A tall bike is an unusually tall bicycle often constructed by hobbyists from spare parts. Typically, two conventional bicycle frames are connected by welding, brazing, or other means, one atop the other.[1][2] The drive train is reconfigured to connect to the upper set of pedals, and the controls are moved to the upper handlebar area.
Alternatively, a bicycle can be built by inverting the frame, inserting the fork from the 'wrong side', flipping the rear wheel, adding a long gooseneck and tall handlebars, then welding an extended seat post tube to the 'bottom' (now the top) of the frame. This type of tall bike is made with only one bike frame and is often called an upside-down bike rather than a tall bike, though the seat can be pretty high, depending on the frame shape used. This type is safer, as there is less tubing between the rider's legs and dismounting in a hurry can be easily accomplished.
Finally, a tall bike frame can be made from scratch.[3][4][5]