Ds can ride a bike?

I sent ds and dd to my friend's house for an hour of play last week. When I picked them up , ds said his friend (who is the same age as him) taught him to ride a bike. I didn't really think much of it as he doesn't have a bike at home and his older sister is possessive of her small bike with the training wheels. On Saturday, he was pestering his dad for a big bike without any training wheels and his dad caved in to the pressure and bought him a bike much bigger than dd's. They had to assemble it first which took a while and his dad had to go out and buy a specific tool. Then I didn't get to see him in action outside as I went upstairs. Well, today the dad and kids team were all geared up with their bikes to go to the park while I went to a local store hoping to buy some halal meat. However, it turned out that my fave store with the friendly family staff had closed down. :( So I went back to the park to see dh and the kids in action. I asked dh if ds could really ride a bike and he said yes. It was funny to see ds riding a bike which was a lil big for him. His legs were too short to push start it so we had to help push it before he could ride it. Dd on the other hand, was riding a bike which was meant for her when she was around her brother's age. I am amazed that they could do it at their age and especially ds to learn how to ride a bike from his 5yo friend who I think just got the hang of it recently (but whose siblings seem to be quite proficient bike riders as I sometime see them either walking or riding a bike to and fro school.)