It appears to me chains are often the achilles heel of spinners. They are always coming off in battle. On microCHIP I used a V belt (as used in pillar drills actually) because I wanted a little slip to protect the motor and other components. I used a 1:1 from an 18v driven EvoWarrior with two hefty pulleys. The belt was 10mm wide. On the latest microCHIP Im using an Astro which revs at 11,000 the ratio is 3:1, but Im using the same lucky belt that Ive had from the start. The weapon system has been microCHIPS most reliable part, I just wish the drive was as tough.