Its not a bike, its a "quike" (four wheels). Actually it is something called a Nordic cross-skate, it is like roller skis but with larger wheels. You attach one to each foot. The commercial ones come with up to 8" wheels but I still get stuck in ruts on those which lead to wipe-outs so I want larger wheels. I had another question about the frame design here: Simple carbon fork extension for scooter if you want to see some pictures of the commercial ones.

I have made a couple designs and here is my current one, it has 16" wheels in the front and 12" wheels in the back. I am using the Schwalbe Ones with tubes in front now, these 16" carbon wheels with tires and tubes weigh about 500g which is still 100g lighter than the commercial 8" wheels so I am pretty happy with the weight. I am still fine-tuning this, it didn't have enough frame support so I had to make the forks bigger and thicker. I also hope to eventually get tubeless going, but the Schwalbe Ones are far too loose on the rims so I will need many rounds of rim tape.