Has anyone ever had metal flakes come from their cassette on a direct drive trainer? I’ve only done 3 workouts on TR on this bike, and I’ve just noticed this fine metal dust on the floor:
It’s a Tacx Flux, and I’m running a 11-28 cassette with a 1x bike (which normally runs wheels with an 11-42) cassette.
I don’t think it’s coming from the frame 
Is it actually metal or is it chain lube? Hard to tell in the photo.
I was about to say it looks like wax - is the chain waxed (or a wax based lube)?
Are you using a thru axle from your actual bike or an adapter QR? Look inside your dropouts and if you see a round ring, then you know where the flakes are coming from.
If actually metal flakes, your drivetrain needs lube.
If your drivetrain is waxed, it’s most likely excess wax that flies off. This is normal.
Deleted my earlier post - I originally thought it was frame related, but realised I am almost never on the smallest cog on the trainer. I don’t think it’s frame related.
Had another look again and the metal bit spray pattern looks to be drive train related
It’s really hard to capture it!
In answer to a precious question, it’s a 105 11-28 cassette. Will try some lube and report back!
Is the chain hitting the feet of the trainer? It could be plastic scraping off. The bottom of the derailleur cage looks extremely close.
iirc, the Taxc Flux did have an issue with clearance for long cage derailleurs.
Is their not this dist on the floor and far sidd of the trainer ( top right of photo)? If so, hard to think it is drivetrain related.
Or are you sure its definitely metal? Looks like on the cogs and a few of the clumped bits on the trainer like chain wax, what lube are you using?
It does. The Flux S can handle long cage derailleurs, but I don’t think the OG Flux can. If the OP is running a cassette with a 49t large cog on the bike when not on the trainer, I’d bet that’s a long cage derailleur and that’s potentially the issue.
It’s bike dandruff.
Try Head & Shoulders.
