The best time of the year to tour southern Tuscany on bicycle is in the spring, from mid-April onwards until early summer, say mid-June. In July and August the climate becomes very hot (but dry), so bicycling can become difficult in the mid-day hours. Similarly, the autumn is wonderful until about early November.
In Argentario, for those who enjoy mountain biking, are very fit and not faint hearted, there is the dramatic 39 km panoramic road around the peninsula, 4 km of which is on a rough track with a number of potholes! It is well worth the effort, though, as the views are quite spectacular and there is always the promise of a fortifying glass of vino after the last downhill stretch into Porto Ercole.
For those who prefer gentler bicycling, lovely rides can be had on the flat sun baked earth roads in the shade of the Mediterranean pines on the Feniglia beach outside Porto Ercole. No cars are allowed on the Feniglia and you can bicycle all the way to Ansedonia, a distance of 8 km. Bicycles can be hired at the start of the Feniglia.