Around 5-6 years old. First bike was a "curb special" that my dad overhauled and repainted. It was a 20" wheeled bike, white with gold accents. Learned to ride by coasting down the hill between the garage and the house and crashing into the neighbors carport.
First "real" bike was a Western Flyer in Red, had a couple of those, then had a few oddball beater bikes after that. By age 13 I was saving money and buying my own bikes, Schwinn's then, Motobecanes, Colnaglos, Fuji, Bob Jackson, Teledyne Titan....Raleighs, Giants...
Aaron
