Originally Posted by
auchencrow
I am familiar with Helicoils (though I've never actually done one) - However- if it is not as secure as a new crank, I would think I may be better off scouring eBay for a new one.
The threads formed by the Helicoil will actually be
stronger than the original aluminum threads. you will be removing a small amount of material thickness from the aluminum arm around the hole so it is theoretically slightly weaker in that area. I doubt you'll have an issue with it though as this is a common repair. If you wanted to do it yourself, the tools and supplies to do so would end up costing you more than a new crank arm however you'll have enough inserts to repair several crank arms. If this does not interest you, take the arm to your LBS and let them do the inserting. You'll want to use at least a drill press and vice for this process (crank arm removed from bike). Drilling by hand, especially with the arm on the bike, is not likely to yield a pretty result.