ElectricScooterParts.com Support Center

Choosing the right gear ratio between the motor sprocket and drive wheel sprocket is the most critical part of converting a trike to be electric powered. A gear motor usually needs to be used with electric tricycle conversions because of the size of the wheels. If you want the trike to go slow then a small motor and small battery pack can be used (or a large battery pack can be used for a longer ride time).

I can run some gear ratio calculations to determine which motor and sprockets should be used. I just need to ask a few questions in order to run the calculations.

• What size tires are on the trike, or what is the diameter of the tires?
  
• What is the top speed in miles per hour that you want the trike to go?
• How many miles or minutes of ride time do you want the trike to have on a single charge?
  

We can design a system that will not over current the controller. So I can choose the right parts could you please let me know if the bike will be used exclusively on flat ground, used on flat ground and to occasionally go up light grades, or used on flat ground and to occasionally go up steep grades?

There is no advantage to using a 36 Volt 450 Watt gear motor over using a 24 Volt 450 Watt gear motor because they both have the exact same amount of power and the 24 Volt motor needs less batteries to operate which keeps the cost and weight of the kit down. So I made calculations and recommendation using a 24 Volt 450 Watt motor. I can make a kit with a 36 Volt 450 Watt motor if you prefer though.

I ran some gear ratio calculations for your electric tricycle project and found a good motor and sprocket combination for a 14.23 MPH top speed. Here is the calculation.

This gear ratio calculation is based on using our 24 Volt 450 Watt electric bicycle gear motor item # MOT-24450G which has a 9 tooth sprocket, along with a 27 tooth freewheel sprocket for the axle or drive wheel. We have a 27 tooth freewheel sprocket available with 1.375 x 24 left or right hand threads and we also have adapters to mount this freewheel onto a 14mm, 15mm, 16.9mm (for Schwinn Meridian), 17mm, 18mm, 20mm, 1/2", 5/8", 3/4", 7/8", or 1" axle. These sprockets use standard 1/2" x 1/8" bicycle chain which we can include with the kit.

For a 7 mile range on flat ground with occasionally light grades a battery pack consisting of two 12 Volt 15 Amp hour batteries should have plenty of capacity for the job. A 24 Volt 1.6 Amp battery charger is recommended for this size battery pack. A 24 Volt 500 Watt speed controller such as our item # SPD-24500B is a great match to the 24 Volt 450 Watt gear motor.

For a throttle I recommend using one with a built in key switch and battery meter such as our item # THR-105K. With this throttle no switch will will need to be mounted onto the bike so the kit will be very easy to install.

Drive sprocket choices:

• 27 tooth freewheel sprocket with 1.375 x 24 left hand threads.
• 27 tooth freewheel sprocket with 1.375 x 24 right hand threads.

Axle adapter choices (all axle adapters work with right hand thread freewheels):

• No axle adapter needed.
  
• Need axle adapter for 14mm, 15mm, 16.9mm (for Schwinn Meridian), 17mm, 18mm, 20mm, 1/2", 5/8", 3/4", 7/8", or 1" axle.

The only thing I need to know in order to make the kit is what type of drive sprocket and or axle adapter configuration you need, and if all of the other parts I recommended sound good to you or if you would like any substitutions made?

I was just reading over this post again and realized that the trike weighs 80 pounds, the batteries and motor will add another 30-40 pounds, and the trike needs to be capable of carrying around 300 pounds. With this much weight I think that a 36 Volt 650 Watt motor would be the best choice for a 10-15 MPH top speed. The 24 Volt 450 Watt motor is designed for a 250 to 300 pound load at 10-15 MPH. I will work on some gear ratio calculations for a 36 Volt 650 Watt gear motor and post them here when they are ready.