Check out Zechariah's "new" bike that we bought off of Craigslist for $25. I saw a little boy Zechariah's age riding this exact same bike at the park the other day and thought it should be time we taught him how to ride a bike.
He likes it, but hasn't really ridden it more than 5 seconds. I don't think that he understands how to pedal. I'm sure it will come in time. But, since I was on the topic of bikes, I thought I'd post a picture of his "new" bike.