Miamijim is right about mixing. The cassette that I am now using (12, 14, 16, 18, 21, 24, 28, 32) is made from 3 different sets, a Shimano (12-23) for 12, Sram #1 (11-32) for 14, 16, 18, 21, Sram #2 (11-28) for 24, 28, and Sram #1 (11-32) for 32. All 3 cassettes were 8 speed, so cogs and spacers were all same thickness. Since neither of the Sram cassettes lowest 3 gear were on a spider, I simply separated all 3 cassettes. One had 3 long screws holding it together which I removed, and 2 had 3 long rivets which I dremeled the heads off and removed them. I did not have to use any thing for the new cassette. I simply put the cogs and spacers onto the hub freewheel. It is the best shifting cassette I've ever used. I would not want to have more than a 4 tooth difference in the cogs. I'm also using a compact crank (50/34). I replaced the 53/39 crank on my 1996 Trek 5000 OCLV. The front derailleur is the original Shimano, but I replaced the rear derailleur with a Shimano RD-M580-SGS (Long Cage). I can use all cogs with the 50T Ring without chain rubbing the front derailleur, and all cogs except the 12T with the 34T Ring. Cross chaining is not go for chain or gears, so I stay away from the 28T & 32T while in the 50T Ring, and the 12T & 14T while in the 34T Ring. That said all shifts are rock solid and instant no matter what Ring-cog combination. You will also need to get a few good bike specific tools. Hope this helps. Good luck, and don't be afraid to try things. You can always work it out, and the guys on this forum are the best, that is how I learned a lot.