When in Fort Bill, go up Glen Nevis by bike. You will cross the river by the Polldubh waterfall, under a mass of crags where I used to do a lot of solo climbing. That stretch is where Hogwarts is set in the films. As the road climbs, it comes to a dead end in a turning circle with a huge waterslide coming down the hillside. Lock up the bike and put on your walking boots, and follow the path through the spectacular gorge (easy walking) until it opens out by the Steall waterfall (In the film Excalibur).
Keep walking. The path goes on a very long way, so go as far as you want, with views of the Aonachs and Stob Ban, and herds of red deer disappearing over the hillside as the stag watches to see where you are going.
Wonderful scenery, easy walking, simple cycling.