It's been years since I did it so don't really remember - I used to do a loop from Glen Doll over and round Loch Muick and back again, and I did a couple of loops from near the Balmoral Estate once but can't really remember that loop. Don't think it was over 40 miles though.

This was all about 15-20 years ago now, on my rigid frame Trek 8000 - wouldn't dream of it now (though I still have it).