Congrats on the expat assignment!

Grenoble is a university town, so you should have little problem establishing contacts once you get there. A couple of ideas for you:

AVF (Accueil des Villes Françaises) is a welcome group for newcomers. In Grenoble you can get information about AVF at the Maison du Tourisme, 14 rue de la République.

Stop in to the mairie (town hall) when you get settled. Normally the mairie has a rack or table with pamphlets about all the clubs and associations in town. There are at least some hiking and skiing groups, probably choral groups and possibly many other things going on that you'll only really find out about by checking the displays at the mairie.

Depending upon the company you work for, there may be some activities for the employees through a company sponsored activities group.

Don't know when you're leaving, but should you arrive in Grenoble during the summer (July and August) don't get discouraged if things seem a little bit dead. All of France basically shuts down over the school holidays. Come September everything comes back to life and you'll find you have far too much to do all of a sudden.
Cheers,
Bev