Depending on the frame, drive, rim and brake system another hub is required. For most hubs, the so-called rotor is changeable. This is the recording for the cassette. With this system you can use many hubs with both Shimano, SRAM and other compatible cassettes. Also different axle systems can be adapted in most cases. This allows you room for later conversions. Other choices include spoke type, hole count and color, so finding the right rear hub is not always easy. Our support is happy to assist you. Just ask.