Trek 6.9 bb90 failure?? Anyone experienced this?

Discuss light weight issues concerning road bikes & parts.
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dane476
Posts: 205
Joined: Sat Sep 09, 2006 8:34 pm

by dane476

After fitting bearing and crankset, after around 45/60 hours riding, the integrated cup if the bb90 works itself loose causing movement in the bb and cranks ? Any fix ??

rbrtwyn
Posts: 253
Joined: Thu Dec 09, 2004 1:57 pm

by rbrtwyn

It's probably the bearing that isn't being held tightly in the frame. This is a known issue with BB90. Contact your dealer and ask for V2 BB90 bearings.

by Weenie


em3
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Location: NYC

by em3

Study this thread: viewtopic.php?f=3&t=93006

Not sure what Trek recommends for their press fit cups but plenty of other manufacturers are explicit that Loctite 609 or 641 is needed to install press fit cups. EM3
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Wonderman
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by Wonderman

Iv had no problems with my trek ;)

rbrtwyn
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by rbrtwyn

Just to clarify, there are no cups used with BB90. You just press the bearings into the frame. You need the V2 bearings (which are slightly larger) or Trek has also offered a shim to press the bearings into before pressing them into the frame.

I personally solved it via some Loctite like was mentioned. Apply a little to the OD of the bearing and press it in.

dane476
Posts: 205
Joined: Sat Sep 09, 2006 8:34 pm

by dane476

I live in the uk so both the shim and the v2 bearing should be available from any trek dealer??

durianrider
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by durianrider

email Trek for the best answer IMHO.
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stephen@fibre-lyte
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by stephen@fibre-lyte

I have a feeling that it was a Trek that we repaired recently because the BB bearing had worked loose and the rider hadn't realised before wearing away some of the carbon housing which we had to repair. Judging by threads I've seen this could be a common issue?

Zigmeister
Posts: 921
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

Are you sure it is installed correctly to begin with and spacers on the proper side?

Example, my BB86 in my foil, cranks slipped/bearing came loose. I had put the wavy on the ND side, like my BB30 setup. Well, that is wrong for my S975 Quarq, the wavy goes drive side, no spacers on the left, torque to spec, no problems.

The cranks and torque of the bolt hold the bearings pressed into the frame. At most, they would only creak if they can wiggle slightly while standing on it with some power.

They should never slip/move around the bearing left/right in the frame or cups when spaced, torqued and installed correctly, whatever the instructions say for your cranks/bearing setup. If it does, and everything is correct and it creaks, then loctite 609 will solve that.

But if the bearing diameter is off .1-2 mm, that could cause creaking also, but it wont move side to side still. That is a spacer, torque wavy issue IMHO.

Verify proper install and torque. Then I would take it to the Trek dealer or call them and find out what the deal is.

You never said what cranks you have.

dane476
Posts: 205
Joined: Sat Sep 09, 2006 8:34 pm

by dane476

Pretty sure it was installed correct, been used with shimano cranks according to trek you don't use any spacers :s just the bearing and dust covers??

rbrtwyn
Posts: 253
Joined: Thu Dec 09, 2004 1:57 pm

by rbrtwyn

This is a very common issue with BB90. That's why Trek created the V2 bearing and shim. The tolerance on the BB socket varies since the frame is carbon. Some are good and some need the above fix.

Zigmeister
Posts: 921
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

dane476 wrote:Pretty sure it was installed correct, been used with shimano cranks according to trek you don't use any spacers :s just the bearing and dust covers??

If installed correctly, then get in touch with the Trek dealer and ask about the v2 bearings people have mentioned.

Even .1-.2mm can make a big difference in how snug/tight the fit is. You still might need loctite 609 to get it real tight/secure.

Good luck.

by Weenie


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aratchet
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Joined: Mon Nov 23, 2009 11:52 am

by aratchet

Something to think about before you Loctite bearings,adaptors or sleeves into a carbon frame is that the standard way for disassembly of most Loctite bearing and stud mounts is applying heat. In the case of Loctite 609 and 641 250º C. See the TDS :

http://media.midwayusa.com/pdf/instruct ... te_609.pdf" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Do you want to heat your carbon frame up to that temp? I wouldn't on mine. Many manufacturers tell you not leave your frame in a closed car on a hot day! Just like your dog, it may die.

I was skeptical when Trek brought out the all carbon BB and am even more so now that I see they have special oversize bearings and shims for out of tolerance bottom bracket moulding.

The TDS also says that Loctite 609/641 is not recommended on thermoplastics. The fact that it may be recommended by various manufacturers leads me to assume that these designs are having service issues. I work in the automotive industry and most of the gap filling/sleeve retaining Loctite type products require heat and or quite a bit of force to take them apart. Pounding or rigging up an elaborate puller on a lightweight bottom bracket with little material to begin with seems like asking for trouble.

However, you may be left with little choice but to use these products so you have a useable crank/bearing assembly. But it may make for a trashed frame when it comes time to replace the bearings.

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