Introduction: Electric Kids Bike

About: Design Technology Teacher at UWCSEA

This Instructable links to the E-Trike Activity and uses the same parts.

After running the E-Trike activity as explained in the above Instructable Link, I was left with a number of e-scooters that had missing parts, bolts, wheels, nuts, platforms etc. This would render the scooter useless bar the fact that I was still in possession of a good ‘newish’ battery, speed controller, motor and interface. The only issue being was that all these goodies were ‘trapped’ within the housing of the front wheel drive scooter.

Looking at what I had to hand, a collection of old kids bikes, i decided to combine the two: A child’s BMX and the working electrics of an E-Scooter.

In this Instructable, I will attempt to show you how easy it is to create a working e-Bike from ‘now’ quite commonly found parts.

The plan was to take a bike, remove the 'moving back parts', open up the housing of an e-scooter and extract the electrics, then transfer them to the bike to create a fully mobilised Frankinstein's monster.

Step 1: Step 1: Removing the Extras

Before anything, pump up the tires, make sure you have at least one inner tube that can hold the air.

The first stage is to remove the excess components from the bicycle, the back wheel, pedals, crank, sprocket and chain. You’ll need a couple of specialised components here, a decent Chain breaker, adjustable spanner and allen key is going to come in handy. When removing the bike parts, remember that the crank arm for the pedals should come off after the pedals otherwise your life becomes rather difficult.

The same crank arm nuts are loosened in the opposite direction to normal (righty tighty becomes righty loosey!)

Be careful when removing the brake cable, frayed cables always have a tendency to stab you under the thumb nail and ball bearing love to fall out of their cage and roll around the floor.

If you can't find a master link in the chain, you'll need to get your hands on a chain breaker, and use releasing oil to free any rusty parts well before attempting to undo.

I'm using 'Park Tool' tools, very nice to use with a great quality feel.. but you're paying for them.

Which-ever tools you use, what ever bike you have, just try to make it as light as you can, this'll save you energy and power consumption later on down the line.

Because the e-scooter will usually have an electronic brake and have it’s motor within the driving wheel, there is no need for you to keep the brakes, chain, pedals and sprockets.

Step 2: Step 2: Extracting the Electrical Goodness

regardless of which ever front wheel drive e-scooter you're using, you'll find the equipment located in the front steering stem. I'm personally using an Aleoca Scooter (100USD 2nd Hand) but I'd lost the back end so it was redundant.

You'll be looking to release the battery, speed controller, controls and Driving wheel. You'll need to make sure the scooter operates but you'll want to make sure the battery isn't fully charged (for safety reasons) these LiPo Batteries etc are VOLATILE, so carefully does it.

The stem will no doubt be protecting the insides very well so looking before touching will be advantageous. Remove any bolt and then LOOK INSIDE THE SCREW HOLES.. most of the time there's a grub screw hiding within. These scooters are usually made so that the parts can be salvaged, just not salvaged by the public. So you may need to create your own tools or look carefully for clues, what ever you do: DO NOT SIMPLY SAW THE STEM IN HALF, if the blade shorts the battery, you'll have a fire on your hands.

Once you've found your way inside, ease off the wires, the controls and battery. The speed controller will be attached, usually aluminium and with metal vanes running along side the surface. This is the heat sink. The speed controller will connect to the wheel via a much thicker wire than the rest, you'll have about 3 wires connecting to the e-brake (+,-,ctrl) and about 5 or so connecting to the throttle, 3 for the Hall Sensors if it's an automatic start (not a kick start) 1 for the GND and 1 for the 5v start..

There's a bit more information on this in my E-Go-kart Instructable.

Right, so now you should be GENTLY easing out the battery, trying to pull on the case not the wires, not forcing and certainly NOT HEATING up to soften the glue.

Once it's removed, lay everything out and begin the unhooking.

You're trying to remove the modular components from the wire harness, this should leave you with all the parts separated from each other, make a note of the connections because you'll be reconnecting later.

Step 3: Step 3: Transference

Take the throttle and attach to the right hand side of the bike handle bars. You'll notice that the photo I have is wrong, the throttle lever will jam up against the curve of the handle bar in this orientation. Leave the wires hanging, we'll look into fixing these later. The E-Brake goes to the opposite side of the handle, again leaving the wires hanging there.

Depending on the battery, it's shape and size, you'll want to work out where it can be fixed. Remember the heat sinks on the speed controller? These are a sign that a: it gets hot, and b: it needs air flow around it. So make sure you take this into consideration.

Step 4: Step 4: the Back Wheel

Chances are, the back forks are going to be further apart than needed for the new replacement wheel. I used a ratchet and wheel Nylon Brace to squeeze the forks together. This meant that they were uniformly pressed and I had the ability to loosen and tighten depending on the width of the wheel.

You could get away with a rope in a figure of 8 and the pressure from standing on the forks.

Ease the wheel in , the wire will usually be located on the left (this is important as the wheel needs to drive in the correct direction). Tighten the two bolts taking note of where the washers are on either side, (usually on the inside of the forks).

Step 5: Step 5: the Electrics

Now we move on to the 'iffy' part, the wheel should plug directly into the Speed Controller (ESC) the wire should be long enough and insulated enough not to worry too much about this. There will usually be a standard connector, male and female on the wheel side and the ESC side of the wire, and as long as you haven't chopped it off you'll have no beef.

The Throttle and E-Brake will most certainly be a different matter, you'll need to bridge the wires and extend from the handle bars to the chosen location of the ESC. I used an old Serial cable from a computer, the wires are colour coded and the male female of the wire connect in line. I cut the wire, spliced one end, stripped the individual wires and tinned the tips. You'll be working with some very thin connections, so the better you prepare the less stress and sparks you'll have.

If you can disconnect the battery at this point, you'll want to. Unfortunately I couldn't so it was a surgical procedure.

Tin the tabs of the connections from the ESC and Control modules (E Brake and Throttle) use the thinnest soldering tip you can, you'll want to tin the tabs without letting the iron touch the neighbouring tabs.

Once every thing has a layer of solder, you can proceed to join and solder, obviously remembering which colours joined to which. When you connect the serial cable, you'll need to flick the On switch and test it all out.

And that's pretty much it.

You should realise how easy it was to get something moving simply by connecting the parts of an e-scooter to it.

Remix Contest

Participated in the
Remix Contest