Pedal arm came loose

Aug 30, 2020 - 9:43 AM

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  • My creaky bike took a turn for the worse today when the pedal arm came loose out on a ride! Almost came off once it became loose, very quickly.

    Luckily a friend had a tire tool that kind of fitted the hex and I had to ‘tighten‘ it every quarter mile ...

    I think this is getting serious now AM, I’m very very annoyed. It’s now falling to pieces.

  • Hi @simonbugler A loose crank on a square taper bottom bracket is a common issue that arises because the crank is not fully tightened on. It happens because as you tighten the crank bolt you are forcing the crank arm up a taper. What feels 'tight' (in terms of effort put into tightening) may not be. A bit more effort and you can get another turn or two out of the allen key. Sounds like someone in the factory got it wrong. The fact that you were 'tightening every 1/2 hour' suggests you in turn never got it tight. It needs an 8mm allen key ( I don't like the sound of any tool that kind of fits! ) and if using just an allen key (probably a 100mm lever rather than a hex socket and wrench - more like a 200mm lever) you will need to give it quite a lot of force. Don't be fooled by the first resistance you meet - that is the crank beginning to bind on the taper. Best would be to get someone with a full socket set which included an 8mm hex socket and torque wrench. If you do find that aim for about 40-45Nm. It is not falling to pieces -- it does need tightening.

  • On the side of the road This morning it was very much falling to pieces.

    I didn’t have a 8mm Allen key with me. The tool that fits is the best tool that got me home.

    I’m kind of getting annoyed with your responses on this forum.

    Sticking up for what is turning out to be a sub standard product isn’t helpful or required. If this was a how to repair your 20 year old bike it would be. But just telling me that it’s an easy fix really isn’t.

    I paid a lot of money for this bike! I don’t expect to be repairing anything.

    I’m truly shocked at the lack of official response. A total disgrace.

  • And it appears it coming undone mid ride has caused further damage!

    I have managed to get it back on.



  • @simonbugler Yes well that has now destroyed the crank. Sorry you feel annoyed. Only trying to help. Wasn't a defence of the product simply a diagnosis of the problem and a possible solution.