Road biking is good in and around the CHX valley if you do it right. May and September are brilliant; not much traffic, snow on the peaks, not too hot (although it’s downright bitter on some big descents, arm & leg warmers a must!).
I’ve never had a dodgy moment around here on the road bike until last week when I had a near-death experience with a white van man (blanc camion homme in these parts perhaps). Generally you’ll get locals (74 plates) swinging out wide to pass you, tourists & Swiss clipping your bars with their mirrors.
Couple of good rides that I’ve done in the last week or two from CHX:
-Col de la Forclaz (managed that in my lunchbreak)
-Barrage d’Emosson
-Combloux Loop
-Plaine-Joux
For the last two, and any other rides W of Chamonix (ie towards Servoz, not Argentière), most people drive/train to Servoz and go from there. The Vaudagne road, which is the only way out of the valley without going on the dual carriageway, is a horror story and possibly more suited to a MTB! So play the lazy card and go from Servoz.
The Colombières & Aravis cols aren’t far either.
I suppose I ought to plug the new book here, which has got all these road bike rides in, plus the MTB stuff: http://www.thechamonixbikebook.com