Yes, this is a very simple idea. You are not accounting for the many detriments you do not know about or think about. Sorry.
- Bearings take away a small amount of power due to the friction we can't entirely eliminate.
- Chains take away a small amount of energy due to the friction we can't entirely eliminate.
- There are other parasitic avenues which expend energy that does not contribute to forward motion, even if you don't know about them and I don't list them all.
Everything you add - more chain, more gears, more bearings, more magnet cogging, more back-EMF from the electric motor - ALL of it adds to more loss compared to a machine that does not have them. That is, compared to the basic, manually pedaled bicycle.
Did you know that an electric motor also acts like a generator? I did not write that an electric motor can instead be used as a generator - I wrote that as it is being powered as a motor it is also acting as a generator AT THE SAME TIME - this is back-EMF and it is a resistance that produces energy as heat which means a loss of the energy that is put into the motor which slows the motor. A motor that has no load on it's shaft does not continue speeding up and speeding up - it reaches an equilibrium and does not spin faster. This means that the energy put in is balanced by the energy leaving - even though there is no load in the sense that we are thinking of. The energy leaving is due to bearing losses, air friction (a wind is produced), and back-EMF producing heat. An imbalance in the motor will produce energy loss as the vibration flexes whatever the motor is mounted on, resulting in, you guessed it, heat.
ALL of this energy comes from your body in your proposed approach. And it's ALWAYS more energy than without the extra bits you are suggesting, so you will ALWAYS need to put in more energy than if you just ride a bicycle without the extra generators, etc.
Everything added brings its own small-or-large loss to add to the original, simple bicycle.
The stored energy of a battery can be used to overcome this and more, resulting in a vehicle which requires lees human power to travel. A solar panel can provide the excess energy when the sun shines.
Feel free to do your experiments. You'll learn that the actual drawbacks are real and you'll learn what can be done, as opposed to what the mind can conceive when it does not know what the situation actually is. If you succeed, we'll all be happy, so make it happen.
