pic: mousetrap car

[Not2B]

So, no one has mentioned one of the best mouse trap techniques ever...

Think about the force vector...and the direction the spring bar is traveling... and the direction the string is traveling.

For ease of design, you might want to keep the string perpindicular to the travel of the spring bar, so the force is transmitted to the string. Here's a little picture.

http://static.flickr.com/107/3134910...40497e.jpg?v=0

By the way - the CVT is an awesome idea. I did that for a mouse trap car in high school and it worked great! (We had to carry a can of pop on board.)

Good luck!!!