I have a 7 speed hybrid Infinity Boss three 7 speed with a Shimano TZ21 14-28T Freewheel and am trying to figure out what I need to get this bike on a refurbished kickr core which I'm planning on buying. I've been trying to do research, but am still overwhelmed with figuring out what it's going to take to get this dang costco bike on the kickr core. I think that I basically have 2 options:
- Purchase a 7 speed cassette with a 4.5mm spacer to get it to fit a 8-10 cassette and then another 1.8mm spacer to get it to fit the 11. It sounds like to do this, I'll have to do some weird thing to file notches in the 4.5mm spacer?
- Purchase an 8 speed cassette, but only be able to use 7 of the cogs. I think that's how it works at least? It feels like the main appeal to going this route is that 8 speed cassettes seem more "standard", and I don't have to do the hacky filing thing.
Is there anything I'm missing here? And further, is there else I should consider when buying a new cassette, and is there any reason to get an 8-speed over a 7-speed or vic versa? For a 8-speed I'd be tentatively planning on purchasing something like a Shimano HG51 8-Speed 11-28T or a Shimano Alivio CS-HG200 7-Speed 12-28T (basically the first 2 shimano cassettes I found on Amazon).