Motorcycle with Pedal assist

[TroySmith80]

I'd like to make a light electric motorcycle somewhere in the 4 to 12 KW range and I want it to have pedals with torque and Cadence sensing. But there's really no reason at that power level to have the pedals integrated into the drivetrain. My power input would be trivial compared to the motor. I just want to get a little exercise and want to have a natural feeling bicycle experience similar to a nicely integrated mid-drive from one of the big bicycle manufacturers but at a much higher level of power in a substantially larger and heavier bike.
I guess this should be totally doable with something like an electric generator that the pedals are connected to that is used not to actually Supply any meaningful energy but just as a measure of input to be directed as throttle signal to the controller.
A few years ago there was at least one motorcycle like this, it was bigger than I'm interested though and for on-road use only. I want something for off-road.
Any tips or suggestions or places to begin research on how to create something like that? I would want it to be as light as reasonably possible and since I'm not really interested in generating meaningful electrical energy I don't need it to be a real generator, I guess it just needs to be substantial enough create some resistance and to shed whatever heat would be created by the up to maybe 100 or 200 Watts that a strong rider May sometimes put in.

 

[amberwolf]

There are quite a few pedal-generator threads, some of which actually lead to a design, most of which just discuss the problem / situation / options / etc. This list is not comprehensive and also includes non-relevant stuff, but some of them should be useful:

Search results for query: pedal generator

endless-sphere.com

The Electrom by Tigcross may be helpful.

This is one post in one of those threads by me

Rear Gear Generator

Hi! Long-time lurker, first time poster. A month ago I purchased a Class 3 cargo bike, rear hub with a cassette and derailleur. Overall I'm very happy with this choice. The bike, a Blix Packa Genie, has a cadence sensor and thumb throttle. I'll end up replacing the throttle with a...

endless-sphere.com

with some thoughts that apply to your needs.

The only similar thing I've ever seen built is simply connecting the pedal chain to a motor being used as a generator (or a generator designed for the purpose), instead of connecting it to the wheel at all.

Usually the output of that is fed via some conversion electronics to the battery, and is then typically called a series hybrid (vs parallel hybrid where the pedals have a separate power path to the wheel(s) via the mechanical drivetrain).


Sometimes there is adjustability to the load via the conversion electronics.

Those electronics may vary widely from system to system depending on what it is intended to do.

Just some ideas / thoughts:

A simple brushed DC motor/generator with brushed controller used as a PWM control (to select and/or vary the current allowed from the generator to the battery or load) is one of the simplest.

A more complex version could use a cadence sensor on the pedals to vary the PWM control to adjust the loading of the motor based on pedal RPM, or a torque sensor on the pedals to vary the PWM to adjust and maintain a continuous regular torque on them within the limits of the ability of the conversion electronics to vary the load. The limits are wider if using a resistive load to just waste the power as heat, but if the conversion electronics have a wide range voltage input and output, it can probably do it even by feeding the battery charge port.

 

[TroySmith80]

Thank you, I've done some searching but haven't found a lot, I'll check these out.

 

[fill]

Any idea of the power level you can achieve pedaling and how long do you estimate you can maintain it? Might be worth working out before you fit a complex system incapable of generating enough to support carrying its own mass, when a simple friction clamped crank while not contributing to the bike output wont cost much to carry due to its simplicity