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A couple of weeks ago, I broke 2 spokes and my rear wheel (27 inch) was seriously bent. I replaced these spokes and re-trued the wheel, but the next day the same thing happened, another 2 spokes snapped and my wheel was bent again. So I replaced the spokes again and re-trued the wheel.

Sure enough, the next day I broke 3 more spokes. I have repeated this "cycle" 5 times now within the last 2 weeks and I have no idea what I am doing wrong.

At first I thought the spokes were too lose so I made them all tighter, while ensuring that there was even tension around the wheel and a little extra tension on the freewheel side. When this failed I thought that maybe I had them too tight, so I tried again with the spokes a little looser but this failed too.

This wheel was purchased only 2 months ago and I have probably ridden it probably 1500 km. I also weigh about 85kg (190lb) and I very rarely ride on anything not paved. I am not convinced that the wheel has met its expected end of life based on this.

I cant determine why my wheel keeps breaking over and over again. Either there is something I am doing critically wrong in the truing process, the wheel is irreparable, or the bike shop just sold me a bad wheel. At what point should I just give up and buy a new wheel?

Edit:

I have been spray painting the spokes as i put new ones in and i found that the non painted spokes were breaking. Also they were breaking at the hub flange.

I have fixed the wheel to the point where I can ride it without the spokes breaking, but i still need to true it a little more. Im still not sure what I was doing wrong though.

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    What kind of wheel is it, and how are you checking the tension? – Batman Aug 7 '15 at 13:57
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    You may consider marking your replacement spokes (standard operating procedure for some mechanics) and sees if the original spokes are breaking or original and replacements. – Deleted User Aug 7 '15 at 14:09
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    Where are the spokes breaking? At the elbow (where they attach to the hub), or the nipple (where they attach to the rim)? – Useless Aug 7 '15 at 15:35
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    Assuming it's not a ridiculously expensive wheel I'd be tempted to take all the spokes out, check the shape of the rim and rebuild with new spokes. On a more expensive or particularly tricky wheel I'd get the LBS to do the same. 2 reasons: stress on other spokes when some break; some spokes are rubbish. – Chris H Aug 7 '15 at 16:31
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    Breaking spokes are usually a sign of low spoke tension. You can check easily by hitting the spokes lightly with a screwdriver. If the the sound is bass guitar the tension is too low! Have your wheel re-tensioned and trued! – Carel Aug 7 '15 at 17:44
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The biggest cause of broken spokes, that I know of, is inadequate tension. When the spokes are tight enough they flex a little bit with every turn of the wheel as the spokes at the bottom of the wheel unload slightly and then tighten again as they move around to the top. Over time this bending back and forth weakens the spokes – usually at the bend where they pass through the hub – and eventually they break. The cure is to build the wheel with sufficient tension to prevent the flexing.

If the wheel is old (and since it is a 27" wheel, I'm inclined to think it is) then the damage may already be done – although it sounds like you've replaced close to half of the spokes by now.

All of the above assumes that you're riding a more-or-less normal bike in more-or-less a normal way…

To be much more help to you it would be helpful to have answers to the comments on the original question above. As a very quick and dirty check of tension you could grab a "handful of spokes" (a set of 4 from both sides of the wheel) where they cross and try squeezing them. It should be quite hard to get any flex out of them.

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And these days 27 inch wheels are so old that the problem they have is overtightened spokes. People that do not know how to build wheels properly simply tighten them to pull a wow out of them. This works it's way around the wheel and they keep tightening them until they are at the very limit of their tensile strength.

The way to tell is that when spokes are too loose they will USUALLY fail at the bend. When they are too tight they will fail either at the spoke crossing or the nipple.

Spokes should not be so tight that they ring like a guitar string. Though there is a dull bell-like quality to properly tightened spokes.

  • When the tension is too high it’s usually the rim which fails. It also gets quite hard to turn the nipples which makes over-tensioning unlikely. – Michael Aug 12 '15 at 13:24
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Spokes breaking at the hub can be an indication that when the wheel was built the builder did not stress relieve the wheel.

See Sheldon Brown's article on stress relieving.

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