Spokes

[ian emmerson]

I am currently experiencing spokes snapping, 1 last week and 1 today. Both spokes that have failed have been on the drive side.
Just wondering what could be causing this and is their anything preventative I could do to reduce this ?
I know they are factory wheels, so maybe not the best 700s for strength etc but current budget prevents me from buying better etc.
Also how easy is it to replace a spoke and straighten the wheel myself ?

Any help is much appreciated

 

[accountantpete]

Hi Ian - what make of wheels are we talking about and where did the spokes break?

Replacement is normally straightforward - take the cassette off in order to remove the old spoke and introduce the new one.

Truing with two spokes gone ideally needs a truing stand (or LBS) but you can do a rough job using the brakes as a guide.

 

[the snail]

Probably the spokes snapped due to incorrect (uneven) tensioning. My wheels were like this - they were true, but the spoke tensions were all over the place, and way too low. If you can measure up and get the correct length spoke, then replacing it and retensioning the wheel isn't difficult, you just need to be methodical and patient. Once the wheel is true and correctly tensioned it will be very strong, even a cheap one - the strength comes from the quality of the build rather than the components. I followed Sheldon Brown's guide:

http://sheldonbrown.com/wheelbuild.html

You will probably get a better job doing it yourself than taking it to a shop - lots of people seem to get repeated failures after having spokes replaced by LBS

 

[mickle]

The spokes have failed because they've been ridden on too long at low tension. Low tension allows movement at the hub end and this movement and flexing of the elbow has fatigued them. Particularly on the drive side, and particularly the driving spokes since these are under the most load.

So it's extremely unlikely that only two spokes have been affected, I suspect that you'll be popping spokes until all (8 or 9 of your 32 or 36) of the old drive side driving spokes have been replaced with new.

I'd go ahead and replace them all now, it'll be easier in the long run.

 

[e-rider]

Probably the spokes snapped due to incorrect (uneven) tensioning. My wheels were like this - they were true, but the spoke tensions were all over the place, and way too low. If you can measure up and get the correct length spoke, then replacing it and retensioning the wheel isn't difficult, you just need to be methodical and patient. Once the wheel is true and correctly tensioned it will be very strong, even a cheap one - the strength comes from the quality of the build rather than the components. I followed Sheldon Brown's guide:

http://sheldonbrown....wheelbuild.html

You will probably get a better job doing it yourself than taking it to a shop - lots of people seem to get repeated failures after having spokes replaced by LBS

Well, there are a few mistakes in this comment.

If the wheel was true but the tension in the spokes was all over the place then the rim was bent! The spoke tensions might well have been too low in general but variations in spoke tension exist in order to get the rim true. If you put the spoke tension at 'exactly' the same in every spoke you would not have a true wheel!

Secondly, I would agree that if you use high quality components but the wheel build is poor you end up with a crap wheel, however, if you use cheap components (esp. spokes and rims) the wheel will never be that great even if it's built by Gerd Schraner!

 

[PpPete]

Perfectly possible to make a robust wheel out of mediocre components - even second-hand ones. First wheel I ever built was entirely out of recycled components....built 2X because that was the spokes I happened to have. Now been 3 years since I built it - in which time it's completed several 100k audaxes and an E2E.

But as tundragumski mentions - if the rim is bent before you start building it ain't never going to be right. On that same E2E I tried to rebuild a factory wheel having failed repeatedly to true it (well I got it true, but tensions were all over the place so it went out of true in a matter of hours). When I took it apart completely I found the rim had a slight natural bow to it....

 

[mickle]

The legendary and now retired wheel buidler Bill Avis tells how he took a wheel apart, straightened the rim against a tree and rebuilt it, at the side of a road. In the middle of a tour it was his only option. He probably acheived it in the time it took to make a cup of tea. But yeah. You can't build a wheel with a bent rim and hope it'll last.

 

[gwhite]

While the spoke tension on cheap factory-built wheels is always too low, what really gets me is that the dishing is all over the place. The number of new front wheels we receive which are dished is unbelievable and the rears all too often have the dish reversed. Now I know these are relatively cheap but if the machine operators were properly trained these could be built. to a reasonable standard. A monkey and peanuts problem I expect.