Just a heads up if you fancy doing this, I would suggest not doing it the way it is described in the wild trails, Scotland mtb guide, it is totally bonkers to do it anti clockwise, up the fantastic Glen Derry descent, no payback for the slog over Bynack mor shoulder, the descent really is rubbish, numerous water bars frequently disrupt the descent on this upgraded section of trail. You will then have to ride/push up the great Feshie singletrack, sunblime to descend, if you do decide to do it this way, good luck.
I did it clockwise, the highlight being the Glen feshie singletrack and the Glen derry descent, which goes on for an eternity and is quite au natural apart from a few sections near the top, good enjoyed it.