Mostly, these 3 wheel bicycles are powered by pedals, but some of them use hand cranks. These can also be motorized by using either a small engine or an automatic transmission scooter motor or an electric motor. There are various designs of three-wheeled bikes such as Upright, Delta, and Tadpole. The Upright design is basically like a two wheeler with two wheels at the back and a front wheel and the rider sits on the frame and steers the tricycle through a handlebar that is connected to the front wheel.
The Delta design is much like the Upright, but the rider sits in a recumbent chair-like seat. In this case, the drive is through one or both the rear wheels, and the front wheel is basically for steering. The Tadpole design is also known as a Reverse Trike that has two wheels in the front and one in the back. In most cases, the back wheel is driven and the front wheels are used for steering. However, some tricycles have reverse features too.
Most adults and old people prefer the tadpole design as it does not involve too much physical effort and strain that are needed for normal upright bikes. These adult tricycles have a low center of gravity and are lightweight. Their aerodynamic layout is mainly responsible for their high performance level. There are some other variations of designs of three wheel bicycles such as having different sizes of the front and rear wheels and other unique features.