BB shell – to face or not to face

About to build up a 456 frame with an HT2 BB.

Would you have the BB shell faced or not bother?

I would. It’ll cost next to nowt and at least it’s done.

I would & both On-ones I’ve had needed the BB shell tapping too

Yup, best to get it done. Its not so critical with Octalink, ISIS or Sqr Tpr, but just better to get it done when running HTII. At least then you know the faces are perfectly square, meaning the bearings have the best chance of lasting well.

Unless of course you install it with a sledgehammer, a brick or something similar…

Thanks for your opinions.

I was thinking of getting it faced, but I wanted see what the concensus was first.

I’ll be getting it sorted when I can get my lbs to do it.

copy of my answer a week or so ago

(somebody please tell me why I’m wrong – I don’t ride enough to find out for myself (HTII for 18 months so far))

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I just don’t get this facing lark

BB shell has a thread in either side. cups screw into thread to a depth of, what, about 2cm ?

Won’t the opposition of the 2 cups be dependent on the accuracy of the thread-setting, not the ends ?
(surely it’d take a lot of force to warp one of the cups and it’d more likely just sit there, butting up to one bit of the shell – unless it was fitted using a tractor spanner, by a gibbon)

on bb maybe not (althouh i don’t see why you wouldn’t when using ht2)but i did it on head tube and was surprised how uneven the tubes were.

scaredypants – Member

copy of my answer a week or so ago

(somebody please tell me why I’m wrong – I don’t ride enough to find out for myself (HTII for 18 months so far))

—————————-

I just don’t get this facing lark

BB shell has a thread in either side. cups screw into thread to a depth of, what, about 2cm ?

Won’t the opposition of the 2 cups be dependent on the accuracy of the thread-setting, not the ends ?
(surely it’d take a lot of force to warp one of the cups and it’d more likely just sit there, butting up to one bit of the shell – unless it was fitted using a tractor spanner, by a gibbon)
I am sure it would not take much force to slightly deform an alloy cup when tightening it with a foot long lever and if it costs about the same as a new BB but removes any doubt about installation causing problems it strikes me as a good plan. Peace of mind. That’s why I did it anyway.

following the fitting instructions, is more important than facing

would not take much force to slightly deform an alloy cup when tightening it with a foot long lever

well,the way I see it, the force you’re applying with your lever is rotational. Rather than actually your lever “crushing” the cup into the shell, the threads pull the cup in as they turn into the shell.

I still don’t see it (& wouldn’t really give it beans when fitting a cup anyway – I’d rather use a bit of threadlock and just nip it up. Should they be ded tight ?)

If one side hits a high spot and cannot get pulled in further, and the rest gets pulled in, then it is potentially not square any more.
All guesswork but seems to work, in my head anyway.

following the fitting instructions, is more important than facing

From the Shimano instalation instructions…

“Face and chase the BB shell. This will ensure
that the bearings are properly aligned and will
prevent excessive bearing wear and creaking.”

so, not a shop conspiracy after all then :o(