Hi, I have the above mentioned wheelset and am currently running a SRAM 11/28 OG 1070 cassette. Works great, love it. I assume I must have the R4 Shimano 10 Speed cassette body based on looking at the Easton Cassette Compatibility chart. My first question is: How do you know for sure which cassette body you have? Second question is: The R4 10 speed cassette body compatibility chart lists the DA 7800, 7900, Ultegra 6600, and 105 cassettes as being compatible.......what about the new Ultegra 6800? Is it compatible also?