[MFS766]

We ran into a similar problem with our roller too. We had two fisher price (way overpowered) roughly 9:1 gear reduction to a roller 1.5 inch in diameter. We used polycord pulleys. The roller was covered in rubber, so we would stall the motors or shred the polycord due to slippage. In fact, our roller would chew up soccer balls way too much.

I see two solutions:

1. We reduced the friction for the roller by using a pvc pipe. We also found the fabric from the bumpers and the rug material the arena are very good. Despite our high speed/low torque, we had excellent control and could even spin our robot in a circle. Also, its a lot nicer on the soccer balls.

2. If you really need more torque, try reducing the roller diameter without reducing the final pulley. This will increase your gear reduction. We couldn't do this because our roller is also our final pulley.

What is you material and diameter of the roller? I ask this because we also found that roller tangential velocity is more important than the rpm of the roller. I hope this can help. Best of luck.