Consider hiring the road bikes instead of the hybrids, which have a narrow gear range and are quite heavy. We never came to like them, but they are fit for purpose...more or less.
Dining out can become extremely expensive in eurozone. There are shops in most places and the bedroom banquet or indeed the picnic is a great way to reduce costs.
Take ear plugs for the Stuart Hotel on the penultimate night. Least favourite place.
Go the the restaurant just down from Antonia's in Omni Cappella, is much better than it looks! Before that enjoy watching the men play boules in the church car park next to the shop...perhaps with a cold tin of something?
Do the long day one, well worth the effort - but beware being forced into a late start by the bikes being delivered on the morning of day 2 instead of the evening of day one - MOST annoying.
Be aware that they say they will only carry one piece of luggage between hotels. They took our two light pieces each, so it was OK but it was all a bit unclear for a while. I read the bit about the 15Kg max but failed to notice the single item clause. Seems pretty mean.
Don't go in via Sardinia to extend the trip into a two island holiday. Sardinia and Corsica have poor public transport and do not connect very well. If I did this again I would either go into Pisa and ferry to Bastia from Livorno, or fly direct to Bastia.
Don't expect to change money easily in country. Do it before you go!
Breakfast is universally nutritionally hopeless (bread, jam, juice, a biscuit). You will certainly need a good second breakfast with some protein in it .
Start early! Afternoons get hot.
Enjoy this cycling holiday, Corsica is a fantastic place, this is a fantastic not too hard route, and we think it was outstanding.
The guide notes were pretty good, bit not all of the distances were accurate. Often there was a 1 to 2 km difference, which can be a bit disconcerting if you think you have missed something.
We only missed one turning, last day - watch out as the 'road ahead' is the wrong one! AS you come into the village beginning with V, name forgotten, you have to TURN LEFT to stay on the right road. Is in the notes but a bit more emphasis may be needed for tired idiots...