Up until a few days ago I didn't know what a 'chain keeper' was. The chain kept falling off my Raptobike when reversing, or hitting big bumps. I suspect a previous owner removed said item at some point as they seem to be on most Rapto pics I've seen. After checking out the prices from terra cycle, (and me being the Bishop of Bodge) I thought I'd have a go myself. 1/2 hour later, et voila! It's made from aluminium, but I have some carbon wrap sitting around, so it seemed rude not to!