I’ve not ridden from Stirling, but suspect that bit is probably quite busy on the roads, with not many quiet options. I’m sure it’s fine if you just want to get there.
If you have a bit of time you could ride from Balloch, at the bottom of Loch Lomond. That’s an easy connect to Drymen and then Aberfoyle along NCN7. The Badger Divide comes down that into Glasgow.
You could also do train to Dunblane, ride to Callander and it’s a lovely ride into Aberfoyle along Loch Venachar.