A delta trike has one wheel in the front for steering and two wheels in the rear where power is applied to the ground. Delta trikes can turn quicker (have a smaller turning radius) than a tadpole. Also, delta typically sit higher so entry and exit is easier for folks with mobility issues. Lastly, the best part of delta trikes is that they can be chained together to make not just a tandem but a train or riders connected to one another. This special feature is great for long tours where couples want a tandem but the option to detach and ride separately.