Very observant, I do have the eZee geared hub. I have not had any issues with the motor over heating. On the other hand, I have had issues with the batteries. I purchased the eZee 36V 24AH flat pack. On the first big ride we did it blew an internal fuse on a fast climb. Opening the case I found that it had a 30A fuse and I had the max battery current programmed to 42A based on Grin telling me that the pack should handle up to 48 amps sustained. They seemed a little surprised with my findings and suggested that it was a limitation of the BMS and not the cells. Grin said that based on the fuse installed, that I could probably push a little past the 30A but suggested that I not exceed 35A (This does limit the max torque I can get). I replaced the fuse with a 40A and programmed the controller to limit to max of 35A. This has been working well until our last very hilly ride where the power died at about 12 miles. We started the ride with a pack voltage of about 27 V (or about 65% of max charge). It turned out that the cells had gotten too hot and the BMS went into thermal shut down to protect the cells. Full functionality returned in a few hours later..

The point of my rambling is that with a tandem, climbing will be slower which is resulting in higher battery and motor currents. I my case, the battery plant appears to be the limiting factor (both in terms of max supported current and thermal mitigation) - The hub motor has only been warm to the touch and we have not even gotten close to the 150C max rating. You may not need the Statoraide or cooling fins. (Maybe system performance is different for a single).

My next step is to use the Phaserunner application running on an old net book to log all the system parameters during a few rides and analyze the characteristics of when we are stressing the batteries. Depending on what I find I may modify the battery case such that I can increase cooling of the battery array, or I will design and build my own battery subsystem with a higher power BMS and cooling. One thing that is very interesting with the electric motors, is that it is more efficient and dissipates less heat the faster you ride.