bizarre bike wheel failure

[Number_35]

Last week I donated blood, and as if to prove that no good deed goes unpunished, came out to find my rear tire flat. I had all the stuff for the repair, so removed the wheel, removed the tire and tube, found the puncture, patched it, put the tube and tire back on, and was pumping it up with my little hand pump when suddenly the wheel made a "sproing" sort of noise and sprung out of shape. What the ...?!!

I didn't have a spoke tool with me, and couldn't even walk the bike home (the rear wheel was too deformed to roll without hitting the frame), so phoned my wife to pick me up with the bike rack on the car.

While I waited, most of the donor care associates and nurses trooped out to view the carnage and offer me yet more post-donation food and drink. (Red velvet cake shown.)

Bought a new wheel from my LBS, got my bike going (transferred over the 8-speed cassette, rim tape, tube, and tire) and then loosened off all of the spokes on the warped wheel. It came back some, but I don't know if it's too far gone. (Experts, and I'm looking at you, NYEngineer, do you think this is salvageable, or should I give up on it?)

Jr figures my truing adjustments over the years created an imbalance that was kept in check by having an inflated tube and tire in place. I think that I need to buy a tension gauge (Park Tool makes one) to prevent this happening again. Does anyone have a recommendation for a reliable spoke tension tool?

I am very thankful this didn't happen on a bike trip!

 

[HangFire]

Too many adjustments for truing the wheel, that added up to what you have there. You can't just loosen one side and tighten the other forever. You have to consider wheel roundness, tension, etc.

I doubt it it can be saved, it would take more patience than I have to get it close to true again.

 

[CR94]

I've read of that type wheel failure, but can't recall the proper name for it. If I recall correctly, it can be mathematically proven ('tho not by me!) that the wheel structure becomes unstable if spokes are too tight in relation to rim stiffness. Essentially, it's a buckling failure, much like what happens with excessive compression loading of a thin column.

 

[supton]

I've heard of taco'ing a wheel but never when sitting. That much warpage and I'd just replace it.

Maybe you had the spokes too tight? I think I have only trued up my wheels every couple of years, and I only aim for "good enough" out of fear of doing worse damage.

 

[skyactiv]

It doesn't take an engineer to figure out that wheel isn't salvageable. However, I'm sure there are people in Africa that would fix it. Fire and a creek is part of the method I'm guessing

 

[JLawrence08648]

Loosen the tension on all the spokes then see how out of round the wheel is. Any spoke tool will work but I always use a $75 tensionmeter when building wheels and a wheel stand. The tension in the cassette side is higher than the other side.

 

[CR94]

Originally Posted by skyactiv
It doesn't take an engineer to figure out that wheel isn't salvageable. ...
Rebuildable if the rim isn't cracked, and isn't warped when spokes are removed.

 

[spasm3]

I'd never trust riding on that again, new wheel.

 

[Billbert]

Once you potato chip a wheel it's done.

 

[JLTD]

Originally Posted by Billbert
Once you potato chip a wheel it's done.

Potato chip 🤣

Perfect description! Glad it did not happen on the ride OP, and that you have it fixed…

It's art now.

 

[AZjeff]

Originally Posted by CR94
I've read of that type wheel failure, but can't recall the proper name for it.


Potato chip or taco'd as already noted. I've seen it happen when 1 spoke breaks.

Wheelsmith was the standard but it appears it's not made any longer? Park makes one now. It looks like there are cheaper ones on Ebay but why would you?

 

[CR94]

Originally Posted by AZjeff
Originally Posted by CR94
I've read of that type wheel failure, but can't recall the proper name for it.

Potato chip or taco'd as already noted.
That's colloquial biking jargon, not the proper engineering term.

 

[AZjeff]

Dynamic collapse then. Search bicycle wheel failure, a PDF with a scientific description is about 4 down.

 

[Kestas]

I once bent a wheel when I slipped and crashed on wet leaves. Being a poor high school student I bent it back, trued it, and put it back in service.

 

[Kira]

If it's gone, it's gone.
You can try this.
After loosening it, put a block of wood on the floor and put the bend facing (pointing?) down and stand on both sides of the bend and try bending it back.
This has worked for me.

 

[NYEngineer]

Yeah, Chuck... The Park Tensiometer is a good tool. It isn't necessarily calibrated out of the box but it will give you consistency from spoke to spoke. I keep meaning to build a fixture with a weight and a spoke to calibrate mine but it hasn't failed me yet. I think it was about 60 bucks. Money well spent.

That wheel would have been a prime candidate for my comical trailside repair... Remove the wheel from the frame, find the worst part, line it up against the ground and give it a solid whack. I've gotten handfuls of guys out of the woods with that trick.

Replace that rim with a Velocity Cliffhanger. Oh wait... You already bought a wheel? Bummer.

 

[AZjeff]

Originally Posted by NYEngineer
That wheel would have been a prime candidate for my comical trailside repair... Remove the wheel from the frame, find the worst part, line it up against the ground and give it a solid whack.


Or 6 if that's what it takes. Disc brakes have made this fix more likely to get you back to the truck.

 

[NYEngineer]

Originally Posted by AZjeff
Originally Posted by NYEngineer
That wheel would have been a prime candidate for my comical trailside repair... Remove the wheel from the frame, find the worst part, line it up against the ground and give it a solid whack.


Or 6 if that's what it takes. Disc brakes have made this fix more likely to get you back to the truck.



Exactly. And it's always good for a laugh.

 

[Number_35]

Originally Posted by NYEngineer
Yeah, Chuck... The Park Tensiometer is a good tool. It isn't necessarily calibrated out of the box but it will give you consistency from spoke to spoke. I keep meaning to build a fixture with a weight and a spoke to calibrate mine but it hasn't failed me yet. I think it was about 60 bucks. Money well spent.

That wheel would have been a prime candidate for my comical trailside repair... Remove the wheel from the frame, find the worst part, line it up against the ground and give it a solid whack. I've gotten handfuls of guys out of the woods with that trick.

Replace that rim with a Velocity Cliffhanger. Oh wait... You already bought a wheel? Bummer.
NYE, you had previously talked about whanging the wheel on the ground as an expedient field repair. I didn't know what you were trying to correct, but do get it now.

The replacement wheel says "EVO E-Tour 26"/ETRO 559 by Stars Circle". Not too much turns up the 'net. Hmmm. Oh well, it was what my beloved LBS had in stock, and the price was right (C$73.99 + 12% sales taxes). I'll check out the Velocity Cliffhangers.

Hats off to Supton and Billbert for perfectly describing my old wheel - "taco'ing" and "potato chipping" indeed!

AZJeff, thanks for pointing me in the direction of that paper:
https://www.eiseverywhere.com/retrieveupload.php?c3VibWlzc2lvbl8xMzA5OTVfNzQzODIyLnBkZiplc2VsZWN0

I think that this statement from the paper's abstract describes my situation:
"We find that increasing spoke tension increases failure load, unless the spoke tension is close to the buckling tension, in which case the wheel will collapse under even a small disturbance."

I think I had those spokes so tight that they exceeded the buckling tension of the rim. Anyway, I've got a Park TM-1 on order from MEC, and will establish a baseline with the new wheel, and then have a go at rebuilding the old one (and checking the other wheels in our fleet). We will see. Thanks all who contributed to this discussion!

 

[CR94]

Originally Posted by Number_35
... I think that this statement from the paper's abstract describes my situation:
"We find that increasing spoke tension increases failure load, unless the spoke tension is close to the buckling tension, in which case the wheel will collapse under even a small disturbance."

I think I had those spokes so tight that they exceeded the buckling tension of the rim. ...
Yes, exactly---as I stated back in the third post of this thread.