Pedal arm issue

[STURDYTOON]

The pedal arm keeps coming loose on my caad9 - I have tightened both bolts that keep the arm in place but the arm still works loose after a short time - the small gasket type fitting has broke is this likely to cause the problem ?

[coolboarder]

What do you mean by the pedal arm - presume you mean a crank. We need to know the make of chainset, how it fits to the bottom bracket axle and which side is coming loose?

[STURDYTOON]

Pls see pic - P1080405.jpgP1080402.jpg

[Mike the bike]

Looks very Shimano. And nothing wrong with that; mine is identical and hasn't misbehaved in the last three years.

I think I remember that the plastic security tab must be fitted and in good order or, as surely as night follows day, the bits will work loose. I think you can buy a replacement Sturdy, for a very small price.

[coolboarder]

Not sure how this type of crank fixes to the bottom axle spindle but if the tightening screws have been allowed to loosen and the crank has moved much on the spindle then wear could occur to such an extent that you may never be able to tighten it securely again. If there is supposed to be a washer/security tag thingy than can be replaced then hopefully that will solve it otherwise, sadly, you may be looking at a new crank.

[puddings]

Although I have used HT11 on road bikes without any issues since they launched, I did have a troublesome one on one of my MTB's a couple of months back and it was all down to the lock tab not locating correctly which was then allowing the retaining bolts to come loose. I happened to have a spare but you should be able to get one from your LBS.
Also check that you are doing the bolts up tightly enough - original versions were shipped with too lower torque setting. IIRC the recommendation is now 12Nm with a recommendation to retighten after 200km.