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I am pretty sure this rim is shot, but wanted confirmation and/or a better understanding of what's up. I'm fixing up a donor bike that was pretty apparently stored outside for years. Despite that, many of the parts are salvageable -- so good in fact that I decided to just overhaul the bike rather than part it.

Except the wheels? Rear wheel was pretty badly out of true. So I put it in my stand, tested the spoke tension, it was all over the place on the drive side, from 80-140 kgf. Non-drive similar, but not such high tensions. I began backing off the spokes and trying to get drive side to about 105 kgf, non-drive about 65, and the thing got worse.

I backed off all the spokes until they were slack. The rim (a 23mm wide, 32-spoke aluminum with plenty of brake track, BTW) looked fairly straight. I had expected it to show evidence of being badly bent, but it looked no worse than plenty of wheels I've gotten nice and straight.

So, I began tightening again, moving up slowly. Probably 5-10 kgf per side. (It was tedious.) As soon as I got the drive side up to about 55 kgf (non drive would be about 17 at this point I guess) The thing started to pringle badly again. That's with tensions nearly perfectly even on each side. The rim's easily 1cm out of true.

I'm convinced this thing is a goner (not surprised given its history) but I've never seen a rim behave like this. Maybe all that weathering and corrosion has just made it completely and randomly unstable? I was thinking maybe the eyelets were failing in some spots, but of course, if I had eyelets failing or weak spots near holes, I'd see the move reflected on the tension. I don't. I get even tension and a really warped rim.

Anyone seen this on an old rim?

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    Consider ignoring tension and actually truing the wheel. – Daniel R Hicks Apr 22 '18 at 1:29
  • I'm not talking about solving for tension at the cost of trueness. This thing is so seriously out of whack during simple tensioning that it'll be impossible to true once reasonable tension is achieved. It was already at 140kg on some spokes as found (likely last bike shop dude's bad attempt to true it) and was still way out. I forgot to mention one of the spoke nipples was broken off. – WPNoviceCoder Apr 22 '18 at 11:28
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    I think Daniel means trying to get it rideable by solving for trueness at the cost of whatever your tensiometer says? – stijn Apr 22 '18 at 12:35
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    Ba da bing!!!!! – Daniel R Hicks Apr 22 '18 at 14:56
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Yes.

Once the rim has taken a set (ie it is really bent), you can only true it so far with tensioning spokes. Too much tension will strip nipples, or can even snap spokes outright.

You did right by backing off all spokes till they're all loose. Then use brute force to "straighten" it once you've identified the areas of the rim that are out. A large flat surface helps, or another rim that is known to be true. Flip things over and over, use elimination to identify the bad spot/s. The straighten the curves. This is sometimes done using a street drainage grate as a lever or plain old stomping, like this:

https://www.sheldonbrown.com/images/taco_smallIMG_5694.JPG

As long as you can pressure the high and low spots and make it "flat" then it could be trued from scratch.

If its really dead, then its dead.


However you say the rim looks fairly flat with the spoke tension all slacked off. That's puzzling, and I'd recommend a close look at the rim nipple holes. Could be some of them are a bit softer metal than you might want, and they're moving under pressure. Also check the hub end of the spoke to see if there's any damage to the flange.

Unless there's something really good about the wheel, it can suck up a lot of time and still come out with a sub-par wheel.

I have about 4 spare wheels for various bikes - as you come across good ones, then keep them.


I have a seriously dodgy wheel where one spoke has no tension at all. It goes out of true if I so much as finger tighten that one spoke. Its perfectly ride-worthy for me, but I'd not put it on someone else's bike without fully sharing the problem. As a rim brake wheel, true is more important than spoke tension.

Separately, I've wasted 4 hours trying to true up a front wheel for a give away. In the end I swapped the hub and spokes to another rim, and got the assembly and truing all done perfectly in 30 minutes.

  • With rims available for $20-$30, I believe I'm just going to rebuild on one. Deore hub on it cleaned up OK, so that can be reused. I'm just confused by how flat it is with no tension, and how bad it is with low but even tension. (And worse and worse the higher the tensions get.) – WPNoviceCoder Apr 22 '18 at 11:31
  • What do you use to judge initial tightness? Do you count threads protruding from the nipples? Or how far the tops of spokes are in the nipple? (Maybe the spokes were ground flush with the heads of nipples, before?) – aspseka Apr 22 '18 at 17:19
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    I'd suggest firmly placing the tensiometer aside until you arrived at a true and quite tensioned wheel. Only then check whether you need to tighten all spokes a bit more. – aspseka Apr 22 '18 at 17:21
  • @WPNoviceCoder maybe the rim's metal is weak in some areas and has already been bashed flat. So when you apply tension, the rim gets less-flat. I'd bin it as per your plan. (recycle-bin that is) – Criggie Apr 23 '18 at 1:18
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I've had exactly this problem - pringled a wheel by just setting spokes to expected tensions. Daniel R Hicks & aspseka gave the correct approach. Don't bother using the tension meter until you've got it true, then check if you need to tighten it an 1/8 or 1/4 turn all the way around and re-true.

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  • Hi and welcome to SE. Instead of adding a "me too" answer, its better to upvote the answers that worked for you. Your point about leaving the tension meter till later is fair but doesn't really address the question which is of a wheel badly out of true. – Criggie Aug 16 at 13:51

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