Sheldon asks Missy to teach him how to ride a bike. However, in the earlier episode "An Entrepreneurialist and a Swat on the Bottom" you can see him riding on a bike to the bus station all by himself.
After the doctor puts Sheldon's X-ray up against the light it disappears a few moments later.
In The Big Bang Theory (2007), someone leaves a bike in the hall. Sheldon says that he would steal it to teach them a lesson if he knew how to ride a bike. Yet, here he is years before riding a bike for "11 miles that day."