Expensive mistake. Great in theory for accommodating over-sized tandems that a Gates timing belt won't fit, but this belt falls off its rings (4 bolt 104BCD) frequently. I only have about 150 miles on my new tandem, and at a tandem rally this weekend, it fell off 6 times on one 45 mile ride. I have tried high belt tension, medium belt tension and low belt tension, as well as shifting the eccentric laterally by slight amounts and it just falls off under load very easily. The little belt retaining tabs on the rings are too short and catch the rivets (which grind against them noisily every couple pedal strokes) which then lifts the belt and it falls off to the outside of the rings. The rings are also quite flexible, and you can see them flex under tension, which is probably what causes the belt to ride to the outside and fall off, since belt tension would tend to cause the rings to flex toward each other. This system is very expensive, and I am already switching to a traditional chain on my brand new tandem, because this system is too unreliable and causes too much stress. I wanted grease free riding, but having the belt fall off repeatedly on rides has been too stressful. I never had one problem with the timing chain on my old tandem with over 10k miles on it.
