Cassette Hubs
The advantage of BMX cassette hubs is, that the free-wheel drive is not on the outside of the hub, but built inside the hub shell. Instead of 13T to 18T on former freewheel hubs a BMX cassette hubs allows a smaller drivetrain down to 9T on your rear wheel.
Cassette Hubs FAQCassette Hubs stuff
Cassette Hubs FAQ
RHD / LHD
RightHandDrive or LeftHandDrive allow you to assemble your BMX Chain onto your preferred side. That avoids interfering your sprocket at grinding, for example.