On the second floor there are cracked floors. When I try running or riding my BIKE, I fall through instantly.
Are you sure you're using the right kind of bike because there are 2 types of bikes and I think the one you need is the mach bike and you should hold B like you do when you're going up a slope.And just out of curiosity are you using a ds or a game cube?
watch the whole video you need a special bike first visit: http://www.youtube.com/watch?v=FWPvz5d4hoc second visit: http://www.youtube.com/watch?v=4LsEVztB3xE