Author Topic: Re Bolt working lose on drive side crank Nomad Mkii  (Read 560 times)

Dave B

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Re Bolt working lose on drive side crank Nomad Mkii
« on: March 28, 2020, 03:07:58 PM »
Hi, the crankset bolt , drivel side,on my Nomad II was replaced by my lbs due as it showed signs of rounding off. The replacement keeps working itself free. Over tightening results in a creaking noise. I  tried lock tight but eventually the bolt still worked itself free. Is it just the case of purchasing another bolt, any ideas of part required? Thanks

mickeg

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Re: Re Bolt working lose on drive side crank Nomad Mkii
« Reply #1 on: March 28, 2020, 08:10:26 PM »
There are lots of different cranksets on Nomad Mk II bikes, I have no clue which you have.

If it is a square taper crank and if it is the bolt that holds the crank to the bottom bracket and there is an audible creak when it is too tight, that makes no sense to me. 

If that is what it is, it makes me wonder if the bike was ridden too long with a loose crank arm.

If it is one that uses external bottom bracket bearings, I can't help.

Dave B

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Re: Re Bolt working lose on drive side crank Nomad Mkii
« Reply #2 on: March 28, 2020, 09:38:50 PM »
Thanks for the response. Yes it's a square taper crank set.  The bike is eight years old, the bb was replaced last yrs.  The none drive arm also had to replaced recently. Its possible the drive side could have been run loose.

mickeg

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Re: Re Bolt working lose on drive side crank Nomad Mkii
« Reply #3 on: March 28, 2020, 10:22:56 PM »
About a decade and a half ago, I was riding a bike that I had recently built up.  And I noticed a slight squeaking noise down in the pedal and crank area.  I had a multi tool with me, immediately stopped and started checking everything down there.  The drive side crank arm bolt was pretty loose, I tightened that up as tight as I could get it with that small wrench.  And went home and used a torque wrench to tighten that bolt to specification.

This would not solve your noise problem, but I can say that when i tighten that bolt on my bikes with a torque wrench, the bolt stays tight enough that it stays in the bike and does not fall out.  But the bolt will be noticeably looser after several hundred miles.  I never worried about it being looser since the crank arm stayed in place and I installed it to manufacturer torque specification.

I suspect (this is only a guess) that the crank arm slowly tightens onto the square taper spindle over time because the bolt continues to apply pressure against it and that was enough to cause the bolt to become slightly looser with some distance on the bike. 

Since then I usually use a torque wrench on crank arm bolts.  The exception is that when I take my bike on an airplane I have to remove the crank to fit it into the case, for that I do not use a torque wrench as it is too big and heavy.

I have heard that if you ride a bike with a crank arm bolt too loose for too long, that can damage the crankarm.  Fortunately the one time I did that, I did not ride it enough to cause damage.

PH

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Re: Re Bolt working lose on drive side crank Nomad Mkii
« Reply #4 on: March 28, 2020, 10:28:38 PM »
The only time I've had a crank bolt loosening was down to a poor fit between crank and spindle, the crank squirms on the spindle taking pressure off the bolt.
The surest way to test that is with a swap, the same crank on a different BB, or a different crank on the same BB. 
« Last Edit: March 28, 2020, 10:30:38 PM by PH »

Dave B

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Re: Re Bolt working lose on drive side crank Nomad Mkii
« Reply #5 on: March 29, 2020, 08:26:28 PM »
Thanks, I suspect that may be the issue.