I think that the electric assist (Allen G, is that a StokeMonkey?) will do more to stress a hub than the extra torque from these drivetrains. The hub is solid. Good looking prebuilt, too, cman - hard to beat the price.
Val, thanks for the response. Interesting that these hubs are being used for other applications. There is a race circuit call Greenpower where several team are using them.
http://www.greenpower.co.uk/about/
Here is one from Team Bentley hooked up to a 24v motor.
http://www.bentleygreenpower.com/car/
