In GC there is A place Recuired With a Mach Bike how do I get Past it?
This Is the Place..
On B1F, the only way up to the upper half of the level is by using the Mach Bike to ride up a muddy slope.
So without the Mach Bike it is impassable. http://bulbapedia.bulbagarden.net/wiki/Granite_Cave ____ To answer you real question, those cracks can be ridden on with enough momentum, even if using the Arco Bike. The bike has various 'gears' that are an indicator of how fast the bike moves. If the gear (or momentum) is high enough, you can pass the cracks without falling through.