But it's not just about felt vibrations, and even if you cured that annoying issue without a tension devices with the long length of the Spyder belt, I guarantee it's still vibrating or flapping around which can drastically shorten the life of a belt and cause them to break. This is why just about every belt drive system has some sort of tensioner in place from cars, to other motorcycles that use belts, to even my John Deere mower deck. You always want to keep your belt tight under any load or deflection. Now the fact that BRP/Canam didn't engineer a better solution out of the gate sucks, because they could have done something like Ducati with a pulley under the drive sprocket or something like that. The roller arm keeping pressure on the belt maybe isn't the best solution, and does add another wear item in play, but it's probably better then nothing in the long run.