Here are just a few suggestions.

From Lodey Sails, the cycling is suitable for all ages and abilities to Mousehole (6miles) along the National Cycle Track Route 3, known as The First and Last Cycle Trail. West of Mousehole the cycling is tough all the way to Lands End (15 miles), don't miss Lamorna Cove or the views down to Sennen Cove from Route Number 3.

Away from Mounts Bay, there are hills to negotiate, but the views are always stunning.
The mining Heritage area on the North Coast and the multitude of ancient stone circles and sites are accessible on 2 wheels.
Keep to the 'B' roads and you will get to the best places with little traffic and no parking fees.
Take the Madron Road from Penzance to Morvah (6miles) to go from the South to the North Coast, head back from Treen via Newmill (5 miles). We can always advise on a route suitable for you.