Yesterday as I was removing the cranks from my project bike (and some skin from the knuckle of the first finger of my right hand) I noticed that the right (drive-side) crank was much tighter than the left crank. As I washed and bandaged my knuckle, it occured to me that this is usually the case. Now understand, I'm talking about a standard three piece cotterless crankset which requires a crank puller to remove the cranks. I suspect that pedal forces tend to tighten the bolt on the right side crank, and loosen the left side bolt.

Am I on the right track or is this just a crank theory?