Are fully steel wheels compatible?
No. Steel will be attracted towards Fliiiight's magnets.
Steel wheels are rare in modern bikes because they are heavy and provide a less reliable breaking surface. If you're not sure, run a magnet around your wheel. If the magnet sticks very strongly all over on the surface of the wheel, then you probably have a steel wheel.
Are aluminum alloy wheels with steel components compatible?
More common than fully steel wheels are aluminium alloy rims with some steel components. Wheels can have:
Steel spokes and spoke nipples
Steel spokes and steel spoke nipples are fully compatible with Fliiiight trainers.
All aluminium bike rims have a joint, which can be welded or sleeved or joined with a steel pin. Steel pins are attracted the magnet arrays, and are incompatible with Fliiiight.
Higher quality rims are more likely to be welded, but there are inexpensive welded rims available, and more expensive rims that use a steel pin. Not every wheel manufacturer includes this information in the product description, so we always recommend you check for yourself.
Steel beaded tires
Clincher tires can contain either a Kevlar or steel bead. A steel bead is attracted the magnets, and is incompatible. If you have a steel beaded tire, swap it out for an inexpensive folding tire with a Kevlar bead.
Folding tires are the most common tire type, and are typically higher quality. If you've ever changed or upgraded your tire, it most likely has a kevlar bead.