Press Fit BB - To Grease or Not?

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 crayefish 18 Mar 2021

So, currently rebuilding my XC bike for a much needed overhaul.  The press fit BB is knackered, so I have a new one to fit it today (I have a new Shimano XT BB).  My mate with the proper tools has unfortunately gone AWOL, so I'll be doing it myself with the hammer/punch and threaded rod/large washers approach.

Question is... for a carbon frame and plastic bearing shells, should I use grease or press fit dry?  The internet's bike forums are largely spilt on the matter (of course), leaning towards using grease, though Shimano seem to imply to fit it dry.  What's UKC's opinion (ideally based on actual experience)?

I have carbon safe grease (muc-off), before anyone chips in with epoxy melting stories. 

 Yanis Nayu 18 Mar 2021
In reply to crayefish:

I think park tools do some rather expensive stuff to apply in 2 parts for such scenarios. 

 mike123 18 Mar 2021
In reply to crayefish: I’ve always used a very thin smear of carbon assembly grease , nor sure what is is but it’s very light . Also not wanting to tell my granny how to roll a fat one , but push fitting to carbon with out a bearing press ? What could possibly go wrong ? 
edit : was going to add , where are you ? Bit far  from the Netherlands to my kitchen . Plus mine is at my numb nuts mates house anyway 

Post edited at 09:38
OP crayefish 18 Mar 2021
In reply to mike123:

Funnily enough, carbon paste seems to be widely regarded as a no-no... can kind of see why with the fine grit in there.  Shows that there are many ways to skin a cat!

OP crayefish 18 Mar 2021
In reply to mike123:

Question solved!  Just knocked out the old bearings with my home made Park Tool jobbie (steel tube with the end sawn and split 4 ways), and it seems Cube used grease when fitting the original...

 mike123 18 Mar 2021
In reply to crayefish: useful to know . My mate “bike shop bri “ always uses it .  

Edit : might be why his bikes always fall apart

Post edited at 12:12
 Mr Messy 23 Mar 2021
In reply to crayefish:

Probably missed the boat on this but there is some new thinking of using expanding loctite to eliminate any imperfections gaps and so stop rocking. Sorry can not remember which one.

OP crayefish 23 Mar 2021
In reply to Mr Messy:

Yeah, already fitted with grease using some home-made tools, and so far no creaks   Indeed, knew about the loctite method, but GMBN state that a surface prep compound (can't recall the correct term) should be used as well to prevent it being so stuck that you can't get it out later.  I didn't have any of this, so was basically left between dry and grease.


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