Smart trainer crunching, normal?

New Saris H3 smart trainer. First try and noticed it felt like the drivetrain was crunching a little bit. It’s hard to describe but its how I imagine it would feel if the chain or cassette were worn, or bottom bracket gone. To be clear, none of those things are worn. Indexing was adjusted.

Now tried with 2 bikes and it is worst in big chain ring and middle of cassette downwards. I read about chordal action. I’m wondering how un-smooth others find their smart trainers? Maybe this is ‘normal’?

Doesn’t sound (excuse the pun) normal. I take it you have lubed your chain? I had a crunching noise for a ride before I diagnosed a loose free wheel and tightened it up.

All degreased and re-lubed to rule that out.
It definitively feels more than sounds strange.

Check the cassette and make sure it’s snug.
What type are you running? Does it require a spacer, or has the smallest cog not seated properly?

I haven’t tried the H3, but the others I’ve tried are all buttery smooth with a good drive chain.

Tried a 105 11speed which doesnt need a spacer, and a 10 speed that has pins that fouled the spacer and wouldn’t go on, so got a new ultegra 10 speed that needs the Saris spacer plus the ultegra spacer. All seems tight and secure.

I have a Wahoo Kickr and experienced something similiar myself. I’m using the included 11spd cassette and a 12spd chain (I use my MTB on the trainer). I continually felt and heard a skipping/crunching sound. I was extremely lucky and found my quick link had “half” broke. Due to the fact that it was the inner side of the quick link that had snapped, I never noticed it when inspecting my chain/drivetrain. I replaced the quick link and its smooth as butter.
Another thing to note is the type of chain you’re using with it; the spacing and thickness is different on say an 8spd chain vs an 11spd. Best of luck!