Something to consider, potentiality good torque & good top speed in one motor, front or rear options
http://xiongdamotor.en.alibaba.com/product/1582411347-220560510/Great_Power_Energy_Saving_Double_speed_BLDC_E_bicycle_Hub_Motor.html
http://xiongdamotor.en.alibaba.com/product/1582411347-220560510/Great_Power_Energy_Saving_Double_speed_BLDC_E_bicycle_Hub_Motor.html