Utility Cycling Technology: Fixed Gear Drives (Non-Hub Direct Rear Drives)

https://endless-sphere.com/forums/viewtopic.php?f=6&t=37207&start=300

This is the original way to motorize a bike. Gasoline motors used it with a small gear box to extend the range of the power. Electric motors have a larger usable power range. So a two sped gear box would work ok for a bicycle with 750 to 1000 watts. Maybe a three speed gear box for a moped at 1500 watts.

(Non-HubDirect Rear Drives)


https://endless-sphere.com/forums/viewtopic.php?f=28&t=57720&start=1025

Out of all the drive systems for an electric bicycle, a fixed gear is not just the only truly legal method, it is simply the best. Motors have a sweet spot where they operate the most efficient and coolest, and if your fixed gear runs at or very close to that spot your motor will last much longer with less heat.

If a hub motor was to be turned in to a mid mounted direct wheel driver, turning at a sweet spot of 500 RPMs it would take about a 2.77:1 gear reduction ratio to slow your 26” wheel down to about 14 mph. That should be enough to climb an 8% grade with 350 lbs (total combined weight) at 1000watts.

The majority of the heat that can damage the motor and controller comes from the amps of current. By choosing a system that has higher volts, you can achieve the same amount of power with fewer amps.

And if you really need a lower gear try using a two speed gear box, or possibly a two speed hub motor.

One gear set at about 10-12 mph and one at about 18-20mph you would have much better mileage. And some people claim “gears” rob too much energy form your drive train, HA! Unfortunately it is hard to find a gear box at an affordable price that is made for e-bikes.!

http://davincidrives.com/category/custom-electric-bike/

The wide torque band of electric motors, particularly the torque available at low RPM, eliminates the need for more than one gear.

Set the single fixed reduction gear at the highest speed that the available power will still be capable of driving your fully loaded vehicle up your steepest hill. Then if you still need a faster gear for less strenuous terrain, you can think about using a two speed gear box.

The wide torque band of electric motors, particularly the torque available at low RPM, eliminates the need for more than one gear.

http://davincidrives.com/category/custom-electric-bike/

And if you really need a lower gear try using a two speed gear box, or possibly a two speed hub motor.

The wide torque band of electric motors, particularly the torque available at low RPM, eliminates the need for more than one gear.

http://davincidrives.com/category/custom-electric-bike/

The only reason that you can’t buy a factory made bike like this is simply that people are mesmerized by high tech scams and want to turn their bicycles into illegal motorcycles. 20 mph is just not fast enough for them; nor is the moped’s 30mph. The fact that energy is going to become very much more expensive should change all that, but education is needed.

People claim that direct drive hub motors are so much more efficient than geared motors. Yet the best a hub motor can do is 75% efficiency. While a high speed high voltage motor like the Lightning Rods kit uses is up to 90% efficient, even with a very large gear reduction. Gearless direct drive hub motors are made for racing, not for hill climbing. They operate at a slow RPM and therefore can create more heat than they know what to do with; fast high voltage motors create more kinetic energy, and pump less amperage through the windings, thereby creating less heat!

The only thing that would keep a mid-drive system legal is a speed sensor connected to the controller and the wheels. But these are too easily bypassed accidentally. See why most electric bicycles are illegal.