Zipp wheel failure
 

This seemed like a strange one. I have an older Zipp 404 powertap rear wheel, dimpled rim and has an aluminum braking surface, about 9-10 years old. Today I had it in the truing stand and was detensioning a couple spokes to true the wheel. I get to one, loosen it 1/8 of a turn or so, and hear a creaking and cracking sound. The nipple starts to pull out of the rim and then the wheel buckles perendicular to the spoke hole. I don't have an idea of miles on the wheel, but seemed a strange mode of failure.

Anyone have an idea of a 20h rim w/similar erd? This one needs a fork stuck in it. ;) Preferable to fail in the stand than on the road.https://uploads.tapatalk-cdn.com/201...7396b54a86.jpg

Hrm. Interesting.
I always thought the al brake track wheels had a carbon faring on an al rim. Wouldn't have thought they were susceptible to spoke tension

I just read about someone having a similar situation. They contacted Zipp and honored a warranty replacement. Same situation. Taking the tension off the spokes in a stand.

CF has always been structural for Zipp.

No the carbon on this is structural, it is built almost like a flattened carbon tubular rim with the metal brake track glued around the circumference. I put a washer under the spoke nipple just for kicks and it is still true and round and was holding tension last night. We'll see when I get home if there is a bigger hole in the rim. Zipp says its too old for them to get involved. Oh well. 8 years (5-8k miles) seems like not very long to say its terminal, but I guess this is why most of my bikes/wheels/etc aren't carbon.

i remember seeing that quite a bit back in the day. Always seemed odd to me.

That's how HED made some of their aluminum brake track models, older Jets and Alps models. However, as others have already stated, ZIPP carbon fiber wheels with aluminum brake tracks the CF rim was an integral part of the wheel's structure.

Current Jets as well.

That's how Hed Jet and Bontrager Aura wheels are currently made. But I wouldn't say that the carbon "fairing" is completely non-structural. Anything that increases the bending stiffness of the rim will improve wheel stiffness and durability, and the bonded on fairing will help to increase the rim stiffness.

I contacted Zipp about a possible crash replacement, and they said I'm SOL... not quite in those terms of course. Just for fun I put a nipple washer on and it trued right up. I still won't ride it with the sides still buckled, but found it interesting that it has held so far.

Check to see if they hubs fall under the recall. If so, you'll get a whole new wheel. Zipp even went as far as to take my other wheel back so i'd have a matching set. The front hub was a part of the recall though

I know you already made a call to Zipp but dealing with warranty I would always try to go through your LBS. They have a better relationship and avenues to exhaust then the end user. Good luck.

It's a powertap hub, rear wheel only.

I got the wheel second hand, so wouldn't feel right making it the LBS problem as they have nothing in it other than they sell Zipp wheels. The guy I got it from offered to take it back, we settled on splitting the difference and I'll rebuild it some day or eventually just sell the hub. There are good people on CL sometimes.

Good man. Yea didn't know it was 2nd hand. Looks like it will all work out in the long run.