# Carbon Madone BB90 Bearing Cups - To Grease or Not to Grease... That is the question?



## Trek Road Dogg (Jan 30, 2012)

Hi all,

I did read through a lot of posts trying to see if I could locate this topic, but I had no luck on anything this specific.

There is a Trek tech doc with Service Information on the 2010 Madone which includes a section that states to "apply a liberal coat of grease" to the bearing cups when installing the bearings. This is generally good enough for me and I would tend trust the manufacturer.

Yet I've been told by several LBS and even Trek specific shops to not grease the cups on the Madones with carbon frames as this adds to teh bearings slipping over time.

Yet even another group of folks in between stating the grease doesn't hurt, but is not necessary.

What are the folks here doing when it comes to setting up the BB90 bearings in carbon frame Madones?

On a 2012, I've had no issues with the original bearings put in the bike during the original assembly, but I had to just pull and replace the bearings for internal wiring purposes (Di2) and wanted to make sure I have the best chance of keeping the bottom end squeak free. 


Thanks


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## tihsepa (Nov 27, 2008)

Trek Road Dogg said:


> Hi all,
> 
> I did read through a lot of posts trying to see if I could locate this topic, but I had no luck on anything this specific.
> 
> ...


I grease everything on mine. Never had an issue. 

This is just how I chose to do it.


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## Trek Road Dogg (Jan 30, 2012)

Thanks for sharing your experience. Almost every video I've watched also uses grease in the cup. But still hard to not trust a couple of great shop wrenches that I've seen in action and special in Treks. 

Leaning towards the Trek Service Information doc and might go with grease.


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## Roland44 (Mar 21, 2013)

tihsepa said:


> I grease everything on mine. Never had an issue.
> 
> This is just how I chose to do it.


Same here. I grease everything as well and never had a problem...


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## cxwrench (Nov 9, 2004)

EVERY Trek that has BB90/95 comes from them w/ grease. I've always greased mine.


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## Trek Road Dogg (Jan 30, 2012)

Thanks everyone. My wife's new Madone also came with greased bearings for the BB. And since I had no issues I think it would be wise to follow the doctor's orders. 

Thanks


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## Lelandjt (Sep 11, 2008)

Loc-tite bearing retaining compound is the best thing to use here and improves your odds of staying creak-free. I originally stumbled on it when suspension bikes said to use it for pressing in fresh bearings. Now I use it for any bearing being placed or pressed into something. It keeps things snug and creak-free but also prevents corrosion and allows them to be removed.
If you don't have green Loc-tite the question of whether to grease a press-fit has been argued over since before I became a mechanic. It used to be headset races and cups and BMX BB cups. The argument for was to prevent corrosion freezing the parts together and maybe grease could silence creaking. The argument against was that a press-fit relies on friction and in other industries they aren't usually greased.


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## cxwrench (Nov 9, 2004)

Lelandjt said:


> Loc-tite bearing retaining compound is the best thing to use here and improves your odds of staying creak-free. I originally stumbled on it when suspension bikes said to use it for pressing in fresh bearings. Now I use it for any bearing being placed or pressed into something. It keeps things snug and creak-free but also prevents corrosion and allows them to be removed.
> If you don't have green Loc-tite the question of whether to grease a press-fit has been argued over since before I became a mechanic. It used to be headset races and cups and BMX BB cups. The argument for was to prevent corrosion freezing the parts together and maybe grease could silence creaking. The argument against was that a press-fit relies on friction and in other industries they aren't usually greased.


You do realize we're talking about Trek BB90/95 bottom brackets here and not 'normal' PF bb, right?


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## Lelandjt (Sep 11, 2008)

Yeah. I've changed the bearings on a Trek Madone. That shop didn't have green loctite so I used grease.


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## cxwrench (Nov 9, 2004)

*Carbon Madone BB90 Bearing Cups - To Grease or Not to Grease... That is the q...*

Just to be sure I'm getting this straight, the sum total of your Trek BB90 experience is a single bike? And from that you're advising the OP to ignore the advice provided by Trek and to use Loctite?


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## Trek Road Dogg (Jan 30, 2012)

Since I had some time to think this one over I went ahead and order a pair of ceramic bearings. So I hope overall I end up with a positive experience. 

I have two types of grease at home, Park Polyalube 1000 PPL-1 and Motorex White Grease for bikes. Either one better for this job? Or 6 of one and 1/2 a dozen of the other?


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## tihsepa (Nov 27, 2008)

Either grease will be fine. The ceramic bearings were a waste of money.


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## Trek Road Dogg (Jan 30, 2012)

tihsepa said:


> Either grease will be fine. The ceramic bearings were a waste of money.


Not really expecting to pick up 3 mph or anything like that. And did not splurge on expensive bearings. But rather than put the old ones back in, there should be some benefit to new (even if only the 8 gram difference) 

Thanks for the tip on the grease. That's about what I thought. Not much will be left once the bearings are fitted. Then it become what color ooz do you like, white or green!


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## aclinjury (Sep 12, 2011)

Can somebody explain to me the purpose of using grease between 2 parts that 

1) are meant to stick together via friction, i.e., no freeplay once pressed together
2) are press together so tight that the grease are pressed out

I'm trying to understand the main purpose of using grease in this scenario


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## cxwrench (Nov 9, 2004)

aclinjury said:


> Can somebody explain to me the purpose of using grease between 2 parts that
> 
> 1) are meant to stick together via friction, i.e., no freeplay once pressed together
> 2) are press together so tight that the grease are pressed out
> ...


Do you put grease on threads? Think about this and your question, then reply.


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## aclinjury (Sep 12, 2011)

cxwrench said:


> Do you put grease on threads? Think about this and your question, then reply.


I actually thought about it before I posted. Thread has room for the grease to act; eg, there's freeplay between the threads and bolt. Also the grease help the bolt to screw in easier. Aren't these pressfit system involve pressing a hard and smooth plastic cup into a smooth carbon bottom bracket? Maybe the grease is to help them slide in easier? maybe that's why a lot complain about pressfit creaking. You don't hear much about BSA creaking


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## cxwrench (Nov 9, 2004)

aclinjury said:


> I actually thought about it before I posted. Thread has room for the grease to act; eg, there's freeplay between the threads and bolt. Also the grease help the bolt to screw in easier. Aren't these pressfit system involve pressing a hard and smooth plastic cup into a smooth carbon bottom bracket? Maybe the grease is to help them slide in easier? maybe that's why a lot complain about pressfit creaking. *You don't hear much about BSA creaking*


Sounds like you've never worked in a bike shop. Threaded bb have always had problems w/ noise. I've worked on bikes that have clicked and creaked for as long as I've been a mechanic. Ti frames are the most prone to it.


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## Lelandjt (Sep 11, 2008)

cxwrench said:


> Do you put grease on threads? Think about this and your question, then reply.


I'd have expected you to understand the different requirements of press-fit and threads. Are you not familiar with the 30+ year old quandry of whether or not to grease press fits and the arguments each way? And my experience of changing press-fit cartridge bearings goes way beyond one bike. The reason I've mentioned Loctite bearing retaining compound in a couple threads is the engineers and chemists at that company have tackled this dillema and provided their best solution. General consensus is it works better than grease or no grease.


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## aclinjury (Sep 12, 2011)

cxwrench said:


> Sounds like you've never worked in a bike shop. Threaded bb have always had problems w/ noise. I've worked on bikes that have clicked and creaked for as long as I've been a mechanic. Ti frames are the most prone to it.


Well you're correct in saying I've never worked in a bikeshop! True.

yes I've seen threaded bb creak too, especially on mountain bikes, but often times the creaking come from damaged cups/ball bearings too. Hard for me to pinpoint the creak to the thread/cups interaction, or damage bearings.

But I'll trust you when you say threaded bb creak. 

But going by RBR posts here, there is a disportionately more posts about press-fit bb creaking than there are about threaded bb creaking. This little stats, while not scientific, does say something about press-fit bb.

However, I still don't understand the logic of using grease between 2 components that are meant to be press-fitted together with the force holding them together arising from the frictional force between them pressed in tightly. So what is the purpose of the grease when used in such manner? Is it to ease the press-fitting process? Is it to keep the cup and bb tight once pressed in? Is it to prevent the creaking of the cup/bb interface?

If the cup/bb interface was metal to metal contact, then I can see the logic of using grease to ease them in. But the interface in this is case is plastic to carbon fiber. Guess I just don't see the sound logic of using grease here.


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## aclinjury (Sep 12, 2011)

Ok so I took some initiative to understand the basic of grease.

Grease (lubricant) - Wikipedia, the free encyclopedia

The above link is only basic stuff. And I ain't no expert.

If I had to guess why Trek (or any manufacturer) recommend the use of grease is:

1) to ease the press-fitting process
2) to prevent the freezing of the joint

Lubrication also helps in reducing the shear stress of the interface by allowing the constituents of the interface to "slide" along each other, rather than "stick and rip apart"? But doesn't the sliding will also cause the creaking too? So could the thinking be that..

"we rather that the interface slide and creak but reducing shear force,.. then to not creak at all but potentially rip apart"?? 
(me guessing, of course)

Just an educated guess from a non-expert. Maybe an expert want to chime in and point out the reason why Trek would recommend using grease, and the pros and cons of using grease, and/or if using grease is even a sound logic to begin with.


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