The Sunrace is 10 and 11-speed. My Birdy came stock with the 10-speed 9-32, which I upgraded to 11-speed 9-36 for more range (there is also an 11-speed 9-32 cassette). Just after that investment the cassette freehub body broke, and I found out how weak the construction is. The SRAM XD(R) is stronger, I expect, since it's supposed to handle the higher forces you need for large wheels.