Need for a transmission or nay?

Hello,

I'm thinking about building an electric bike, but as you know, there are many ways to achieve this, and the way the electric motor is implemented varies from ebike to ebike (hub motor, mid drive motor, etc.).

So my question is this:
When using an electric motor, is a transmission recommended or not? Why? (pros/cons of both situations...?)

This will help me decide which design to go for when building my ebike.

P.S. I'm new here so feel free to move this if it isn't in the correct subforum.

The more power you have, the fewer gears you need...plus...what are you going to do with this ebike?

A few years ago, there was a lot of discussion about two and three-speed transmissions.

A BBS01 36V mid drive? definitely a 9 speed rear gear cluster (or more?)

A BBS02 48V mid drive at 1000W? Maybe a common 7-speed?

A BBSHD mid drive at 1500W? Perhaps a three-speed, derailleur or IGH.

Lightning Rods mid drive at 3000W+? maybe a one-speed to the left side?

I'm mostly planning to use it as an a mean of transportation (meaning on-road use) instead of using a car (too expensive), but which would be faster than a bicycle. It also makes for a great toy to play with and have fun. I was thinking about getting a 1000w-1500w motor.

At that power level, consider a Bafang BBSHD with an 8-speed pedal drivetrain. Among bicycle drivetrains, 8-speed offers the best combination of robustness, low cost, low maintenance, plentiful gearing options, and fault tolerance. And a bottom bracket drive like the Bafang BB series gives you the most speed potential from a modest amount of power like 1000W.

Understand that when you apply more than human power to a bicycle to achieve more than human speed, you'll inevitably incur more than typical maintenance and running costs. At the same time, it becomes more important to stay on top of your maintenance, because high speeds have proportionally high consequences when things go awry.

Also consider a scooter, because it might be a better fit to your application in terms of cost-effectiveness and reliability.

I am a high school teacher and we build and race one man solar cars (800 lbs). Looking at the history of our event the cars average speed are 20-25 mph. They are all direct drive. Im looking into adding a 2 speed transmission. Can anyone offer any thoughts on the advantages, disadvantages and options?

Thanks

Here is a link to one thread, out of several on this subject.

"2-speed systems (R-D, dog-clutch or derailleur changing)"
https://endless-sphere.com/forums/viewtopic.php?f=28&t=8644

demanding off-roading sessions: yes
heavy cargo e-bikes that also need to go fast: yes
road bikes: no
commuter bikes: no