Help, press fit BB and headset into carbon frame . Grease ?

So i’m about build a frame up and need to fit a press fit BB. Shimano XT version which is a plastic shell and also a Hope zero stack headset. Are supposed to apply grease to them or just press them in?
I have grease and carbon paste to hand.

A light skim of grease wont do any harm, I use it on the above on my carbon bikes and I haven’t died yet.

I’d probably use carbon assembly paste

I used carbon grip paste, worked well. Some types of grease (not all) supposedly can cause issued in carbon fibre.

I think if your grease has solvents in it, then I’d pause for thought if smearing it on clearcoat finish . If it’s bare carbon exposed weave, then probably not, I’d imagine the fibres would be pretty immune. I’s still think that the rule of “if you want it to be removed at some point, grease it” applies, and I’d be putting a smear of it on the BB and headset.

. I’s still think that the rule of “if you want it to be removed at some point, grease it” applies, and I’d be putting a smear of it on the BB and headset.

Doesn’t that assume that there’s a potential metal to metal reaction that’s not going to happen with carbon fibre – normally the issue with metal and carbon is bonding the former to the latter rather than the converse. And carbon frames have metal BB threads…

carbon frames have metal BB threads

The OP has a carbon fibre bike, and a press-fit BB. I only have experience with two bikes in this combination but they had care carbon BB shells that were bare CF weave on the inside surface.

There’s no way I’d be using carbon assembly paste – you’re putting tiny particles of grit in close procimity to bearings.

I’ve read horror stories about grease causing carbon to delaminate, but I’ve always put a bit of grease on headset/BB bearings (but significantly less than I’d slap on in an alu frame), and no steerers or BB shells have collapsed on me yet…

I always put a smear of grease between them and never had a reaction with the carbon. I have also had to gently tap out a bottom headset race with a bit of wood and a mallet from a frame we bought second hand that obviously hadn’t been greased hoping that the carbon wasn’t damaged. Never used carbon assembly paste on them as we were advised not to by a team mechanic.

I used Bell marine grease, sold as carbon friendly.

I also contacted YT about my carbon Jeffsy and they said use grease on the bb.

I use a little on the direct to carbon headset races too.👍

finbar

There’s no way I’d be using carbon assembly paste – you’re putting tiny particles of grit in close procimity to bearings.

Yep. And under no circumstances ride the bike outside, and certainly not on mountains

Cheers guys, thanks for your opinions.The grease i was look to use was Mobil Mobilgrease XHP 222 High Performance Grease with just a thin smear of it.
My main thought was with the BB being Shimano’s XT nylon jobbie does it need a friction fit rather than grease to stop any creaking.

Mobil Mobilgrease XHP 222

Pretty sure that great is ok on carbon,a Google should confirm..

Personally, I’d apoly a bit of grease on the Shimano press fit.