I am shopping for a new trainer. Zwift hub looks and seems the one I want. I have a 12-gear SRAM. Zwift Hub is sold out on the 12-gear cassette. Can I use 11 gears zwift cassette, or can I use my 12-gear cassette on the Hub?
Most likely your SRAM 12 speed system has an XD/XDR freehub body (minimum cog size 10 teeth). The Zwift Hub has a Shimano Hyperglide freehub body (minimum cog size 11 teeth). A SRAM 12 speed XD/XDR cassette will not fit on a Hyperglide freehub. The SunRace 11 speed cassette from Zwift will probably work badly. The SunRace 12 speed cassette from Zwift will probably sort of work, but not perfectly with SRAM, because it has Shimano 12 speed spacing. The ideal solution is to get an XD/XDR freehub for whichever trainer you buy, so you can use a real SRAM 12 speed cassette.
You might be interested in this other recent thread on the subject
Thank you Paul , Got it . Change the Hub and I can add my own cassette to the Trainer . That looks like a good solution.
So the zwift own 12 gear is not compatible with sram group-sets ? Did I get that correct ?
SRAM and Shimano 12 speed spacing are not identical, so there’s no such thing as a cassette that works perfectly on both. The best you can hope for is that it’s pretty close and works OK. For some people that might be adequate, but if I had a SRAM 12 speed bike, I would not want to use a cassette with Shimano spacing.
Also, if you use the 10 tooth cog on the SRAM cassette, you won’t find it on a Shimano compatible cassette because the freehub body won’t allow it.