[Alan Anderson]

Originally Posted by Conor Ryan

But if your cim's are running hot, you can always add one of these: http://store.nextgenrobots.com/products (hint, use some thermal paste, its legal), or just a couple of fans.

Unless you can fill the CIM itself with some sort of thermally conductive (but electrically insulating) fluid, putting a heat sink on its case is less effective than you might think. The power is dissipated in parts that have very little ability to transfer the heat to the outside. To make its way to the outside, most of the heat needs to go through the motor shaft.