So this happened(would like some advice)

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10/10/2016 12:22 PM

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I was just riding around normally and all of a sudden my crank arm fell off!
I didn't have any tools so I had to walk home like an idiot.
When putting my bike together I put the bolt on almost as tight as I could and this still managed to happen.
How was the bolt even able to loosen?
Is there any way to fix this without any tools if this happens again?(I'll always bring tools now, but just in case I forget)
The sprocket is a Kink Minus One so it looks like there is a tooth missing but really there isn't.
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10/10/2016 12:41 PM

I had a 3 piece years ago that used to work loose. Problem is, it's probably been ridden loose which actually microscopically stretched the thread the bolt won't bite like it once did. I solved my problem by using a healthy amount of thread lock on the bolt.

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10/10/2016 2:13 PM

New drivetrain parts won't hurt.

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Scooter kid trying to ride a bike.
@scootereyn

10/10/2016 2:22 PM

Stevearcade wrote:

I had a 3 piece years ago that used to work loose. Problem is, it's probably been ridden loose which actually microscopically ...more

I've only been riding it for about a month, I don't know if it should loosen that quickly. I'll tighten the bolt as much as possible and if it comes off again I'll resort to loctite.

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10/10/2016 2:48 PM
Edited Date/Time: 10/10/2016 2:48 PM

Did you re-torque/ check all of the bolts before riding (especially if newly installed)? Takes minutes and can save you some big trouble.

If it's simply coming loose after, or during a single sesh, thread locker would be the next step.

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10/10/2016 7:17 PM

When i took my cranks off once and tried to put them back on i would tighten it a lot but then the crank arm would be able to come off very easy. I realised i was missing this spacer. Check if you have the spacer.

https://www.google.com.au/search?q=crank+bolt+and+spacer+bmx&espv=2&biw=1366&bih=662&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi71Mrq1tHPAhVG7GMKHdeuDXYQ_AUIBigB#imgrc=uKE65Mx2_1uwaM%3A

If thats not it use some thread locker or plumbers tape.

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10/11/2016 12:01 AM

I'm betting you just didn't tighten it enough. That bolt will easily take a good 40Nm of torque. I'd be concerned the splines are worn now. Put a bit of grease on everything and tighten it up. Ride around a bit, do a few hops, then check if the arm rocks, or if the bolt has loosened

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10/11/2016 5:56 AM

what grump said also check the threading to make sure its not stripped, could be that you might have over tightened the bolt and damaged it

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