I am arranging a trip to the French Alps around the middle of May, taking in the Stelvio amounst other things.
Would the passes be open and clear of snow in May??
Seeing as there are well in excess of 300 passes in the Alps, spread across four countries and an area the size of the UK it may help if you could narrow it down a bit.
I know you mentioned France, but then threw in a Pass the full length of Switzerland away, and far closer to Austria than France.
There is a Garmin Mapsource file floating around the forum somewhere with about 300 passes in it, maybe use that to plan out where you want to go.
This site has many Swiss and Austrian pass video's:-
http://www.bikecam.ch/karte.htm
And there is good info at
www.alpineroads.com, although it is not updated much the forum has a load of knowledgeable folk only too happy to answer questions (including locals)
Some good climate info and averages can be found here:-
http://www.weatheronline.co.uk/weat...=euro&LAND=SW®ION=0001&WMO=06759&LEVEL=160
This is for Andermatt which is bang in the centre of the Alps, but the temperatures can be very different between Andermatt high up on a mountain (2000M) and a town in the valley below (1000M or less)
Oh, and Climate is what happens on average, Weather is what you get on the day - they ain't always the same!
The book "Motorcycle journeys through the Alps and beyond" has about 80 trips and lists 322 passes, and splits up the Alps into 20 regions, each one could provide 3-6 days solid riding to cover all routes and passes.
http://www.voxprof.com/kota/default.html
I normally spend 2-3 nights at 2-3 locations with a few travel days in between, which is what you will need to do to cover some French passes and the Stelvio, I did a similar trip in 2010
http://www.ukgser.com/forums/showthread.php?t=247181
In 2011 we rode Route Des Grand Alps, which you could probably call the French Alps as it covers most the major / famous French passes. This route spans five chapters of the book if you rund down RDGA and come back up Route Napoleon and whizz around the Vercors, we did it in 9 days (plus a couple of days to and from the UK each way) but could have easily spent twice as long on the trip and not covered all the available routes / passes.
http://www.ukgser.com/forums/showthread.php?t=279972