I noticed the other day when freewheeling without being clipped into the pedals that the drivetrain is turning of its own accord, like a fixed gear. Is that likely to be the freehub causing that? Or something else?
Yes, but it's normal. It's only too much freehub drag if the top run of the chain is drooping visibly when you freewheel while holding the cranks stationary.
I noticed the other day when freewheeling without being clipped into the pedals that the drivetrain is turning of its own accord, like a fixed gear. Is that likely to be the freehub causing that? Or something else?