Maybe to you pro's this will seem trivial...
Here's the symptoms: Riding up my driveway at 5mph, smooth and quiet as always. Suddenly, a loud clack-clack-clack starts coming from the rear. What the hell? The loud clack was happening every 1/3 tire rotation. Rolling forward made the noise, rolling backwards was silent. Didn't matter if the bike was on or off. Wheel bearing? Disc brake loose? Everything seemed solid.
Into the garage, put the bike up so the rear tire is free. Still clacking, close inspection reveals the belt is the culprit. I can see the belt 'sticking' to the sprocket (only every 1/3 rotation) and then suddenly with a loud clack it will jump back out to normal. OK, maybe it's a tension thing. Adjusted the tension from loose to normal to tight, and it's still doing it. Careful rotation and I can pin down the exact belt tooth that's causing it to stick. Inspection under a bright light showed there is no damage to the belt tooth or the sprocket.
Then I run my finger carefully over the belt tooth, and it's crazy sticky. The other belt teeth are not. I get a qtip and water and carefully clean out the problem teeth (spaced 1/3 of a rear wheel rotation apart) and ta-da! Silent again.
Apparently I picked up a sticky blob-o-something in the belt, and it spread via the sprocket to other belt teeth, but not all of them. The belt teeth would stick to the sprocket as long as they could and then let go with a loud clack. I suppose if I had just ridden it 10 miles it would have worn off the stickyness, but it took me completely by surprise and it sure sounded like something was really wrong.
Author
Topic: Belt Drive Clack (Read 889 times)