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Old 07-11-12, 04:04 AM   #1
GMember
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Experience with Trek BB90?

Hey guys,

I've got a brand new 2012 Madone 5.2 with BB90 and Ultegra compact cranks (bike is fully stock). Less than 1k miles ridden so far...

Problem is, I've got the slightest play in my BB. Gripping the crank on both sides I can knock it back and forth just enough to feel it.

I've taken the cranks off, removed and reinstalled the bearing cartridges, tightened down the compression cap a little more than it should (haha) and still have play.

Is there supposed to be some kind of spacer between the bearing dust seal and the left crank arm? It doesn't seem like there should be, but it's the only thing I can think of.

If anyone who knows about Trek BB90s could give me some insight, that would be awesome
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Old 07-11-12, 04:57 AM   #2
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Only thing I can tell you is that I have two of them and neither has play in the crank. I would take it back to the shop and have them look at it.
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Old 07-11-12, 06:20 AM   #3
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Should be no play if you have both seals in there. Sometimes you have to torque down the compression cap more than specified to seat the cranks and bearing seals, but you can usually back it off to spec. Your bearings may be moving around in the seat, this is a frame failure and you'll need to deal with Trek for a new frame.

Luck

- Joel
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Old 07-11-12, 06:22 AM   #4
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This is a known issue and Trek will supply, under warranty, slightly oversize bearings. That should fix it. Get thee to thy dealer.
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Old 07-11-12, 06:28 AM   #5
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Interesting to note about the oversize bearings. Trek Australia doesn't go for that option

- Joel
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Old 07-11-12, 09:35 AM   #6
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This is a known issue and Trek will supply, under warranty, slightly oversize bearings. That should fix it. Get thee to thy dealer.

Ahh... I was wondering about that. When I took out the bearing cartridges it felt almost loose in the frame. They should be a tight press fit right?
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Old 07-11-12, 10:19 AM   #7
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Ahh... I was wondering about that. When I took out the bearing cartridges it felt almost loose in the frame. They should be a tight press fit right?
BB90 is slip fit, meaning you can remove and install the bearings by hand, without tools. However, the fit has to be within tolerances. Press fit is a pressed-in bearing that requires a tool to press the bearing in. It sounds like Trek has built some frames that are slightly out of spec and their solution is to supply a slightly different size "BB90" bearing assembly, maybe they should call those BB90 with an asterisk.
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Old 07-11-12, 05:55 PM   #8
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This is a known issue and Trek will supply, under warranty, slightly oversize bearings. That should fix it. Get thee to thy dealer.
correct
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Old 07-11-12, 06:44 PM   #9
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correct
What is a slightly oversized bearing?
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Old 07-11-12, 06:57 PM   #10
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trek puts a sleeve around the "correct" bearing, at least it looks that way. either way it tightens up the fit. you can also use retaining compound for loose fits
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Old 07-11-12, 08:31 PM   #11
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correct
Yep. Preload is not the answer, the bearing needs to be larger. Trek has a couple flavors, one of which has a 0.05 sleeve over the outside (I put these in the freezer for a couple minutes just prior to installation, after having the sleeve crumple on one of them). The other is built with the outer race slightly larger in its own right.
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Old 06-05-13, 11:05 AM   #12
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Found this thread on a Google search. Couple of questions for those in the know. First, do these bearings have to be serviced or are they good to go "forever"? Should/could I remove the outer seal and regrease the bearings, or is that not necessary? Also, I have well over 10k miles on the bike, and have never had a problem with the BB, so is it safe to assume I have the "standard" non-oversized BB, or did Trek manufacture bikes out of the factory with the oversized ones? In other words, if I'm not having a problem, then must I have the standard BB? Thanks!
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Old 06-05-13, 06:36 PM   #13
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i do not service cartridge bearings if you are paying me to punch the bb out i might as well put new bearings in
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