Thought I'd graph a direct comparison of the electrical watts supplied into a motor and the actual motor output (watts) power.
Based on a 750w motor at full throttle ...


At 1mph energy efficiency is ~3% ... 97% wasted heat.
Flat line at low speed is the A, (= Amps), limit of the controller.
A lower Amp controller reduces waste at low speed without affecting higher speed performance!

Best ... response?
Pedal assist getting started ... and up to more efficient speed?

Data provided by ebikes.ca/simulator

Controllers are not rated in Amp Hour ..... and your graph is just as ridiculous.

I've always recommended restrained throttle combined with pedal assist, from a dead stop ...

For those incapable of throttle restraint, I recommend a reduced amperage controller.

Full throttle - 50A vs 30A Controller

At sub 40% speed, amperage, (effectively = throttle), is forcibly limited.
Peak motor output and top speed are not affected!

I thought the whole point of an electric bike is that you didn't have to do any work?

No, it's for some assistance when you need it, If you want an E-Bike so you don't need/want to pedal you need/should get a moped... JMO

Yes ... both of you ...
Something to consider ...
What do you expect of an eBike?
See - eaBike vs eBike vs eMotorcycle

Bicycle type, (largely aerodynamics), determines the amount of power to acquire various speeds.


Frontal area is not as much a factor as the shape of the frontal area!

See - Aerodynamics

Speed vs Range

Everyone likes more speed!
Well ... most everyone.

What most don't realize is the cost of more speed.
Pulled from the ebikes.ca simulator, I noted the various ranges supplied at different speeds.

Generic Mountain bike - motor only.
665w peak output motor w/48V 10ah battery = similar to a 24V 450w peak output eZip motor - pushed to 36V 675w peak output motor.

Anyway
10mph = 46 miles range
15mph = 30 miles range
20mph = 20 miles range
25mph = 13 miles range
30mph = 8 miles range

Wow! ... calculator - click click click ... Every 5mph increase in speed decreases range by 33%!

Most are shocked at the affect wind resistance plays.
Wind resistance is the major factor, but road load, tires, drive train etc. also contribute.

Makes me reconsider a lot!
Do I need 30mph capability? Nice to have it but ... don't need to use it! - OK! - Still a go.
Road Style bike with high pressure tires and crouched position? - Working on one!
Motor only, crouched behind an Aerodynamic fairing? Sounds almost essential - for sustained 30mph! - Battery pack mounted between bars and fork is a partial fairing. I'm sure I could easily enhance that!

Fortunately, I tend to cruise at 15mph, commute at 20mph with only very limited bursts nearing 30mph.

I'm even considering not upgrading (choke) my latest eZip Trailz LS.
(I use 3 eBikes + latest eZip, + building a road version and an eTrike ... also.)
OEM configuration is limited to 15mph in TAG (Twist And Go) mode and ~10mph in PAS (Pedal Assist System) mode.
Well, not upgrading, till after I run a range trial with my prototype 22.2V 40Ah pack.
I will add high pressure 1.75" tires for less rolling resistance and comfort seat and suspension post ... <15mph range trial might mean 5+ hours in the saddle!


A differing summation of watts required for a mountain bike to maintain various speeds.

*5mph = 22w
10mph = 68w
15mph = 163w
20mph = 333w
25mph = 601w
30mph = 993w
35mph = 1532w
40mph = 2247w
45mph = 3147w
50mph = 4280w
* from ebike.ca simulator

30mph requires almost precisely 300% the energy as 20mph.
Of course, it does not require 3x the energy per mile.
163w/15mph = 10.86wh/mile
333w/20mph = 16.66wh/mile
993w/30mph = 33.1wh/mile
Still 30mph require 2x the energy per mile, or ...
Same ~36V 10Ah battery ...
15mph = 30+ mile range or - 92.08 miles per kWh = 6 hour cruise time
20mph = 20 mile range or - 60.02 miles per kWh = 3 hour cruise time
30mph = 10 mile range or - 30.21 miles per kWh = 1 hour cruise time