A good starting point is Zennor. The Tinners Arms and The Old Chapel Backpackers provide watering holes at the end of your circuit. The Tinners Arms does pub food and a modest selection of beers. The Old Chapel Backpackers cafe does pizzas, teas etc. as well as providing accommodation.
I recommend doing the route anti clockwise.The climb out of Zennor is steep so walking is a good option if you are not fit. This is probably the most strenous part of the ride. You are soon on the top of the moors of Penwith with views over the Atlantic and the English Channel. Descending the Try Valley Mulfa Hill with it’s with Mulfa Quoit is on your right. When you enter New Mill you turn right and start back towards the the moors. At the top of the climb you find abandoned cottages and engine houses, views of Mulfa Quoit and St Michael’s Mount you reach an engine house on your right with a track leading off in front of you. Take the track and then bear left going towards Greenbank “Ding Dong” engine house on the skyline. On your right you are passing “Nine Maidens” stone circle and just off in the valley is the Men an Tol. Greenbanks “Ding Dong”provides great vistas and shortly after you meet the Madron – Morvah road.
A worthwhile detour is to turn right towards Morvah and visit Lanyon Quoit. Further down the road is the turning in to the Men an Tol. Retracing your route you you enter Madron and just before you turn right is the village store. On the other corner is the village pub. The next place of note is Trengwainton gardens owned by the National Trust. After crossing the the Penzance – St Just road you dip into the valley which is the top of Drift reservoir. On your left is the rear entrance to Trewidden one of the hidden fern tree gardens of Cornwall. The route then takes you to the north coast, before dropping into St Just. You will get glimpses Land’s End, the Wolf Rock lighthouse and on clear days the Isles of Scilly.
A good time to cycle the coast road between St Just and Zennor is after the evening West Cornwall rush hour ! A MUST detour in Botallock is to visit Botallack Count House and Botallack Mine – Botallack Mine – Botallack Mine – Botallack Mine set at the bottom of the cliffs. After this a good pit stop is the Field House Cafe in Botallack prior to tackling the easy ride back to Zennor.