it's possible to damage if your absent minded.
Yep, the whole "you need to face your frame or kittens will die" was banded around hugely when outboard bearings became popular and died quickly, but not necessry in 99.99% of cases IME.
it is an easy do at home job. and after a few times you'll be able to do it in 5 minutes, everythings a bit akward and hard the first time.
It's a doddle, about as difficult as fitting pedals.
It is an easy job, but if your worried about the 'facing' either pop it to your LBS to have it faced/crankset changed or just ask them to face it for you & you do the rest. Either way you'll be swapping the BB soon enough when it dies 😈
If your BB shell has a lovely clean, sharp outer edge then it was probably faced at the factory and you'll be fine.
If it doesn't look that sharp or still has paint on it then I'd get it faced, it's a one-off job, when you're done you're done.
If it saves you 1 bb over the lifetime of the frame then it'll have paid for itself.
Good , bad, indifferent, right or wrong. The whole facing thing gets me, this is my reasoning...if the original bb in the frame of my mass produced f/s bike lasted ( in my view) an acceptable length of time , in my case almost two years ,despite the bike perhaps not being ridden as often as it is now and was still used in the ,horrid ,winter ,,muddy conditions we have locally, bearing in mind also , that it was a lowly Shimano jobbie, had the frame not been produced to adequate tolerances in the first place, wouldn't it have worn out months previously ?
No bb issues I've had since could ever be put down to not having the frame faced.
I'll agree to differ in the face of reasonable argument though, but it will need to be a good one.