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So I have a new frame which I believe is bb86 and has a Shimano pressfit bb to go in it.
The frame is bare carbon (no metal shell).
With bb30 I’ve always put a bit of grease in the cups before pressing the bearing in, but in the case of carbon it’s suggested you don’t do this. The pressfit bb cup appears to be some kind of plastic composite.
So I either go in ‘dry’ or you can use bearing retainer. I’ve seen mention of loctite 609 / 641 /680 and a park tools one that essentially sounds the same as 680. Some seem to need a primer first so you can still get the stuff off and some need an activator to go off in a vaguely sensible time (quoted as 72 hours).
Am I overthinking it - maybe I should just press it in and see how it goes? If I get creaking the screw together bb adapters look a better idea to me - like the wheels manufacturing one.
I have done a few pressfits,alloy and carbon,and have always used a smear of bearing retainer. Never had any creaks.
Have used a retainer in the past, though only to correct creaking possibly caused by misalignment…install the BB then get the cranks in and torqued before leaving to cure.
Last one I used Morgan Blue Aquaproof and it’s been silent for a couple of years.
Coming back to this I thought I’d try putting the cups in dry and if no creaks then all good. If it creaks then it’s coming out to be refitted with bearing retainer as above.
They pressed in fairly easily with the headset press (dry) - I’d say easier than a bb30 bearing goes in. All seems secure and the cranks are now in and it spins nicely. Bike isn’t quite finished to give it a thorough test yet.