THM bottom bracket noisy - bearing drag? Video provided.

Discuss light weight issues concerning road bikes & parts.
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Rippin
Posts: 609
Joined: Thu Feb 19, 2004 9:58 am

by Rippin

Hi all,

I've been riding the THM bb (non-ceramic) and crank set up for a bit now. I've recently removed the chain to check out the noise from the BB. I seem to remember that a similar noise was there when I initially installed the crankset, but I chalked that up to "new" bearings and thought it would wear in and the noise would be reduced. Standard english threaded version of THM's BB in a Look 586 frame, installed with proper torque, has not backed out. Clavicula crankset was installed as per THM's instructions. BB was not faced.

Here's a video of the bearing noise:
http://www.youtube.com/watch?v=DV5KlvRhXKQ&feature=plcp

You will have to turn up your sound to hear it properly.

My concern is that there is too much drag. What are your thoughts? Normal for THM bearings?
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sedluk
Posts: 409
Joined: Mon Sep 07, 2009 3:10 am

by sedluk

When you install the crank you need to leave just enough play so that the bearings can spin freely. You basically tighten the crank until there is some resistance and then back off so there is no resistant. What you have here is not a problem with your BB but a problem with your crank.

by Weenie


Rippin
Posts: 609
Joined: Thu Feb 19, 2004 9:58 am

by Rippin

Thanks for the reply but I'm not quite following what you are suggesting.
Where are you referring to the tightening?
The preload cap? The non-drive side pinch bolts?
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pawnii
Posts: 359
Joined: Sun Sep 27, 2009 9:54 am
Location: Australia

by pawnii

Preload cap is too tight or your bearing isn't sitting in the BB perfectly.

If you back off the Preload cap and you get play in the crank it's probably because the aluminium bearing seats on the axle is worn. This is a common problem with the Clavicula.
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sedluk
Posts: 409
Joined: Mon Sep 07, 2009 3:10 am

by sedluk

I was suggesting that your preload cap was too tight before you tightened the pinch bolts.

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