Glen Sligachan is a great ride, I really enjoyed it. Did part of the well publicised loop from the Sligachan Hotel round to Torrin, missing out Strath Mor which I've heard is a bit of a bog/slog. Reckon it would work quite well as an out and back too, although you'd miss the fun descent from Am Mam down to Kilmarie. Mind you I'd have happily gone back down from Am Mam to Camasunary too, looked like it would have been a blast 🙂
I really don't think tackling the bad step with a bike would be much fun at all though.