A mountain bike friend of mine who is also off the trail for now has offered to let me try out her cross-country skis this winter in northern Indiana to see what I think of it. I am interested...but unsure how good an idea it is. This isn't down-hill of course, "just" cross-country.

How hard is this on the knees? I've a cranky knee that doesn't allow me to run due to an unstable patella ("runners knee"). Is this a real concern? I've been trying to research this but haven't been able to find what I am looking for. I know we have a lot of members who do this so figured I should ask here