See the below links for a large collection of free roulette systems. You can also visit www.vlsroulette.com and www.rouletteforum.cc which have loads of free systems.
The best free system that works is explained in the video below:
This method is called visual ballistics, and often referred by casino staff as “advantage play”. If you really wan to know what works, it is wise to consider what the casino professionals themselves say. I’m not talking about some dealer that spins the ball and knows nothing. I’m talking about the people that design the wheels and are responsible for security – the people that are trained to protect the casino’s money. Any such professional will tell you that roulette can be beaten, but only in specific conditions.
These specific conditions and requirements depend on the roulette system being applied. A simplistic method inevitably means it will have more limitations. The system in the above video is simplistic, although it is used only to demonstrate a basic method that can beat roulette. You can learn more about more advanced methods at www.roulettephysics.com