Thanks so much both of you. I'm still looking at alternatives for the expedition, and I'll drop a line as suggested to daviemore.
I do, as it happens, know the Glen Artney to Callander track. We used that in 2016 for day 1 of the overnight expedition. It may not be open to us this time, as there are new safety rules in place, but we'll see. If anyone has detailed knowledge of the trails west of Aberfoyle, that would be interesting. I'm trying to find out what surface or grade they are (green, blue, etc.) Looks as though some might be cinder forest tracks?
Bike Trossachs local knowledge
Re: Bike Trossachs local knowledge
For information about the cycle tracks around Aberfoyle speak to the guy at Aberfoyle Bike Hire. He was one of the people I spoke with today and he was very helpful.