[TheAdamist]

Motorcycles lean to turn at speed, the trikes generally can't and are prone to tipping or flipping.

I've only ever seen them in low speed parades though.

Not sure how the slingshots with two wheels in front and one in back are at speed, i generally only see those at low speeds in cities blasting music instead of trying to get anywhere.

[gorkish]

CanAm's tadpole trikes have a tilt/camber mechanism on the front wheels and can lean; it's not at all the same thing as a 2 wheeler but it's a light year better than the delta configuration.