oh boy... please accept my appologies in advance PF30 BB shell with Campy Ultra-Torque

Discuss light weight issues concerning road bikes & parts.
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ultimobici
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by ultimobici

spookyload wrote:
ultimobici wrote:
Sat Aug 11, 2018 7:38 pm
spookyload wrote:I installed mine with grease. Not a peep. I was told loctite is used if to creaks after you try grease first
Never ever use grease. 609 is a compound for fitting cylindrical items together. It fills the gaps and sets to prevent movement. All grease does is helps the cups move.


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I’ve been using it on frames since 2002 without creaks or issues. 609 only helps if there is imperfections in the surface. It simply fills the gaps to correct that. Manufacturers are split on its use. Some actually void the warranty if you use it on their frames during assembly. Seatposts are cylindrical, do you use it when you insert them? I doubt it. Bar stem interfaces are cylindrical do you use it there.? No, you use carbon paste.
I’ve not heard of any manufacturer prohibiting 609 bring used on their frames. Using it with nylon cups such as those Sram use on their PF30 cups isn’t advisable as the nylon doesn’t take too kindly to the 609.

I suspect you’ve just been lucky.


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GothicCastle
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Joined: Mon Jul 04, 2016 1:52 am

by GothicCastle

Catagory6 wrote:
Sat Aug 11, 2018 7:23 pm
as i've been doing more searching, i've seen people say using grease runs the risk of softening the CF
I’ve seen people try to drink a whole gallon of milk at once. Lots of stupid people on the web.

by Weenie


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Calnago
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by Calnago

Grease should never be used in an interference pressfit application. You do not want any movement in an interference fit, and that’s exactly what grease will facilitate, especially if the fit is less than perfect in the first place (enter carbon bicycle bottom bracket shells). All it does is mask the creaking for a while by allowing the movement to be relatively silent.
Creaking is the result of movement between the surfaces. To stop it, use a retaining compound plus primer. The primer is necessary for inactive substrates such as carbon. I have never heard of a manufacturer who voids a warranty for using a retaining compound to stop a creaking bottom bracket but it’s easy to list manufacturers who recommend it.

As for grease being a problem for carbon fiber in general, I think if that were a problem then the vast majority of manufacturers who just drop headset bearings into a molded carbon headtube, or use a carbon steertube with a molded molded crown race would have a real problem since grease surrounds all those parts.

The only time I’ve ever heard of anyone saying to avoid grease around carbon was in this thread about a creaking Madone BB. And the BB90 Bottom bracket is not an interference pressfit, but a slipfit. It uses grease.

Here is a link to that thread should you want to see it in its entirety...
https://weightweenies.starbike.com/foru ... 3&t=147889
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