# How snug are BB90 bearings supposed to be?



## thisisthebeave (Aug 30, 2015)

I was reinstalling my crankset and my NDS bearing just fell out. I'm sure the edge of the crank spindle pushed it out, but shouldn't it be tighter than that?

I tapped it back in and it seems snug now, but isn't it odd to have fallen out so easily? 

If it matters... When I got my Stages power meter installed (would have done it myself but a bolt stripped) the mechanic said my "bottom bracket was loose" so they "glued it back together".


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## bobf (Apr 3, 2015)

That does sound loose, but if your BB has no play and makes no clicking/creaking noise I think you are ok. Gluing sounds a little drastic to me. If it works it will keep your bearings from moving and making noise. But what happens if you ever need to change them out?

FWIW, the BB on my Domane has developed a noise, and I'm going to try a fix I found here:

http://www.vcrcbike.com/v/vspfiles/webfiles/BBinstall.pdf

The idea is to put a thin smear of rim cement inside the frame, then let it dry for 12 hours before installing the bearings. The purpose of the cement is to tighten the fit around the bearings, not to glue them in. Shall see if it works that way in practice.


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## cxwrench (Nov 9, 2004)

Both of you...seriously. There are bearings available from Trek. They're called 'V2'. They're .1mm larger diameter than standard. Glue is not the solution. If the shell ever gets loose w/ V2 bearings it needs to be sent back to Trek and they can fix it.


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## ericm979 (Jun 26, 2005)

I'd go with Loctite 641, with the special "activator" primer. The VCRC document explains this. They say to use 609 or 638 but 638 is high strength while 641 is medium strength designed for parts that need to be taken apart. When Loctite calls something high strength you usually need to heat the parts to destroy the bond.


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## goodboyr (Apr 19, 2006)

Lack of trek frame knowledge leads to a fascinating array of crappy advice. Listen to cx.....


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## cxwrench (Nov 9, 2004)

thisisthebeave said:


> the mechanic said my "bottom bracket was loose" so they "glued it back together".





bobf said:


> The idea is to put a thin smear of rim cement inside the frame, then let it dry for 12 hours before installing the bearings. The purpose of the cement is to tighten the fit around the bearings, not to glue them in. Shall see if it works that way in practice.





ericm979 said:


> I'd go with Loctite 641, with the special "activator" primer. The VCRC document explains this. They say to use 609 or 638 but 638 is high strength while 641 is medium strength designed for parts that need to be taken apart. When Loctite calls something high strength you usually need to heat the parts to destroy the bond.


There is the correct way to solve this issue which is V2 oversize bearings available through any Trek dealer. Then there is the wrong way...see all posts above. Do NOT use any adhesive to shim/bond bearings into a Trek frame. Get the oversize bearing and if that doesn't solve the problem the frame is going to need a trip to Wisconsin to be repaired.


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## Tachycardic (Mar 31, 2013)

Or use bubble gum, preferably chewed first, if you don't want to wait.


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## thisisthebeave (Aug 30, 2015)

Can you get the V2 bearings online or should my LBS have them in stock?


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## cxwrench (Nov 9, 2004)

thisisthebeave said:


> I was reinstalling my crankset and my NDS bearing just fell out. I'm sure the edge of the crank spindle pushed it out, but shouldn't it be tighter than that?
> 
> I tapped it back in and it seems snug now, but isn't it odd to have fallen out so easily?
> 
> If it matters... When I got my Stages power meter installed (would have done it myself but a bolt stripped) the mechanic said my "bottom bracket was loose" so they "glued it back together".





bobf said:


> That does sound loose, but if your BB has no play and makes no clicking/creaking noise I think you are ok. Gluing sounds a little drastic to me. If it works it will keep your bearings from moving and making noise. But what happens if you ever need to change them out?
> 
> FWIW, the BB on my Domane has developed a noise, and I'm going to try a fix I found here:
> 
> ...





ericm979 said:


> I'd go with Loctite 641, with the special "activator" primer. The VCRC document explains this. They say to use 609 or 638 but 638 is high strength while 641 is medium strength designed for parts that need to be taken apart. When Loctite calls something high strength you usually need to heat the parts to destroy the bond.





thisisthebeave said:


> Can you get the V2 bearings online or should my LBS have them in stock?


If your LBS is a Trek dealer odds are good they'll have them. They are, as I mentioned previously, available through Trek. Yes, you can probably also order them online.


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## thisisthebeave (Aug 30, 2015)

Do I definitely need the V2 bearings? I'm sure it was the edge of my crank that knocked it out? I'm not sure how much force it should take to knock the bearings out.


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## thisisthebeave (Aug 30, 2015)

cxwrench said:


> There is the correct way to solve this issue which is V2 oversize bearings available through any Trek dealer. Then there is the wrong way...see all posts above. Do NOT use any adhesive to shim/bond bearings into a Trek frame. Get the oversize bearing and if that doesn't solve the problem the frame is going to need a trip to Wisconsin to be repaired.


Thinking back on it, I'm sure the edge of the crank caught the edge of the bearing and pushed it out when I was reinstalling the crank. Should it take a lot of force to get the bearing out?

Just trying to figure out if I need the V2 bearings or not. I picked them up but haven't installed yet. The paper that came with them makes it sound scary bad to use them if you don't NEED them.


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## cxwrench (Nov 9, 2004)

thisisthebeave said:


> Thinking back on it, I'm sure the edge of the crank caught the edge of the bearing and pushed it out when I was reinstalling the crank. Should it take a lot of force to get the bearing out?
> 
> Just trying to figure out if I need the V2 bearings or not. I picked them up but haven't installed yet. The paper that came with them makes it sound scary bad to use them if you don't NEED them.


The ONLY proper way to install or remove them is with a bearing press. It should take some oooomph to get them in or out but should feel smooth. One of the biggest problems people encounter is getting them in straight. If they go in the least bit crooked you can do damage to the frame. I have seen them pop out when pushing a crank axle through the bottom bracket, and usually this is an indication they are 'loose' and the V2 bearing is needed. That said, I have no idea how hard you were pushing/hitting the crank to get it through the bearings. If you were just pushing it by hand and the NDS bearing popped out I'd say yes, install a V2. If you were smacking the crank w/ your hand pretty hard or using a mallet...the normal bearing is probably ok. Kinda vague, but it's the best I can do over the interwebs. If you can pull the bearing out by using your fingers or even get it to rock a little in the frame, you need the V2. 

Yes, if you install an oversize bearing into a bottom bracket that isn't loose you'll cause problems like possibly cracking the frame. While not difficult it's a job best left to someone w/ a bunch of experience and the proper tools. It can be done w/ a Park headset press and the proper adaptors, I prefer to use the Enduro bottom bracket bearing press that is meant specifically for 24mm axle cranks. 

Also, the 'edge of the crank' isn't the proper way to describe what happened, it was actually the part of the crank axle that steps down from 24mm to 22mm that cause the bearing to get pushed out.


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## thisisthebeave (Aug 30, 2015)

cxwrench said:


> The ONLY proper way to install or remove them is with a bearing press. It should take some oooomph to get them in or out but should feel smooth. One of the biggest problems people encounter is getting them in straight. If they go in the least bit crooked you can do damage to the frame. I have seen them pop out when pushing a crank axle through the bottom bracket, and usually this is an indication they are 'loose' and the V2 bearing is needed. That said, I have no idea how hard you were pushing/hitting the crank to get it through the bearings. If you were just pushing it by hand and the NDS bearing popped out I'd say yes, install a V2. If you were smacking the crank w/ your hand pretty hard or using a mallet...the normal bearing is probably ok. Kinda vague, but it's the best I can do over the interwebs. If you can pull the bearing out by using your fingers or even get it to rock a little in the frame, you need the V2.
> 
> Yes, if you install an oversize bearing into a bottom bracket that isn't loose you'll cause problems like possibly cracking the frame. While not difficult it's a job best left to someone w/ a bunch of experience and the proper tools. It can be done w/ a Park headset press and the proper adaptors, I prefer to use the Enduro bottom bracket bearing press that is meant specifically for 24mm axle cranks.
> 
> Also, the 'edge of the crank' isn't the proper way to describe what happened, it was actually the part of the crank axle that steps down from 24mm to 22mm that cause the bearing to get pushed out.


I hit the crank with my hand but not that hard. That's really my only indication anything is wrong. There's no creaking or anything. You think V1 bearings if that's the case?


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