Continuing the discussion from Guide to Direct Drive Trainer Cassette Spacing:
A different way to describe this: The cassette has a range, a span from largest to smallest cog. The limit screws adjust the ends of the span, adding or subtracting to the smaller or larger distance of that snap, like using pliers and adjusting it for a larger nut. The barrel adjuster slides that span in one direction or another. If the cassette is the same type (11 or 12 speed) then adjusting the barrel will slide that up or down (left or right) on the cassette. If the bike is an 11 cog cassette, and you have that on your trainer, do NOT adjust the limit screws because if it works ont he bike already, the ‘span’ is set, it needs to be slid one way or the other. Adjusting the limit screws is asking for problems when you swap the tire back on.
BUT you shouldn’t have to do that at all, if the cassette is properly spaced. I’ve never had to adjust the rear derailleur, unless I hurriedly slapped on a cassette on a new trainer and didn’t take the time to space it properly. It’s not an art. You either have too many spacers, or not the right kind, or potentially something is really wrong on your bike. On all the trainers I own, I have not had to adjust the shifter at all, although I haven’t used every trainer out there, I would think that if you ‘have to’ adjust, it’s not set up correctly.
So if you are shifting off the large end of the cog, ‘into the Kickr’, you have too much space behind the cog, you have shifted the span outside of the span of your current setup. Putt some spacers out. Some cassettes don’t need the spacers supplied with a trainer. If it essentially undershifts, pull spacers out. It’s a pain, and can be messy, but some nitrile gloves, a cheap chain whip and a lockring wrench makes it easy to remove cassettes.
A chain whip, and it’s currently on sale.
And if you have a large crescent wrench, this will work. This one, with the large pin, helps keep the tool straight. This is a fancy one that doesn’t need a separate wrench to use.
Here’s a different brand, chain whip and a lock ring tool without pin and with pin. There are other brands out there that would work too. Taking it in to a local bike shop might not be a bad idea either. Get them to set it up. Some will do it for free too. Good luck…