I had it several times, each time it went away after adjusting the belt. So there may be several things that can cause it, but belt adjustment is definitely one. On a side note they replaced my original belt under warranty due to abnormal wear and the new one has never chirped no matter how loose or tight it's been. Makes me wonder if the original run had belts that needed to be redesigned in some way and triumph kept it hush hush. My original one would chirp any time it was the slightest bit loose.