A buddy of mine managed to bunny hop the barriers you see above, on his mtn bike. Unfortunately, I believe he used more energy bunny hopping than he would have used to simply dismount and run...Also, on this same course, and many cyclocross courses, there are barriers at the bottom of the run-ups. This also makes it impracticle to bunny hop. Around here anyway, they seem to design the courses so that riders are forced to dismount several times each lap.