If you define your complete usage profile, including terrain / weather (hills, wind, etc) as well as the speeds you need to go in various situations, as well as acceleration desired, and how far / long you need to do these things, you can use simulators like those at ebikes.ca to determine how much power you need to do the job. Then you can use that to find out how much motor, controller, and battery you'll need to do it.
A basic simulation made without knowing most of the required info:
Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...
ebikes.ca
uses a phaserunner and the GAA v2 standard wind in a 20" wheel, assumes total weight around 350lbs (probably be higher unless your 300lbs includes the whole bike already) and a 36v 26Ah battery.
This lets you go up to 19.7mph on perfect flat roads with no winds and no stops/starts for almost 50 miles. You can experiment with it to see how it performs in your *real* conditions and usages.
Graph | Syst A |
Wheel Torq | 10.5Nm |
Mtr Power | 362W |
Load | 363W |
Efficiency | 87.4% |
RPM | 329.7 rpm |
Electrical | Syst A |
Mtr Amps | 11.6A |
Batt Power | 414W |
Batt Amps | 11.1A |
Batt Volts | 37.3V |
Performance | Syst A |
Acceleration | -0.00 mph/s |
Consumption | 21.0 Wh/mi |
Range | 48 mi |
Overheat In | never |
Final Temp | 34 °C |
The motor itself doesn't control this. The user-interface and control system does.
So with the Cycle Analyst v3 and the proper cadence/torque sensor to replace your present BB unit (that your pedals bolt to), you can set it up to do whatever you want it to, if you are willing to spend the time to first read up on how the CA works (there is a complete info page and manuals on the ebikes.ca pages, and quite a few threads about systems using them here on the forums), and then create a setup profile for the CA that matches your needs and intent, and then tune the system once built to respond the way you want it to, it could make the bike like a "bionic" version of itself, where it is simply easier to pedal it.
I use the CA and just a cadence sensor to control my heavy heavy-cargo SB Cruiser trike, and it works very well. It would probably work even better with the torque sensor, but I have yet to get time to implement and tune that. So I use the thumb throttle for a "go button" in the situations where I can't start it naturally with just pedalling--most of the time that's not necessary, so the throttle is rarely used.