I wouldn't know how to grade a track for a bike, however I will try and give
you some indication, you could get an average car to Red Bridges (NO005869)
then a land rover (with out needing diff lock) to Geldie Lodge. And I doubt
you would need touch the ground with your feet on the stalkers path from
Geldie Lodge to NN925857, after wich its peat bog country! I left the bike
at Geldie Lodge as I was returning via "Corrie Seilich"
Note, the crossing of the Geldie Burn at Geldie Lodge may become impossable
if in spate. As you can see from the pics I was there on a good day, and I
took the socks and shoes off and waded accross, knee deep!