I don't recall the mileage on mine but I would reach up under there every time I put it to bed after a ride and check it. I felt the roller wiggle a little indicating the bearings were starting to get slack. And the belt was beginning to get very light scuff marks on the top of it that I could feel with my fingers. At that point, I zip tied the idler up and away off the belt and haven't touched it since. That was less than a year's use. I don't have that much vibration and I don't think they are worth the aggravation they can cause when they go south. Adjust your belt so it doesn't vibrate at your cruise speed. A destroyed belt and idler can run $500+ depending on where you are when they come apart.