I just recently had two wheel repairs go through my shop that may or may not have anything to do with this. One was a rim swap on a Shimano 965 XTR front wheel that had tacoed from what was apparently a small hit. With only 24 15 gauge spokes, I was not overly confident that this wheel was the right choice for the customer. He is an expert who is competing in the NORBA series. The wheel went from my stand into his car and right to North Carolina this past weekend for the race at Sugar Mountain. On a very brutal course, he finished 4th. When I saw the wheel yesterday for re-tweaking, only two spokes needed retensioning and wheel had remained true.
Second wheel - A Mavic rim that had failed from the inside out. I have never seen this before. The rider is a big guy ( 200 plus) and rode the wheel awhile but noticed it was not round anymore. When I removed the rim tape, the inside wall had cracked and seperated in 2 places, yet the outside was intact. To be fair to the wheel, it had been in service for at least 2 or 3 seasons.
My point is this. Rims fail for a lot of reasons. Poor materials, poor builds, but most of all the enviroment ridden are all possible reasons. While it would be great to know why this rim failed, I am guessing the real answer will remain hidden among all the possibilities. From the description of the build by Rev Chuck and the experience I know he has, I do not suspect the build. From my experience with thousands of wheels, I do suspect the rim. And that is not a slam on Mavic. They make fine products. But they make thousands and thousands of them. 100% reliability is not reality. Defects happen. Fix it and move on.
I will say this. As a wheel builder myself, this thread has me looking closer at the wheels I am building now and in the future. It is so very easy to become complacent and cocky doing something you have been doing for so many years. The man who taught me how to drive tractor trailers back in the early 70's gave me a piece of advice I carry to this day. "As soon as you think you know everything about truck driving (wheel building), that is the day you should walk away and never drive (build wheels) again. Thanks for the lesson.