Are there any free or low-cost physics simulators that are easy to use? Software where I could, say, design a bicycle with two wheels, give it forward momentum, and expect it to stabilize and stay upright due to the computed laws of physics? It doesn’t have to be super-accurate, just enough to give a general feel of how things in motion will behave. Ease-of-use is a big plus.
(I’m asking because I’d like to experiment with different designs for home-made bicycle trailers.)
The closest thing I found was Garry’s Mod, a physics game/sandbox that uses a commercial physics engine… however, the bicycle videos I found basically cheated by turning the bike into a four-wheeled car with two invisible wheels. I’m not experienced with it enough to know if it’ll stabilize a properly modeled bicycle.