The style of recumbent tricycles with two wheels in the front and one in the rear is called a tadpole recumbent, because like a tadpole, the big end is at the front. Here is a very low slung tadpole configured recumbent, patented in 1975, and it has the rear wheel as the drive wheel, with the chain passing alongside the seat. The two front wheels are the steering wheels, and steering is by an underseat control. In this style of bike, the rider is way more comfortable, with no leaning forward, no saddle soreness, and no weight on his wrists. The wind resistance is also quite a bit less, which is why recumbents are typically faster than upright two wheelers on flat terrain, even though they are heavier. A really cool tadpole trike is the TerraTrike, and they have all kinds of information on their site at WizWheelz. A TerraTrike is shown below the 1975 tadpole.