Originally Posted by Redpath
I was wondering how others handled these things. Is there a preferred technique for bumping rim dents?
The one thing I always look for relative to "can it be saved" is radial true / roundness or flat spotting. If the spokes sitting directly adjacent to the the point of impact are loose or significantly alter the lateral trueness / side-to-side run-out of the wheel with even minor adjustments it's a pretty good bet that the rim has been permanently deformed. While it's possible to get the wheel laterally true, if the rim isn't replaced chances are you'll eventually find that your wheel will not stay in true and/or will be plagued with spoke breakage and unusual tire wear from the out-of-round condition.
As for fixing bent sidewalls where the rim was flat spotted, been there and done that. If you have either the correct tools or are really careful you can sometimes save a rim. However, the other thing to look at carefully when evaluating if a damaged clincher rim can be salvaged both before and after any repair efforts is the integrity of the rim's hook bead: the upside-down "L's" on the right hand illustration below.
If the impact damage or a repair method deforms either one of the rim's two hook beads I would replace the rim. Given that it's those small lips that keep your tire on the rim, you really don't want them to have any flat spots or other defects. Of the 3 rims I've replaced in the past 5 years, two were discarded for questionable hook beads whereas only one was discarded for a slight flat spot that was taking a toll on tire life. If I think of it, I'll take some photos as I'm pretty sure I still have the rims hanging from a hook somewhere in the garage.