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Old 02-26-10, 01:36 PM   #1
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New SRAM Rival bottom bracket scraping noise (video), ideas?

I'm preparing to install SRAM Rival group on new bike. This is my second Rival crankset. The first, on my other bike, installed with no problems. BB quiet as a mouse.

As you'll see in the video, when spun there is a scraping noise. Same noise also present when crankset fully installed and torqued to spec.

I've wiped and re-greased the bearing surfaces, there was a bit of grit present. This is a brand new group.

Also: The manual states there are two bearing seals -- one for each side. The drive side one is obviously present. The non-drive side one doesn't appear to be there (see pic). I received the bb as you see it in the pics.

I have the see-through plastic center piece (with gxp logo) installed so the fatter lip is mated with the drive side cup.

Any ideas on how I can troubleshoot this scraping noise? Thanks.




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Old 02-26-10, 02:33 PM   #2
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Probably a stupid question, but could the sound be coming from the crank instead of the BB? Perhaps a chainring is loose or not seated properly.

I assume that you have tried to feel for vibrations with one hand while turning the cranks slowly to try to isolating the exact location of the noise. My next step would be to use your other Rival group to your advantage: Try using the old Rival crank on this BB to see if the sound is still there. If so, then try using the BB from your other bike. It's easy enough to do and you'll be able to quickly find out where the failure is.
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Old 02-26-10, 07:04 PM   #3
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Probably a stupid question, but could the sound be coming from the crank instead of the BB? Perhaps a chainring is loose or not seated properly.

I assume that you have tried to feel for vibrations with one hand while turning the cranks slowly to try to isolating the exact location of the noise. My next step would be to use your other Rival group to your advantage: Try using the old Rival crank on this BB to see if the sound is still there. If so, then try using the BB from your other bike. It's easy enough to do and you'll be able to quickly find out where the failure is.
Used the old rival crank and noise still there so looks like bb. Took it apart and rough/scratchy/gravelly sound appears to be coming from bearing in non-drive side up.
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Old 02-26-10, 07:21 PM   #4
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the non drive seal is present
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Old 02-26-10, 09:04 PM   #5
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should have bought a shimano ultegra dude, this is what happens when you go SRAM, just kidding, hmmmmmm if it were the bearings would you hear something crunching and stuff? This might be a faulty crankset, looks like you greased what needed to be and you torqued to spec. IDK what would be the problem. What about brushings?
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Old 02-27-10, 12:00 AM   #6
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I also switched out BBs -- taking the same BB from my other bike -- and pretty much the same sound was present...until I tightened down to torque spec and now it sounds much better, however, still not as smooth as the spin on my Specialized Allez. The bike I'm building up is a Blue T-14.
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Old 02-27-10, 12:00 AM   #7
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the non drive seal is present
thanks, I noticed this when it popped out during removal on my road bike ;-)
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Old 02-27-10, 02:00 AM   #8
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How do you know the bb shell faces are parallel? Is that a carbon shell?
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Old 02-27-10, 05:28 AM   #9
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How do you know the bb shell faces are parallel? Is that a carbon shell?
Additionally if his bb and crank do not make this type of sound on his other bike you can start looking at bb shell problems, e.g within tolerance/faced etc.
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Old 02-27-10, 01:04 PM   #10
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Additionally if his bb and crank do not make this type of sound on his other bike you can start looking at bb shell problems, e.g within tolerance/faced etc.
I would agree.

Here's a link to the bike. The only carbon parts are the seat stays and chain stays.

http://www.bikesportmichigan.com/bik...lue-comp.shtml
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Old 02-27-10, 01:27 PM   #11
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I would agree.

Here's a link to the bike. The only carbon parts are the seat stays and chain stays.

http://www.bikesportmichigan.com/bik...lue-comp.shtml
I'm thinking the OP should just remove the seals again and *thoroughly* clean the contact surfaces. It doesn't jive with me that a bb shell problem will cause it to make a noise like that.
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Old 02-27-10, 01:28 PM   #12
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I'm thinking the OP should just remove the seals again and *thoroughly* clean the contact surfaces. It doesn't jive with me that a bb shell problem will cause it to make a noise like that.
thanks. I did this and it's much smoother sounding now. cheers
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