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.