Been catching up on posts so only just come across this.
Anyway, Corsica - small island but big adventures (and all that).
I was there some years ago - it's basically a mountain that rises out of the sea so there's no shortage of places to exercise your climbing legs.
My cycling there was limited - just hired bikes for a couple of days. (I was actually there for a hiking trip.)
I found the most spectacular scenery to be along the north west section (between Calvi, Ajaccio and Corte), especially along the coast road (near Calanches de Piana and Gorges de Spelunca). Lots of long switchback roads, along the side of the mountain with sea below. Very weird rock formations. On road the altitudes won't be too high - the highest peaks on the island are under 3,000m.
The southern area is quite mountainous too - less dramatic but still pretty. Bonifacio is a delightful fishing town.
The east is flat and green.
In terms of cycling this time of year will still be very hot - especially inland. Also, as there aren't loads of roads traffic can be heavy in summer, especially around the famous areas - note that Corsicans drive like Italians. (On another note knowing Italian will probably help you with the lingo. Corsu is very similar to Italian - some of them take offence to being spoken to in French !)
There is an official circuit of corsica that you can do by bike.
http://www.chez.com/bikeevasion/regle_corse.htm (in french)
You arrange it rather like you would to do the raid pyrenean - (write in to a local bike club, get the card stamped at various points in the island, complete it within a specific time etc).
You'll need time though - it takes in more than 150 cols !
Enjoy !
Maria
http://www.2wheelchick.blogspot.com/