Mystery noise - Mavic wheel

Back in May I started to hear a strange noise from my road bike. It's sort of a low-pitch squeal, though my friend describes it as "mooing" (like a cow). It's one of those intermittent things that are hard to recreate in order to find the cause. In general it happens when I'm coasting and going somewhat fast, > 15 mph, usually after I've been riding for 15-20 miles. It is accompanied by vibration that I feel in the handlebars, so I thought it was coming up from the front wheel, like maybe the brake was rubbing on something. I had the frame and fork checked to make sure nothing was cracked or loose, had the front brake adjusted more than once.

The friend who says my bike moos has been cycling many thousands of miles per year for almost 70 years and has never heard it before. He suggested having the hub looked at. I mentioned this to another friend who asked what kind of wheels I have. They are Mavic Ksyriums. When friend #2 asked this, I realized I had never tried an internet search looking specifically for Mavic noises. So I did one and found several videos made by people who also have mooing bikes. Such as this one. Another video, from a mechanic, said the cause was a worn freehub body.

So I brought the bike to the LBS and had them replace the freehub on the rear wheel. Picked the bike up yesterday, rode it today, and while coasting down a big hill about 30 miles into the ride, it mooed.

I guess the next step is to bring the bike back to the LBS, and this time show them the videos and other things online that I found. I might wait a few weeks, though, since I have some bike rides planned.

The story continues.

The first ride with the new freehub was fine until I was more than 30 miles into it. This was typical of the mooing -- I would generally have at least 15-20 miles of quiet riding and then the problem would start to happen. But the second ride with the new freehub, yesterday, was much worse. The mooing started on the first decent downhill, early in the ride, and happened often throughout the entire 58 mile ride. And whereas before I would feel a vibration in my hands, yesterday the whole bike was shaking. Not good.

Between these two rides I looked again at some of the online videos and discussions of this problem, which people have had with Mavic wheels for more than 10 years. There was no consensus on how to make the noise go away for good.

Today I took the bike back to the LBS. The mechanic who worked on it last week was there. I played one of the videos for him (which I should have done the last time I brought it in). He put the bike on an indoor trainer, turned the pedal by hand to get the wheel going fast, and was able to recreate the moo. Several other people who work at the shop heard it and came over, and they discussed likely causes for the noise. Then the mechanic took the new freehub out and examined everything. He found that the pawls showed signs of wear, as did other parts in the hub that can't be replaced. He recommended that I get a new wheel.

So the Mavic will moo no more, because it is being replaced. I am only replacing the rear wheel, because the front is still okay. I got this wheel set in August or September of 2014, and my rough estimate is that I've ridden about 7000 miles on them.

The bike shop is refunding the cost of the new freehub to me, since it didn't solve the problem, and applying it to the cost of the new rear wheel. Which will be a Shimano. No more Mavic for me -- I was perfectly happy with them until the mooing started, but would prefer a wheel that lasts longer.