I have a wheel which has serious damage in two places. First - there is a huge wobbly-wheel due to side collision (5mm) and second - there is a dent on a braking surface. I'm curious - is there any change to true this wheel? Rim is very strong, I'm not sure if I can bend it with my hands or body weight.
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2Low-spoke-count wheels are a lot harder to true. Among other things they depend a lot more on the stiffness of the wheel, and if the wheel is bent at all you need to deal with that separately, without using the spokes to force it true. And a dent on the brake surface would require some metal-working skills to rectify (if it can be rectified).– Daniel R HicksJun 4, 2016 at 17:47
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the dent is not so huge and repairable I think. I disassembled the wheel (god it was hard) and all I need to do is to bend the rim. How I can bend it?– alexey polusovJun 4, 2016 at 18:35
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Well, you need some tools. At an absolute minimum some sort of adjustable wrench or "Vice Grips" style pliers (though the latter will badly scratch the surfaces).– Daniel R HicksJun 4, 2016 at 20:11
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I think I'll use a press I saw in a car workshop. But how do I know where to bend and how much?– alexey polusovJun 4, 2016 at 21:01
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1Ah, that's where the art is!!– Daniel R HicksJun 4, 2016 at 21:02
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1 Answer
I guess you have an aluminium/aluminum rim, which doesn't take kindly to rebending. Steel is generally okay to bend, but I have no experience with CF wheel rims.
Tool for rim tweaks is Vice Grips - with layers of padding in the jaws. If you can find the ones with ~50mm wide clamping surface, that distributes the pressure better and reduces the localised "bottle lid" effect.
As for bending the whole rim back to approximately flat, lay a broomstick on a flat concrete floor, then stand on the high bits.
Kind-of like this but not using the axle, since its a bare rim you will want to overbend it so it ends up straight. Use the flat concrete floor and look for wobble.
If the wheel is this bad, its dead. Straightening this wheel is a get-home fix only Notice in the middle where the join has wrenched, and now the braking surfaces will have a lip? Also the whole join is stressed and may give way anytime.
Regardless, once you have your rim straight, examine it closely, both sides, for cracking. Spend at least 10 minutes on this and even use a loupe or magnifying glass on anything suspicious. Check in the braking surfaces, the spoke side, and in the tyre valley.
Alloy does not bend back very well, so you might be best off replacing the rim rather than rebuilding it.
Aside - don't misplace any spokes or nipples! On my 20 spoke shimano front wheel, the oversized nipples go at the hub and are $14 each to buy, and the spokes have to be hand made.
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1have you even read my question? Rim is 35mm height and my 70kg sitting and even jumping on the edge of the rim did absolutely nothing. Rim is hard as a rock. I'm looking for a hydraulic or air press to bend it, but I don't know how. Jun 4, 2016 at 22:31
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1@alexeypolusov I did read your question. You will need to jump on the rim to exert enough force to straighten it. Or get a second/third/etc person to help by jumping on the other side from you. A rim that could be bent by mere hand pressure could not stand pressures of riding. Your other option is to simply buy a used replacement wheel from ebay etc. Front wheels tend to outlast rear wheels. Lastly - how did the damage happen? If you're the victim of an accident, you should be able to get the party-at-fault to repair/restore your bike?– Criggie ♦Jun 5, 2016 at 4:05
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1You know what? I came to a bike master - the old one. He is like 70 years old and is called by his patronim. Withoud any hesitation, he took the rim, put it on the L shaped steel door frame and started to kick the damn thing. I thought - omg, now I can only throw the rim in the dump. What the hell is he doing? After a few kicking-and-checking the rim was 99% true. Now I'm looking for a extremely flat surface to check the rim. Jun 6, 2016 at 6:13