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cyclist
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Hey All,

I have a recurring problem with the BB on my MXL. On the drive side, the BB lock ring keeps loosening and backing out. I thought I had the problem fixed by readjusting the whole BB, but this didn't help. It backs out a lot on just a short (30 miles) ride.

Anybody out there have any experience/suggestions on fixing this? (besides lock-tite, which my boss says will only extend the time between adjustments, but not fix the problem.) Am I overlooking something?

Also, the lock ring backs out and the crank (and rings) backs out enough for me to lose shifting to the big ring altogether.

TIA.
 

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2,655 Posts
Drive side- Strange

Given that it's right hand threaded.

You don't say what sort of BB but it sounds like, it's a loose ball, fixed and rotating cup design with lock ring.

First off, it sounds like you have cups reversed, assuming you have a fixed and adjustable cup BB. The fixed cup should be on the drive side. The adjustable cup on the non-drive side.

Next point applies to either loose ball or sealed bearing BB's

Was the frame ever prepped, ie BB shell faced? If not, the lockring may not be flush against the BB for its complete diameter, thereby allowing it to loosen.

As for loctite, I wouldn't bother but you might want to try using one wrap of teflon plumber's tape on the adjustable cup, after its been threaded into the BB shell. This might help with lockring retention and not leave a problem after when you want to disassemble the BB.

I think your BB needs facing but is this a new frame or one you've owned for a while and using a different BB?
 

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aka Zonic Man
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593 Posts
This is common on italian threaded bottom brackets, this loosening.

I'd remove the BB, clean and chase the threads with a good BB tool, then re-install (properly) with the proper torque (25 ft/pounds) and some blue threadlock (loctite) on the threads.
 

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The web is a MUT
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1,373 Posts
prep work

The former shop owner where I got my ML said he always took his time with these bottom brackets doing a carefull and accurate facing and assembly, and rarely did any ever come back for adjustment.

I used to have a Raleigh Comp many years ago that always had the bottom bracket loosen up, a shop in Seattle finally torqued it down hard enough that I never had another problem with it.
 

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Common?

It does happen but generally if it's going to happen, it will be the non-drive side. If I read it right, he's having a problem on the drive side, the side which gets tightened under normal pedaling which leads me to my comment about the facing rather than the threads. The cup's backing out as the lockring's not flush against the shell, allowing the cup to work its way out. Well, that's the theory at least.

In truth, I've had Italian threaded cycles for 30+ years and only had the BB loosen once. Non-drive side on a Campag C-Record (loose balls) BB as I didn't tighten down the lock ring with sufficient torque after repacking the BB. Long walk home although I was able to take advantage of a mile long downhill near my house.

Surprised about the HS on your wife's CT-1. I've had both Record and Chorus threadless and not problems whatsoever. Again, the King is incredibly expensive in the UK. I had one on my Chas Roberts fixie, cost was about $150 at the then exchange rates. Now, about $190 at the current rates.
 
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