The first three reasons to ride a trike is Comfort, View, and ease of use. A forth might be that they are a great destination machine. When you ride to say a bike race to watch, you have your own lawn chair to set in, in comfort. You dont have to set on on the ground. Or maybe the fact you dont have to wear really expensive cycling shorts, to protect you from your bike seat. I for instance wear $15 rugby shorts, riding my trike.