Motorcycle trike: The tadpole vs delta

A couple days ago I reviewed the Can-Am's flagship trike the Spyder. This got me thinking about about the different three wheeled configurations and any benefits and drawbacks they may have.

For those of you who happen to live under a rock, a trike is a three wheeled vehicle that can be mechanically or human powered. They are also referred to as three-wheelers, cyclecars, or tricars.

They most commonly come in two different configurations, delta and tadpole. Delta trikes have one wheel up front and two wheels in the back.  A popular example of this design is the Harley Davidson Tri Glide.  A tadpole or reverse trike have two wheels up front and one in the back, a popular example is the Can-Am Spyder.

Regardless of the configuration,  trikes in general have several advantages when compared to standard motorcycles and cars.   For one, they typically weigh less than a car and have smaller engines translating into better fuel economy.  Secondly, unlike a motorcycle or scooter there is no need to balance, as they sit up on their own.  So anyone who wants the fuel economy of a cycle but has difficulty handling a motorcycle might enjoy a three-wheeler.

In both of the delta and tadpole designs, the front or rear wheels can be either the powered and/or steering wheels.  Usually, in motorized trikes, the rear wheels are the powered and the front are for steering.  For the simplicity of this article we will use this configuration.  So what are the benefits and drawbacks of each design?

The diagram I included above (from Wikipedia) does a good job of illustrating one of the benefits the tadpole configuration has over the delta setup, braking and turning.  Any three wheel set up, triangle, is more prone to tipping then a four wheel car, or rectangle.  This is because the combined tipping forces at the center of gravity from braking and turning can extend beyond the triangle formed by the contact patches of the wheels.  Notice the wide base or contact patch of the two wheels up front on the tadpole design.  This makes it more stable under turning and braking.

Another benefit of having two wheels upfront is improved aerodynamics.  The lowest wind resistance, and thus increased fuel efficiency, is present when the vehicle is in a tear drop shape.  The wider front end of the tadpole and tapered rear end fits this description and can lower your wind resistance.

So is there any benefits to the delta type trike?  Yes.  For one, it takes less mechanical parts to turn one wheel which can reduce the overall weight.  Quicker acceleration?  Although I could not find any evidence to specifically support this conclusion, I will think that acceleration would be better.  Having a larger contact patch at the rear would in theory allow for more grip and less slip when accelerating.  Subjectively, I would argue looks.  Even with three wheels the delta set up holds more true to the classic motorcycle design.

So there you have it.  Some thoughts on trike design.