The ratchet hub is a beast, with an oversized 20mm female axle and collars instead of the more common 14mm ones found in rear hubs. Despite the large axle, they are still available with 9t drivers.
The driver, collar and bolt removed File:Http://www.gsport.co.uk/junk/9tooth/9tooth2.JPG The order of shims and spacers which fit into the driver File:Http://www.gsport.co.uk/junk/9tooth/9tooth5.JPG Assembled driver unit File:Http://www.gsport.co.uk/junk/9tooth/9toothd.JPG (pictures courtesy of )
A common mistake is to install the collars the wrong way around, causing the driver to bind. Remember the larger side faces out, and sits against the dropout. File:Http://i144.photobucket.com/albums/r184/20inwheels/Ratchet/IMG 0105-1.jpg File:Http://i144.photobucket.com/albums/r184/20inwheels/Ratchet/IMG 0104-1.jpg (pictures courtesy of Super Chief)