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I am doing a road bike build at the moment, and needed to fit my BB (External BB). I dont have the tool to tighten it up so too it to my local bikeshopjust to screw in the cups. When i asked about it he said that it would need facing at a cost of £30 (there was paint on the no driveside but it was clean on the driveside so looked like it had been done in the factory.
He said that if it wasnt dont I would go through bearings much faster etc..... giving me abit of a lecture about how essential it was. Anyway I decided I would have it faced but once I walked out of the shop I wondered if it was infact a pointless exercise. It presumes that the BB isnt going to line up correctly without facing it, but what if it does. Any even if it isnt perfect, the price of a new BB is £15 so i would have to go through 3 BB before it would have been worthwhile.
Can anyone fill me in on why it is so essential? Ive not really used this shop before (ive just moved to the area) but I would like to have an idea whether they are a shop that is worth using in the future.
Cheers guys
probably.
maybe.
[i]some[/i] BB shells are a bit squiffy, and this will prematurely kill an external BB.
the easiest way to make sure the faces are square is to run a facing tool over them.
doesn't hurt, it's quick [s]and cheap[/s], and you now know your frame won't kill your BB.
edit: £30?! - that was a bit steep...
Jury is out. In theory if the faces are not parallel the axle will not be aligned to the bearings which wil wear prematurely.
Usually avid arguers for both sides on here.
Facing should mean that he bearings are parallel to each other and thus absolutely perpendicular to the axle, which means that the bearing are under even load and should last longer.
EDIT: cynic-al beat me to it; beg your pardon.
I think its a load of balls to be honest, as the two cups being parrallel relys on the BB shell thread
I can see if there is tons of paint, several mm thick that you would want it done, but I havent bothered with it on any frame since back in the day i got the lecture like the OP and paid a bit to have it done and thought about it after I left. That BB still died, and no quicker or longer than on frames I havent bothered my ass getting faced
as the two cups being parrallel relys on the BB shell thread
Easy to disprove, cups can be moved as you screw them in, then tighten on to the shell faces.
FWIW I didn't bother on my Santa Cruz. Always seemed to me that the bb shell is turned and so faces should be parallel. There's also rumours that the facing thing was made up by shimano after the initiall HT2 bbs all lasted about a week.
Hmm Al you know thats not true, you cannot find any recommendations by shimano to face BB shells.
yeah i thought £30 was pretty steep, so the jury is still out on the shop then!
the shop has been sold a lot of bs by park tools..
Al you know thats not true, you cannot find any recommendations by shimano to face BB shells
I didn't say they did, I just said there were rumours.
Oh and £30 seems well steep, it's a quick job.
I have never bothered and all my BB have lasted well enough apart from cheap ones which are not well sealed.
The rumour/suggestion is that it was made up by the distributors/shops selling external BBs rather than Shimano themselves.
Anyway, I never get them faced for reasons stated already. Never had any trouble or at least never any more than the people I know who have had BBs faced...
Just had my BB faced at LBS, while i waited and free.
And btw, even if you think it is necessary, the £30 quoted by the OP's LBS is taking the p!ss - most shops only [s]rip you off to the tune of[/s] charge you a tenner or so. 😉
I guess I will see what happens when I pick the bike up later on today, I thought posting on here that I would get a hammering for questioning the need for it, at least that was a pleasant surprise, unlike the price!
The BB shell should be turned and threaded as a single piece, the faces should be correct. Some paint and damage may affect the end result so in theory this could solve any problems. But I've never had any problems, all the paint on my frames appears pretty evenly distributed, but may not be on all bikes.
But £30 is mental.
I think its a load of balls to be honest, as the two cups being parrallel relys on the BB shell thread
that's not how it works. it is to do with mating surfaces.
£30 seems steep though. tenner max.
I have scraped the paint off before I have fitted them on new frames just to make sure they are flat and again no facing needed 🙂
If I was fitting an expensive BB to a decent frame I'd face it for free.
A cheap BB or frame I'd do it if the customer asked.