bpcyclist

Greetings, cycling geniuses. I am currently riding a one year-old BMC SLR02. The only previous issue I have had was some buzzing form the front of the bike, which turned out to be a loose valve nut, if that's what you call it. It was quiet for several months, then louder buzzing/rattling appeared from the front end, or so it seemed. It basically sounds like a giant Jew's Harp being played. It is only heard when riding over rough pavement and is silent when on smooth pavement. It is heard both when pedaling and when coasting. It is intermittent. Interestingly to me, I never hear it in the first few minutes of a ride ever. It's only after I've been going for a bit that is appears. Once it gets going, it stays going until the ride is over or I am just on smooth pavement. I have also never heard it when in the lowest (easiest) gears. It seems the bike has to be moving at a certain pace for this sound to really show up. I have reproduced it a couple of times by picking up the front wheel and dropping it. But most of the time, when doing this maneuver, you will not be able to produce the sound. Oh, and applying the front brake and rocking the front wheel does not produce this sound either.

I have checked every bolt in the cockpit, the brakes, the wheel, and the hub. Everything is snug. I closely inspected the forks, steerer tube, front end of the down tube, and no cracks are visible. Have checked the cables where I can see them (bike has internal routing). Have made sure the valve nut is tight and that the valve does not appear to have any play in its positioning at the aperture. All spokes seem to have reasonable tension and the nipples seem to be in the right place and not loose. I have picked up the front wheel and shaken the heck out of it and I hear no loose debris moving around in the wheel. The QR is snug, though I undid it and re-did it and the sound persisted. And last, I can't recreate this sound by manipulating the shifters/brake levers.

So, given all that, I am wondering what next steps might seem reasonable. I am no bike mechanic. I can do the very basics, but I certainly have never taken apart a hub before. What suggestions might you have for me? It is really annoying to be trying to enjoy a nice ride on this terrific bike, but constantly be distracted by this buzzing. I don't like to wear earphones when riding. But this morning, the noise was so annoying I just had to put them in so I could escape it. Any help is greatly appreciated. Oh, and lastly, these wheels are Aksiums. I have never personally heard a Mavic Death Squeal, but from reading about it, this does not seem to be remotely similar sounding. Thanks in advance.