My rear aluminum sprocket broke apart. This is the 1st time I have seen a sprocket do this. I think I only had about 6 months of use on it, though I bought it in April 2014 (It was on my shelf for several months before I installed it). I just ordered a Sunstar Z works (or something like that), and don't think I will ever be buying a Supersprox again. Fortunately, it broke apart while I was going slow and we were on a gravel road segment accessible by truck. It would have really blown if I had to push it out of the desert.