During the first mountain on the Tour, (Rockies) there is a level called "Mount Robson".
You are strongly recommend to wear armor for the event, but what you want to do is make sure you do not wear any. You know if you are not wearing any as your chance of survival will be 4%.
To be honest, I am rubbish at this game, but managed to get this first time, by just taking it ridiculously slow. What I did was quite literally keep pulling back with the left thumbstick to slow/stop my rider. So every 50m, when I build up some speed, i just slowed up.
This will not work all the way, as there are fallen trees you have to jump, but by going so slow you can see them well in advance, and as such, just speed up for that bit, jump the tree with A, then slow up again.
A boring method I know, but 25G is 25G!! Good luck!!