My wife and I just purchased our first smart trainer and are setting up our Opus road bikes.
The Saris H3 didn’t come with a cassette so we purchased a separate Shimano 105 11 speed cassette. Pretty much matches our bike cassettes.
Tried both the medium and large through axel hub but are running into the same issue with both. On the small crank and largest cassette (lowest gear) , the rear derailleur rubs against the body of the trainer causing a chatter.
Don’t use the lowest gear that moves the derailleur closest to the trainer body?
Check the derailleur hanger alignment.
Use some kind of spacer to push the cassette out father. I’ve seen this done on a Tacx.
It’s probably just a design flaw and the combo of your bike and long cage rear derailleur aren’t matching up perfectly. Solution #1 is probably the most likely fix.
Mine does the same thing. Doesn’t really affect the performance on that gear, you COULD just sand down the plastic cover there to create some space if it bothers you. I’ve used the H1, H2, and H3 and all share this “flaw” but it’s yet to impact my bikes shifting inside or outside. I had the same issue with my 6800 and 8000 derailleurs
Thank you for the response. Great insight. I was able to remedy the problem by switching to my bike cassette. Guess the 11/32 was too big when my 11/25 came with the bike. In the spring I may get a longer rear derailleur and chain so I can use the 11/32 cassette. Need any advantage at 51 when climbing. Lol