I like your subject, but it doesn't quite look in focus. Was there maybe a lot of dust or something? I like how you left some room for them to come into the photo, however I probably would have tried to go for a shot that was more action oriented, like over one of their big hill jumps or something? My host Dad in Australia was very into Motor biking... and he loved FOX! :-)
ever so slightly out of focus/ blurry / soft. hard to tell which bit of the shot is actually in focus (or is it a crop?) but you've captured some action well.