Wheel build disaster!

[I like Skol]

Not sure what just happened but I am hoping undoing everything and starting again is an option.

I am rebuilding a rear wheel for a tandem using the old rim and hub. Apart from the fact that the hub is an internal brake so has larger flange diameter than normal it should be a typical build like I have done plenty of times before.

I was just getting near to the end, roundness was acceptable for a used rim. Side to side and dish was about right. Spoke tensions felt pretty regular. I reckon I was just a few minutes from calling it a day when the weirdest thing happened. I tweaked a spoke a little and let go of the wheel then it started pinging and twanging and within 10 seconds I had a pringle! I thought that a spoke or spokes must have ripped out of the rim but they are all ok. I also checked the flanges to make sure these haven't parted from the hub and they are ok too.

What the hell happened? Wheel is now out by approx. 10mm in each direction so no option but to pull it apart, check the rim and start again. Has anyone on Cyclechat seen anything like this before @Spoked Wheels @Yellow Saddle

 

[Venod]

Its got to be uneven tension on the spokes, I can't think of any other explanation if the rim is sound.

 

[Yellow Saddle]

Not sure what just happened but I am hoping undoing everything and starting again is an option.

I am rebuilding a rear wheel for a tandem using the old rim and hub. Apart from the fact that the hub is an internal brake so has larger flange diameter than normal it should be a typical build like I have done plenty of times before.

I was just getting near to the end, roundness was acceptable for a used rim. Side to side and dish was about right. Spoke tensions felt pretty regular. I reckon I was just a few minutes from calling it a day when the weirdest thing happened. I tweaked a spoke a little and let go of the wheel then it started pinging and twanging and within 10 seconds I had a pringle! I thought that a spoke or spokes must have ripped out of the rim but they are all ok. I also checked the flanges to make sure these haven't parted from the hub and they are ok too.

What the hell happened? Wheel is now out by approx. 10mm in each direction so no option but to pull it apart, check the rim and start again. Has anyone on Cyclechat seen anything like this before @Spoked Wheels @Yellow Saddle

Is the rim permanently deformed? Can you undo the tension and get the rim to go back to form?

 

[I like Skol]

Haven't tried anything yet but bizarrely the spoke tensions are now all over the show. Tensions are all wrong though, where the wheel is pulled to one side the spokes on that side are looser. The spoke tensions appear to be opposing the deformation but it has deformed anyway?

 

[Yellow Saddle]

Haven't tried anything yet but bizarrely the spoke tensions are now all over the show. Tensions are all wrong though, where the wheel is pulled to one side the spokes on that side are looser. The spoke tensions appear to be opposing the deformation but it has deformed anyway?

It sounds to me like the wheel collapsed into a saddle shape (prezel). This is the classic Le Chateleur state for an overtensioned wheel.

How about a picture?

Edit: By Prezel in mean the colloquial term for a collapsed wheel, not the actual pastry shape. I don't know where this came from but it is commonly used. It should be potato crisp shape, but that's doesn't roll off the tongue as nicely.

 

[I like Skol]

It sounds to me like the wheel collapsed into a saddle shape (prezel). This is the classic Le Chateleur state for an overtensioned wheel.

How about a picture?

I don't think a picture will show much unless I could get it on a flat surface with a hole in the middle for the hub to sit in.

Pretzel/pringle? Wheel is now resembling one or the other but I think Pringle is the better likeness....

Tension was certainly no higher than wheels I have built in the past and I may well have made a couple of half turn passes around the wheel to increase this a little if it hadn't gone wrong this way.

Maybe this is something to do with tension (high or otherwise) and the larger flange? To be honest I was wondering if a two cross lacing pattern might have been better because of the larger hub. I reckon this would improve spoke angle at the nipple to make the spokes more radial? I don't have any technical reason for this suggestion except it seems to make sense to me.

 

[Yellow Saddle]

I don't think a picture will show much unless I could get it on a flat surface with a hole in the middle for the hub to sit in.

Pretzel/pringle? Wheel is now resembling one or the other but I think Pringle is the better likeness....
View attachment 380096 View attachment 380097

Tension was certainly no higher than wheels I have built in the past and I may well have made a couple of half turn passes around the wheel to increase this a little if it hadn't gone wrong this way.

Maybe this is something to do with tension (high or otherwise) and the larger flange? To be honest I was wondering if a two cross lacing pattern might have been better because of the larger hub. I reckon this would improve spoke angle at the nipple to make the spokes more radial? I don't have any technical reason for this suggestion except it seems to make sense to me.

How many spokes? High-spoked wheels compress the rim considerably more and require much less thension. It has nothing to do with the hub size or spoke lacing pattern.

 

[I like Skol]

36 spokes, like nearly all my wheel builds.

 

[Yellow Saddle]

36 spokes, like nearly all my wheel builds.

Even so, but as you said, you didn't perceive higher tension than your normal builds. Perhaps you underestimated the tension or perhaps it is a very lightweight rim. Should you undo the spokes completely, weigh the rim, let's see how sturdy it is. Weight is the best indicator.For instance, anything under 500g is not good for tandem use.

 

[I like Skol]

It is a Mavic of some description with double eyelets. Sticker says Module 3D Argent.

 

[I like Skol]

Mavic rim from the 80s.
Not got time to mess with it now, will unlace it in the morning and try again if the rim is still flat....

 

[dan_bo]

Sure the threads on some of the nips haven't failed?

Just a thought.

 

[Hacienda71]

Sure the threads on some of the nips haven't failed?

Just a thought.

Twat it against a tree and then jump on it, that normally works...

 

[dan_bo]

Twat it against a tree and then jump on it, that normally works...

Was the wheel straighter afterwards or not?

 

[dan_bo]

Was the wheel straighter afterwards or not?