Solar-Powered E-Bicycle
A hub motor, a controller and a panel on a bicycle — and two small ideas about when the motor should be allowed to help. Built at thirteen.
This is the oldest thing on the site by five years, and it is here because of what it taught rather than what it was.
The build is what you would expect: a hub motor in the rear wheel, a speed controller, and a solar panel on a carrier over it. Nothing in that list is unusual, and none of it is where the work went.
The two ideas
The work went into deciding when the motor should help — which turns out to be the only question a bicycle like this actually has to answer, and the only part of it a thirteen-year-old’s pocket money can influence.
The first was an auto-switch: the assist engages on its own rather than waiting to be asked. The second was a speed-limit cut-off: past a set speed the motor is taken out of the circuit, which keeps the machine legal, keeps the rider pedalling, and stops the panel being drained to push a bicycle that is already going fast enough.
A patent application was filed covering both. The scanned papers are in my own archive, and I am not going to claim more about their status here than I can show.
What came of it
The Marathi news channel ABP Majha ran a segment on it in January 2014. That was the first time anything I had built was looked at by someone who had not been asked to look at it, and the effect of that on a thirteen-year-old is not something I can overstate.
The drawing above is a reconstruction rather than a record; the bicycle itself is long gone. What survived is the habit — find the one decision in a system that actually matters, and spend the time there.
Everything else on this site is downstream of that.