I wanted to share my experience of setting up two bikes on one trainer since I did some searching to find if anyone else had tried it and couldn’t find anything
So my girlfriend are both avid cyclists. We both sold our fluid trainers and I picked up a Saris H3 in 2019 and have been loving it.
My girlfriend has been wanting to try Zwift for a while but she has a warbird with a 2x10 and I have a search with a 2x11 so I wasn’t sure how well it would work.
I figured since I only use TR and am always in ERG mode, and she wanted to use Zwift, which requires shifting, I would put the her 10 speed cassette on and just got the chainline as straight as possible on my 11 speed for ERG mode. Another note is that the 11 speed cassette spacing is narrower so an 11 speed chain will work on a 10 speed cassette but it would not be ideal to use a 10 speed chain on an 11 speed cassette. Not sure if it is possible but definitely not ideal.
I’ve been riding this way for over a month with zero issues and we have gotten pretty efficient at swapping our bikes out. It takes less than 3 minutes!
It may not be perfect but it was a helluva lot cheaper than a dedicated adjustable trainer bike.