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I wore the rim out on some cosign wheels from wiggle after 5 years,3000+ miles mostly commuting.
Which was fine, they had been light strong and cheap ish.
I found a DT branded rim which is the same diameter and bought new spokes. The old alloy nipples had cracked on lots of the spokes.
In sub 500 miles I've broken 4 spokes. One in the middle, one at the hub, two at the rim.
It's a 28 spoke build. I've not changed weight much or changed routes at all. I've not got faster. I'm not carrying any more stuff on the paniers.
Is the spoke tension too high? I built it to what I thought was the same tension as the previous build. All I was going on was the rough note of the spokes and how squidgy they feel when pulled together.
Suggestions welcomed!
Hmm, I'd be inclined to blame the spokes, especially when one is breaking in the middle. I had a brand new ACI break in the middle recently, definitely not overtensioned as I have a tensiometer and also could feel it was fine too. What are yours?
My view is that it's difficult to overtension spokes without making the wheel impossible to true (it will start "pringling") or damaging the rim or nipples. It might be controversial, but I think that if you've got a round rim that is flat in the plane perdendicular to the axle, centred and there is no damage to nipples or nipple-beds, you *cannot* have too much tension.
Normally, spokes snapping is the result of too *little* tension - as the wheel loads up during rotation, the transient loads on spokes increase too much. A wheel with even, high (as possible) tensions will load all of the spokes pretty much evenly, and so will last for ages.
As @branes points out, though, spokes rarely snap in the middle unless there is something else going on.
It might be controversial, but I think that if you’ve got a round rim that is flat in the plane perdendicular to the axle, centred and there is no damage to nipples or nipple-beds, you *cannot* have too much tension.
On some ali rims you will see the spoke bed deforming around the nipple hole if you use too much tension. Stans (?used) to set quite low recommended tensions for this reason.
Assuming spike tension is ok, did you check the stagger of the new rim?
Assuming spike tension is ok, did you check the stagger of the new rim?
Whats the stagger of a rim? The dish? That seems fine.
I used DT revolution spokes. They have a decent reputation ( I thought)
Did you go for the same cross pattern (or rather a sane cross pattern)?
Is the new rim has not go offset spoke holes and you've got it the wrong way around?
How even is the tension? The wheel might be round, but if there's a big difference between the tightest spoke and the least tight (on one side) then it tends to accelerate spoke fatigue while hiding the localised under tensioning.
IME DT Revs aren’t the best spokes - they’re just too flexible and quite tricky to get even tension, particularly without a tension meter. I’d replace them with regular double-butted spokes for all the massive 50g weight penalty and see how you get on.
Is the new rim has not go offset spoke holes and you’ve got it the wrong way around?
Mmmm, yes it does have offset rim bed. I can't remember how I chose which way round to build it. Mmm.
Did you go for the same cross pattern (or rather a sane cross pattern)?
Yes. It's a radial on the non drive side, Same as it was before.
How even is the tension?
I think it's even. No tension meter, I checked by squeezing the spokes and taping them and listening to the sound.
massive 50g weight penalty
There were light wheels, I thought I might make it as light as possible while I was at it. If I have to take it to bits I might get some heavier spokes. It's more of a pain limping home with no back brake than 50g.
Yes. It’s a radial on the non drive side, Same as it was before.
That's going to exacerbate the uneaven tension on a dished rear wheel. Perhaps the lightweight spokes are not quite coping with the extra tight / extra slack lacing?
I think it's one of the Holy Wars of cycling, and I'm old enough to remember Jobst Brandt and Sheldon Brown arguing about it endlessly. The one wheel I built with more crossing on the non-drive-side than the drive-side (I think I could only find spokes to do cross one and cross three lacing at the time) was one of the most abused wheels I've built and stood up to it well. I don't believe that there's significant wind up possible in a modern MTB hub, either.