A rear sprocket on those five spoke mag wheels. I have been thinking about getting one for my bike. After breaking out those spokes the thick ole mag spokes look good but what would a nine hole sprocket do on them I wonder.
couple things to consider.
1> you have to bend your frame to accommodate the rim. what they are using is a hydraulic brake mount on the rim so it will be wider
2. real small screws and only 6 of them on the mount. also your sprockets will have to be drilled to work with it