Mountain Biking in the Alps differs from riding cross country routes in the local woods in many ways. Generally if something goes wrong you are much further from civilisation and due to the unforgiving nature of the terrain the chances of something going wrong can be quite high. It pays off to be well prepared before heading out into the Alps with your bike. Having the parts and the tools to to make as many repairs as possible to your bike (and yourself!) is advisable.
While this may seem like a lot to carry for a day on your bike it can mean the difference between a break down being a minor inconvenience or it turning into a potentially dangerous epic.