Starting from the E-bike hire depot at Rothesay pier take the B 881 south and immediately turn right to join the B 878. There is a 70-metre ascent over the first mile and a half to Via Point 2. That's the highest point of the ride. Greenan loch is on the right. The reward now is a lovely scenic descent (mostly!) of three and a half miles (forking right on the A 844) to Ettrick bay. Excellent views coming into the bay. Cross the bay (another flat mile on a cycleable track - but no tarmac) to the tearoom. Via Point 4. [6 miles]

At the tearoom, join the B 875, where there is a tarmac roadside cycle path ("The Tramway") - but Street View shows several nuisance gates, so I suggest sticking to the road.

A steady easy up-and-over on the B 875 for just over 1 mile until the junction with a service road on the left at The Manse (look for the cemetery) is reached. Take this service road for 1 mile - it's slightly flatter than the B875;  the track's surface quality is rough, but manageable.

Rejoin the A 866 briefly at the T-junction, turning left at Via Point 6 to go round the corner for the lovely views of loch Striven and the hills on the Toward peninsula. Look for a track on the right that goes down to the coast and photo opportunities at Via Point 7. [9 miles]

Return to the A 866 and turn left onto the A 844 heading round the bay towards Port Bannatyne. Bear left on the cycle route network at Via Point 8 and follow the coastal road to Ardbeg [12 miles] and then rejoin the A 844 for a flat coast run (apart from one very short climb at Via point 9) back to Rothesay [13.3 miles]