....I have overhauled enough bikes with Stronglight and TA cranks with the caps
so firmly corroded into the arms that I have mixed emotions about the originals.

I often as not, on a standard 22mm socket, replace the metal ones with some
plain generic plastic ones that end up in the parts bins at the bike co-op.


For the TA and Stronglights where the caps are either missing or unsalvageable
with appropriate drilling, Freeze off, and cursing, I often use a pair of these things
as replacement crank arm bolts.



On a personal level, I like to have something in there to protect the puller threads.