So you want to use one of the big Colson wheels with the large bore, but you don't want to use a monster shaft. This is what you need to reduce the large bore down to something more manageable. These are custom built 6061 Aluminum bore reducers that were made to fit the Colson Performa wheels. These reducers are made especially for Robotic Combat standards
Outside diameter: .90"
Inside bore diameter: 5/8"