You seriously should fear it on a mountain bike - the course is easy but the riders are demonically fast. I rode one of the races last year on my mountain bike and was being lapped by everyone and overtaken by 12 year olds. I don't think a suspension fork and 2.2 inch tyres helped, but the main problem is that they are seriously fit and probably do training, both of which I consider borderline cheating.
You seriously should fear it on a mountain bike - the course is easy but the riders are demonically fast. I rode one of the races last year on my mountain bike and was being lapped by everyone and overtaken by 12 year olds. I don't think a suspension fork and 2.2 inch tyres helped, but the main problem is that they are seriously fit and probably do training, both of which I consider borderline cheating.