Originally Posted by
bikeyboy
Keep it tourqed down. Check and tighten before it gets loose.
+1. I've never needed any thread locking compound on a bicycle component. However, you do need to make sure the attaching bolt is torqued properly. Without running to the garage, I am guessing the crank bolt on a square taper or ISIS/Octalink crank is about 30 ft-lb (~40N-m). It is quite a bit of install torque, and I use automotive tools and torque wrench. That said, I've never had a crank bolt (or any properly torqued bolt) come loose.