What for? After my travel insurance hit nigh on £400 this year I decided to get a basic policy and look at purely rescue options. Carre Neige for France and snowcare in Switzerland for skiing and I figured there would be something similar for biking. Austrian alpine club insurance seems to cover rescue, emergency medical costs and repatriation for summer activities in the alps. i haven’t looked into it too much but it’s fairly well reviewed, and not expensive.
Depends on how much you need the other end of travel insurance though, if you can wing it without the usual travel insurance for flights, delays, etc. French alps also you have the EHIC card to offset general costs so I’d be happy to go without.