Originally Posted by
joejack951
The problem would not be fixed by reverse threaded crank bolts.
I do not believe you are correct. If your statement were true, right cranks would fall off as often as left cranks. They don't. I've replaced hundreds of left crankarms in 25 years of wrenching. I can't remember ever replacing a right arm with the same problem. Pedalling action keeps the right tight but loosens the left.
Originally Posted by
joejack951
The problem is the weak aluminum deforms (or the bolt loosens due to undertorquing allowing the crank arm to come loose) which ruins the tapered press fit that previously existed.
And what allows the press fit on the left to go sour, while apparently keeping the right side snug? Loosening of the nut/bolt. What loosens the nut/bolt? Pedalling. Reverse the thread and watch the problem disappear.
Originally Posted by
joejack951
Once that happens, the matched taper on the crank arm and BB spindle is gone and you'll have to be very lucky to get a tight fit again.
Once that happens, luck ain't got a thing to with it. It's shot. Period. Time for new crank arm. Anything else is a waste of time and energy.