In standard guise, I know I can’t. I want to use a cheapy wheel on my turbo trainer but I can’t get a cheap 11 speed wheel, so was wondering if I could use a 10 speed and leave 1 of the smaller cogs out of the 11 speed cassette? Would my 11 speed setup still work as all the spacings on the cassette would be as per 11 speed, but my assumption would be that I would not be able to shift my derailleur into the lowest gear position due to the hub being wider on the 10sp. I’d have to use one of those nasty plastic discs to stop running the derailleur into the spokes by accident.

I do this with a cheap btwin rear wheel, i left out one of the middle sprockets i think 18t on a 105 11-32 cassette. Works ok and i don’t use the lower gears for training so no chance of the spoke damage for me.

Nice one! Thanks!

Slightly less cheap, you could try and find a 12t small sprocket designed to work with the lockring and swap it for the normal 12t sprocket in the cassette, then you only lose the 11t.

Is this fudging not going to cause the two cassettes to sit in different positions relative to the mechanism and therefore mess up the shifting?