Warning: A story about a guy with time and mad skills saves a few $100.
I just extended the life of my SRAM Rival crank with the use of JB Weld. I recently purchased a new set of pedals (Look click-it) and shoes (Shimano). With all new pedals, shoes and cleats, I began noticing a hitch in the left crank whenever pedaling hard uphill. Some sort of give. Re-tightening the crank arm did nothing. I also began noticing the tell-tale sound of bearings (ceramic, mid-range price) on their way out.
So in anticipation of a big day Saturday (riding up to the finish of ToC stage 7 in advance of the pros), I decided to replace the worn bearings with the never been used stock bearings that came with the BB. Before re-tightening things up, I tested the fit of the new bearings. I was surprised there was so much give between the left side inner bearing race and the crank axle. It was not a tight fit at all, and partly explained the hitch I felt while pedaling. A high stress point, once wear begins along that metal surface (the crank axle support race), it just worsens with repeated use.
Ordinarily, this would mean a new crank is in order. But wait, perhaps I could extend it's life by tightening up that surface area by applying a layer of JB Weld? You know the stuff - 2 part epoxy that can do/repair anything/everything. I've worked with it extensively over the years, so I knew it was possible. The trick in this instance was ensuring that A.) it cured in time and B.) I didn't permanently weld the bearing to the crank axle.
The proceedure was: apply a thin layer along the axle mating surface, let it begin to cure with the aid of a heat gun, then slide the bearing over the axle to it's resting spot, quickly remove the bearing and clean off the squeezed out excess epoxy. After some additional heat assisted curing, slide a water moistened bearing (the inner race surface) over the axle one more time, and remove.
Before it fully hardens is the time to reassemble the BB and crank, this time using a thin layer of grease as the lubricant between the axle and bearing surface. The result? A rock solid fit. I'll know more once the climbing begins, but experience tells me it'll work fine.