Bicycle Mechanics - Loose cramk arm!

Anyone know of a good way to stop my left crank arm from coming loose? I have been having to tighten it before every ride for the last 2 weeks. I tighten it down but am afraid I will strip or break the bolt. If I don't tighten it then it makes this annoying popping noise on every spin. Thanks.

Assuming they are square taper.....make sure the spindle isnt greased. They are held on by friction. Inspect the arm for damage, and then tighten the bolt like crazy. The bolts are supposed to be very tight.....you wont strip it.

Well see if the crank arm is rounding off of the b.b spindle first, then try using blue Loc-Tite on the threads of the fixing bolt.

lock tight. not sure which one thoug, #222 comes to mind for some reason, think i read that in the break it fix it ride it, i don't know what i'm talking about though. i just thought i'd post anyway

Thanks to all. Ritalin, not sure what you were talking about, but thanks anyway.

Careful on the torqueing, that bolt may not strip but it will break leaving you with the chore of removing the stump. It is possible too to extrude the crank down the square taper and enlarge the taper in the crank. Look to see that there is gap between the end of the taper and the end of the square hole in the crank, if there isn't no amount of torque will tighten up the crank.

Ritalin was suggesting you use Locktite on the bolt to keep it from loosening. This stuff is available in any autoparts store and comes in three grades: low
grip, medium grip and strong or assembly grade. You have to degrease the bolt and threads in the spindle before using. Use the low strength stuff. The bolt will stay where it is put. Steve

Thanks!!!

If you rode with the crank arm loose, it is quite possible that you wore the 'hole' that the spindle passes through.

This happened to me. If so, you will have to buy a new crank arm -OR-, if you are a tightwad like me, then you can put a sheet of aluminum foil around the spindle between the crank arm hole and the spindle. Then tighten the bolt. This has worked so far on one of my mountain bikes for over a year now.

i had the same problem..... but instead of buying a new part my dad being the bodge it and leg it he is filled it full off a thing called araldite... its like industrial glue and last for ages... Take the crank arm off.... remove any dirt and plaster the whjole thing full of a araldite and pop it back on..... make sure the glue doesnt run by putting a layer of masking tape over the top... leave it for 3-4 days... pull the tape off and test it.

Make sure you put araldite onto the end of the crank... this will help seal the crank and provide more strength... this should do the job...