Yes there is hard ground underneath the loose sand. The sand would be anything from 3 to 5cm deep with hard clay soil underneath. Between these areas it is fine. Doesn't seem to like the corrugations much either. I have noticed though that if I lean back so that there is more weight over the back wheel the bike is a bit more stable but not by much. I am sure that if large stretches of road where covered in loos sand I would get used to it, but there are just these small patches of about 2 to 3 meters long. You don't see them until you are in the sand and then the steering starts to get veeeery loose.