Hire a bike at Katrine Wheels at the big Loch Katrine car park by the Trossachs Pier, and take either boat: the Sir Walter Scott steamer or Lady of the Lake modern cruiser one-way to Stronachlachar Pier. You can then cycle the 12 or so miles back to where you started, stopping off along the gently hilly Tarmac route to pick your way down to the water for a relaxing shore-side picnic. Prebook the ferry and bikes to avoid disappointment.
Brig O Turk, a village a drive east along the A821 from Loch Katrine’s Trossachs Pier is a wee foodie hideaway in the Park, with the Byre Inn and unlikely hut-like Brig O Turk Tea Room both serving good food. Both can provide some takeaway options. Otherwise, the beautifully set Pier Café at Stronachlachar is a lovely place to stop for a bite before cycling on your way.