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Motor compatability with home-built "Kyoto Cruiser" side-by-side tandem trike.

Hi there,
I'm looking to put an electric motor on my Kyoto Cruiser trike (see pic). The bike weighs about 80lbs. and when I factor in my weight (220) and my girlfriend's weight (140) I'm probably looking at somewhere north of 420 pounds. We want to use this trike on the local bike path which has a few moderate hills so adding an electric motor seems like a good idea. The question is how much power do I need to run between 5-20mph, which controller and how much battery for 20 mile range unassisted?
One of the advantages of the Kyoto is that it runs independent transmissions to both rear wheels via standard derailleurs and 3/4" axles. The left axle (passenger side) has plenty of open space so I am thinking of mounting a keyed hub on it, mated to a sprocket.
That would give me two motor options:
Option #1 - mount one of your 36-volt, 1000 Watt Currie motors (MOT-SD361000FW) with freewheel above the axle between the left frame tube and the wheel outrigger, and turn the axle via a 72-tooth fixed sprocket. That would run the axle at approximately one fifth of the motor's 2600rpm. Here is my main question. At 2600 rpm motor speed the 20" wheel is turning 21% of that, or 550 rpm. That's awfully fast (32mph) and I plan to do most of my riding between 10 and 20 mph! So...
  1. How much of that 1000 watts is available at say 50% of it's 2,600rpm (1250 rpm on the motor = 15mph bike speed)? 33% of motor's 2,600rpm (10mph bike speed)?
  2. Assuming that the motor can operate somewhat efficiently at those lower speeds, which controller should I use, what should I be looking for in terms of a battery to give me a 20 mile range at 33% power?
Option #2 - Mount one of your 36 volt 600 Watt gear reduction motors (MOT-36600G) in roughly the same location but mated to a freewheel hub and much smaller 14-tooth sprocket which would match output shaft speed of 480rpm to 336 rpm axle speed at 20 mph and mean the motor was running at optimal rpm of 3200rpm at that speed and 50% of optimal speed at 10mph?
Same questions apply:
  1. How much power is available on this motor at 50% rpm, how much at 33% (7mph) and would that be enough to move something that weighs more than 400 pounds?
  2. Which controller which battery would you suggest for a 20-mile range at moderate speeds unassisted.
Now we don't plan on riding 20 miles unassisted as I built the bike for exercise and we intend to use it for that. But it would be nice to know how much we need in terms of battery to go that far should the need arise.
Thanks in advance for your recommendations!
Mark 
Kyoto Cruiser from back       Kyoto Cruiser from side
Regarding your option #1, the 1000 Watt motor with a gear ratio providing a top speed of 32 miles per hour is not a good match. A 1000 Watt motor does not have enough horsepower to overcome the drag encountered at 32 miles per hour so it would not be allowed to run at its full speed and the amount of power that it could provide would be diminished. The motor would also be prone to overheating and burning out due to the gearing being too high for it.

We do not have any specifications on how much power the motor will produce at speeds lower then its top speed however from my personal experience the power of electric motors is significantly reduced as the rpm that they are run at is lowered.

Regarding option #2, the 600 Watt motor geared for a top speed of 20 miles per hour is a good match, however with a two rider cycle it will not have very much power for climbing grades on its own. It is better suited for a one rider cycle for unassisted hill climbing. However if it was used on a two rider cycle and the cycle had power input from the rider's pedals then the motor would provide significant assistance with uphill riding.

Again and unfortunately we do not have any specifications regarding much power our motors produce at lower than top speeds, nonetheless with a gear ratio that provides a top speed of 20 mph the motor will have enough power to operate the two rider cycle on flat to slightly inclined grades without pedaling, and up grades and inclines with pedal assist.


For a 20 mile range with a 600 Watt motor running at moderate speeds a battery pack made from three 12 Volt 35Ah will do the job. If there are many hills, or the cycle would be used at or near full throttle for the entire 20 miles, then a battery pack consisting of three 12 Volt 50Ah batteries would be a better choice.


Please let us know if you have any questions.

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