Are you allowed to cycle it?
If you are allowed, would you want to?
Or would it be unspeakably horrible and terrifyingly lethal?
I'm guessing No, No, and Yes. But I got playing with Map My Ride and noticed that a circular trip from Chamonix, via Martigny, to the Great St Bernard, down to Aosta then up to Courmayeur and so (?) back to Chamonix, would be 171km and 6563m, with two hors-cate'goire climbs in it (Col des Montets and the GSB). Quite a day out, even if you finished it by sticking the bike on the bus in Courmayeur like a normal person.
Update: wait a minute. I see what that second HC climb is. And why it's so steep... the software is computing it like you take the bike *over* the Mer de Glace rather than *under* it. Doh...
Still, definitely a two-Yorkie-Bar ride, even without the cycle up, and more pertinently down, the Aiguille du Midi
Post edited at 23:47