0Jack A Lopez 10 years ago The power transmitted through a chain drive is equal to the tension in the chain multiplied by the speed at which it is moving. In SI units this is force in newtons (N), multiplied by speed in meters per second (m/s), to get power in watts (W). Also note that the speed at which your chain is moving is the speed at which the outer edges of your sprockets are moving, and the formula for that is v=ω*r, where ωis angular speed in radians per second, and r is the radius of the sprocket in meters. There is a specification for the maximum working tension for #25 roller chain. According to the Wiki article on roller chain, this max working tension is 140 pounds, or about 620 newtons. http://en.wikipedia.org/wiki/Roller_chain#Chain_standards Multiply that number by the speed at which your chain is moving in meters per second, and that's your answer for the maximum power you can transmit.