Kuzan is able to ride a bicycle over the sea, thanks to his ice manipulating powers. He uses his powers to freeze the water in front of him to form a narrow track, which he can ride on. The bicycle itself, however, seems to hold no special properties.
Long Ring Long Land Arc
This method of traveling was first seen when Kuzan met the Straw Hat Pirates on Long Ring Long Land, after their Davy Back Fight with the Foxy Pirates. He was able to travel from island to island on his bicycle.
During the Timeskip
He has not been seen riding on the bike again, as he would go on to travel on Camel after resigning from the Marines.
One Piece Film: Z
Concludes non-canon section.