I've just tried to fit a new Hope BB in my BB92 Trek Procaliber (which Trek call a PF92).
However, the bearings are getting pinched, binding quite badly on the drive side (measuring about 0.1mm undersized), not smooth non-drive side either (about 0.05mm undersized).
Has anybody managed to rectify their out of spec frame by reaming or suchlike?
I think I once saw Hambini fixed an undersized frame using a flappy paddle sander which I guess is an option, but I guess a proper reamer would make sure the cup ends up round.
I've honed bearing seats before by hand using Emery paper, fine sandpaper and a piece of dowel.
If you go this route, go steady and measure often to ensure you dont ovalise the bore. Be prepared to put the time in, and walk away when you get bored to prevent rushing it and doing a poor job.
What was the fit of the previous BB like?
I use the Park 744 reamer, reams to 40.98mm.
Frames with an ID too small are not uncommon.
Personally I would take the frame with the BB out to a shop and pay them to do it properly, its a one off job, the tool is expensive, and your next bike will probably have a different BB standard.
If you've no experience with hand tools, this is the last job you really want to do to get some practise. The problem with an emery wheel is you have little control over concentricity or eccentricity. Either find someone with the right tools or a machine shop who can set it up on a milling machine or jig borer.
Dove biker +1.
it's why I did my bearing seats by hand. If you do go slightly wonky, because you're doing it by hand you won't be too far out. Measuring often allows you to catch it.
The flip side is it does take a while to work through the process to get where you need to be.
I just fitted a RaceFace BB92 to my procaliber.
Went in fine with a BB press and a bit of grease but been on two dry rides and already creaking
Not sure that helps but gets it off my chest
😟
pushfit + grease = creak
The previous BB was really crap to the extent that I could feel the resistance when pedalling but previously I wasn't 100% sure if thay was due to it being GXP or the frame cups.
I was starting to think I should call round some shops in West London and see who is appropriately tooled up.
However, i am interested in this dowel method. Is this something I could reasonably expect to do working carefully with a 30mm tube inserted through the BB? Any hints on good methodology?
Woody, did you check the bearing was smooth after you pressed it in? i could get the bearing in ok but it was clearly binding before even trying to install the crank.
I do have the loctite bearing retaining compound, to use rather than grease for creak free installation but need to get the cups vaguely the right size first.
Would one of those Wheels Manufacturing BB92s that thread into themselves help?
🤚
Isn't pf41/bb92 a separately cupped system al a:
The main point being frame tolerances are poor so they aren't intended to take bearings directly?
1. I don't see how screw together cups will help bearings from being pinched.
2. Sort of. Sleeved for 24mm/gxp axle but not for 30mm axle
3. I don't see how sleeves allow for crap tolerance. If the sleeve material is pliant enough to conform to undersized dimensional tolerance then they would also be pliant enough for the bearings to move out of alignment under pedalling loads.
1. I don’t see how screw together cups will help bearings from being pinched.
Just torque it up and the aluminium sleeve will either fit, or its warranty time...
from about 18:00 in
1. I don’t see how screw together cups will help bearings from being pinched.
By actually being the right size for the bearing. They won't prevent pinch in your case though because...
2. Sort of. Sleeved for 24mm/gxp axle but not for 30mm axle
Ah. Bodge job then. (not you specifically, I'm assuming trek, but it's a 24mm standard).
3. I don’t see how sleeves allow for crap tolerance. If the sleeve material is pliant enough to conform to undersized dimensional tolerance then they would also be pliant enough for the bearings to move out of alignment under pedalling loads.
They've been making headset and bb cups to deal with crappy frame tolerances be they steel, alu. plastic for years, I understand and share your reasoning but it's not born out in practice.
(edit Fwiw, as best I can find the specification for pf41 is 41mm nominal with a maximum of +0.00mm -0.10mm)
@twisty - double checked the bearings. They were turning smoothly with no binding.
Followed the RF instructions to use grease (I did think about loctite but didn’t have any to hand) but obvs crap
Might take it out and try again with loctite
Do you still have the old bb? Inspect that, does it show any sign of damage or rubbing? Can you tell from looking at that if there is a high spot?
Is it under sized or just one area thats pinching?
I'm always amazed at how bad bb are when hambini measures them.
Same issue on the GF's Scott Addict road bike. Old Shimano BB was on its way out, I fitted a brand new Hope PF41 BB for her as I have done to many other bikes. Bearings feel notchy, and the whole setup creaks almost as badly as the knackered Shimano BB that came out!
The first time I looked at this the shell looked clean and BB cups are very clean and I did give the shell a quick rub down with steel wool.
However, spending some more time on this yesterday I found that when working around the shell with a straight edge that some stuff did scrape off fairly easily, I guess bonding compound used on the previous BB cups.
Now one side is running smoothly and the other is still binding. I'm struggling to pick up any high spot/size tolerance visually, it's beyond the tolerance of my basic manual vernier caliper.
Think I can get this sorted at the weekend, my first thought is to press in the binding bearing and then see if I can slip in a 1thou feeler gauge anywhere from the back side (cannot check the front side due to lip on the bearing). Then if I need to enlargen the hole perhaps I can do that by carefully using some sandpaper wrapped around my crown race press as that is a 40mm OD tube.