My FS is heading to the shop for new bushes and bearings. So I figured I’d dust off my SS, and enjoy the dry conditions. Needed to shorten the chain, and figured I would swap out the BB at the same time.
However, I could not unscrew the crank ring fixing bolt (aka: That little plastic bolt thingy on the NDS.) Eventually gave up, and took a hacksaw blade to it. Worked a charm, and replaced BB, and shortened chain.
Come to replacing crank arm, and no plastic thingy. Now you may ask how important that plastic thingy is? I did too. Decided not very. With the help of gentle persuasion (aka rubber mallet) got the crankset sitting pretty tight against BB. Tightened up the crank bolts to required torque (Working out torque tension: Remember amount of effort to unscrew said bolt = About the amount of effort to re-tighten. Degree of accuracy = 0.5%)
Sneered at broken plastic thingy on way out to ride!
Result? Half way up hill, a good 10 miles from home. Entire crank arm slips off, still attached to my cleat. Hamfisted approach to fixing, stripped inner crank bolt. Rode home by having to kick crank-arm back on every 10 revolutions.
Moral of the story: I’m an idiot, and that little plastic thingy is quite important to preload the crank before tightening.