Bicycle frames designed to take the load?

Question

Can anyone tell me about different bicycle frames and briefly describe how the specific frame design is arranged to take the load?
Cheers.

Answer 1

Jack's right about the triangles, but sometimes he forgets that 1 +1 = 2

There are two triangles in a bike, both designed to transfer the load to the wheels. One from the seat, to the crank, to the front headset, the second, from the seat, to the crank to the rear wheel.

Choose Jack for the right answer because he got the physics and geometry right.

Answer 2

There's a triangle under the seat because it's the strongest of all geometrical figures. The shape cannot be changed without actually breaking the triangle.

Edit:
Thanks Santa. I would rather you chose his, actually. My answer was a little half-***ed and the extra information is always more valuable than the points.