Bent Rim Question

My rim is bent at the worst spot about 9 milimeters, the bent lasts for probably 12 drill holes on a 19" Try-all rim. The bend gradually increases to 9 mm in the middle. Repairable?

It is possible to straighten rims, but not a quick repair if you do it right. You need to unlace the wheel to do it right, and that means lacing it back together when your done. For most people this translates to: just get a new rim it’s not worth the effort. If you are still game for fixing what you have then read on. You might be able to make good headway by untensioning the wheel and straighening the rim as well as you can by eye. If you have a really bent rim you can’t get it straight by just truing it with the nipples. You will end up with seriously uneven tension, and before long a taco’d wheel.

First you need to have the right tools. For box section aluminum rims you can do a lot with a rubber mallet and blocks to support the rim; however, you need a flat surface to check how straight the rim is. When i used to straighten rims we had a piece of half inch thick steel that we used to check the rims. The steel was at least three feet square, probably much bigger (it’s been over 15 years since I’ve straightened a rim).

Put the suspect section on the blocks witht he high spot towards you. Hammer it with the mallet. Try soft blows at first to get a feel for it, but I remember a lot of spring back from the rim, and you will probably have to hit it pretty hard. You will want to pad the blocks with carpet, or something so that they don’t dent your rim. I used soft 2x4’s, they were soft enough that I don’t remember any damage from the blocks. After you hit the rim check the straightness, and continue where you see wobble.

If you have flat spots you need a special tool that is made to pull flat spots out of rims. That tool is very expensive, and so if you need it you will do well to find a bike shop with one and either pay them to pull out your flat spot, or if they are generous they may let you try your hand at it. I can’t think of a way to remove a flat spot without damaging the rim unless you have the flat spot puller.

I’d be interested to find out how it went if you decided to do it.

The rims already unlaced, sounds like a solid plan. I’ll definatly keep you informed. Thanks for the help, I appreciate it.