Shimano 12-speed bike compatibility with Elite Direto XR

[tonyadams]

Hi everyone,
I’m Tony, and I’m having a compatibility issue with my indoor setup. I’m using a 2022 Trek Émonda SL 6, with Shimano 105 Di2 12-speed and the standard 11-34T cassette. I recently bought an Elite Direto XR, and I’m having trouble getting the bike to sit correctly on the trainer.
The rear axle seems to fit, but when I tighten everything up, the chain doesn’t line up properly with the cassette. The derailleur also looks like it is sitting slightly too far out, and shifting across the cassette is pretty rough. It works reasonably well on the road wheel FNF, so I don’t think the derailleur itself is the problem. I’m wondering if I’m missing a spacer or using the wrong freehub/cassette setup for this combination. Does the Direto XR require a specific adapter or spacer when using a Shimano 12-speed 105 cassette? I’d rather get this sorted before I start adjusting the derailleur, since it normally shifts perfectly on the bike. Has anyone here used a Trek Émonda with Shimano 105 Di2 12-speed on a Direto XR? Any advice on the correct cassette and spacer arrangement would be appreciated.