Keyswitch is just a keyswitch. What it controls and how it controls it is up to you and the hardware you choose. Most systems have built in wiring to turn the controller on with some form of switch, some don't; but you can use a keyswitch to enable or disable it whether it has specific wiring or not.
If you're going to use a specific type of motor, you just make sure to use a controller that says it operates that (and meets all your other requirements of current, voltage, features, etc).
For the power needs you'll have to define the actual terrain it will need to handle, because you can't do the math or simulate the power needs without that. If you don't do that, you'll have to just guess how much power it will take, and what gearing, etc., and then perhaps overbuy on power at motor, controller, and battery, and then hope that's enough to do what you want (if it isn't, you'll have to buy new parts with higher capability and then hope *those* will do it, and if not....).
If you don't know what the terrain actually is, you can install apps on your phone that will use the built in phone sensors to record the whole path of the worst parts you'll ever use it on, then go ride it or walk it, and use the data collected to see the worst-case parts' slopes and lengths, and base your highest power needs on those.
Youll also need to decide what speed you want to go up those worst-case bits, and if it is significantly lower than your normal top speed, and you will have a single-speed setup, you may need more power capability or at least cooling capability than you would otherwise, as running a motor slower than optimal at high load will heat it much more rapidly than if you ran it at it's optimal speed at the high load. Ebikes.ca has a simulator that can help you see how this works.
Here's one example simulation with a direct hubmotor (picked becuase it's already thermally modelled so you can see how the overheating works, and I didn't want to take the time to figure out gearing to use it as a middrive so I used a high voltage pack instead to compensate for the small wheels), for 45mph up a 15% slope at 450lbs. (I used that because it's likely the whole system including the bike is going to weigh more than 75lbs).
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
I copied the data table below. At this basic guesstimate (you can do better ones by working out gearing with custom motor specs to match what you might want to run on it, etc; the results you get can vary hugely based on all the factors you enter and parts you choose), it takes about 10kw to do this. YOu probably wouldn't be going up this steep a hill very much or for very long, so let's say that most of the time you only need the power to go that speed on the flats, which is only about 4kw, and only need the other power maybe 10-25% of the time. So, if you used a 72v pack, and need 10kw, that's 10000 / 72 = 138.9a, so call it 150A to ensure parts aren't stressed, so the controller in this case would need to be rated around 150A battery current limit, and the battery itself would need to be able to handle more than 150A (so it isn't stressed when the controller does draw that much, and so it can still do it as the pack ages) . 4kw at 72v is 55.6A, so anything that can handle the extreme parts can handle that.
Let's say you needed an hour's riding time, with 3/4 of it on the flats and the rest fairly extreme; you'd need 0.75 x 4kwh (4kw for an hour, but only 3/4 of one), or 3kwh for the part on the flats, and 10kw (we'll be nice and call it 8kw average for the extreme parts) for 0.25 of an hour, or 0.25 x 8kwh or 2kwh, for a total of 5kwh of battery. I'm not sure there is enough space in the frame for that, even if there's only battery in the frame and not motor or gearing etc.
If you don't have anything that extreme to go up, don't need to go as fast, or as long, etc., the numbers go down from there. If you have worse hills, you'll need more power, and if you need more acceleration at the higher speeds you'll need more power and possibly a higher actual speed capability even if you never go that fast.
| Graph | Syst A |
| Wheel Torq | 82.0Nm |
| Mtr Power | 9220W |
| Load | 9248W |
| Efficiency | 86.0% |
| RPM | 1074.2 rpm |
| Electrical | Syst A |
| Mtr Amps | 84.0A |
| Batt Power | 10716W |
| Batt Amps | 66.2A |
| Batt Volts | 161.8V |
| Performance | Syst A |
| Acceleration | -0.02 mph/s |
| Consumption | 238.1 Wh/mi |
| Range | 13 mi |
| Overheat In | 20 minutes |
| Final Temp | 159 °C |
Note that having a midmotor means you have (probably much) less space for battery if you only have battery inside the frame space.
