I have not used NCN 7 or any of the off road tracks in that area. But, we spent a very pleasant weekend away at Callander and cycled many of the roads in the area. As Stirlingcripin has stated, the route around Loch Katrine is very beautiful and almost traffic free and if you have the time, well worth the effort. The 2 road options from Aberfoyle to Callander are fine, personally I would choose the northern route as in my experience it seemed to have less traffic on it, but we did a quick loop around Dukes Pass and it was attractive and pleasant. Heading north from Callander on road is much less fun. The A84 is very busy and not cycle friendly. The route to the west of Loch Lubnaig has a tricky downhill off-road section that I would not recommend for a road bike. On the day we wanted to head north, we popped the bikes in the car and drove to Killin to do a loop around to Pitlochry on some stunning back roads. Good luck - hope you enjoy it.