... Hi, I have recently bought the DAX 80 engine kit and am about to start fitting it to my bike. I have a problem in that I have a Shimano Nexus rear hub which is internally geared and also has a coaster mechanism. The diameter of this set up is 50mm so the rear sprocket that came with the kit will not fit. before I set about having this one altered which is actually quite difficult here in the Alpes without your own tooling. Is there a company where I can buy one of the shelf? Any help would be apreciated.