Originally Posted by
BarryII
This is an exercise bike and the bolt won't be spinning in the hole. There will be a nut on it. I think I have my plan. First week or two, undersized bolt and I'll watch it carefully. After that I'll see. There will be a second and maybe a third attachment point that may be strong enough even if the bolt fails.
Just so you understand, think about how you'd try to remove a fence post in the ground. You grab it and pull it to one side, then to another, then to the side, working your way around in a circle as you enlarge the top of the hole into a cone and keep working this way until you've worked it loose.
This is EXACTLY what will happen to your pedal shaft in the crank. As the crank turns the force applied to the pedal shaft is essentially rotating in the crank. The outer threads will be the first to go, and the process will continue until you have an enlarges hole and loose pedal. You might be able to retighten the nut, but the threads in the crank will be mashed to death.