The main features of this bike are that we used an electric hub-integrated motor, and we used the front fork as the battery compartment.
metalwork and assembly: saul
battery mounts: dan
Step 1: Parts!
These hub-motors are standard equipment on the Zappy3 Electric Scooter (http://www.zapworld.com/products/zappyIII_scooter.asp). the entire zappy scooter is about $500, you can scavange everything you need from one of them, or you can order just the hub-motor and electronic controller from Zappy as spare parts, which will run you around $250 i think. The zappy scooter works great, but 3 wheels is SOOOO lame.
The zappy motor is 36V, 250W, and their controller has a key-switch and variable-speed thumb-trigger. By their specs, you'll get about 12 miles on a charge, at a speed of about 12 mph - although there are plenty of options for increasing those numbers.
Step 2: More Parts!
Batteries! the Zappy3 scooter uses a heavy, ugly and pollutin' lead-acid battery: 36V, 10.5Ah capacity. We switched to rechargeable NiMH batteries which are lighter, environmentally much better, and because they let us do our second stealthy move: hide the batteries inside the fork! NiMH D-cells have right around 10Ah capacity, so we used 30 D-cells to get 36V. we got our 10Ah D-cells from www.all-battery.com for about $6 per cell. make sure you check the capacity of the cells, as there are some super-cheap D-cells out there with much lower capacity (they just stick a AA inside a D-cell body!).
- 4130 steel tubes for the fork: 1.50" OD, 1.37" ID, 50" length. Mcmaster-Carr part 89955K67. The tube ID is the constraint here, anything between 1.35" and 1.40" is ok. the ID needs to be sized so that D-cells with an extra wrap of tape around them will slide in easily but not be loose.
- monster sissy-bar handlebars. i don't know where we picked these up, but there are places on the web selling them, and also banana-seats if you want one of those.
- 16ga steel plate, 12" square is enough
- Plastic tubing: 3 feet length of rigid plastic tube with 1" ID and an OD of 1.3 to 1.35 inch (we used 1" PVC schedule-40 water pipe from Home Depot). also, 3 feet of rigid plastic tube with 1" OD and 0.75" ID (we used nylon tube, mcmaster-carr part 8628K66)
- springs: 4 stiff metal compression springs with OD 1", length 3.5". mcmaster part 9657K142.
- axle dropouts: we used 2 big square nuts, the nuts are 2.4 inch or so on a side and about 3/16" thick.
- 4 plastic soda bottle screw-caps (1" ID), 4 brass #10 bolts 1" long with nuts, 2 steel #10 bolts, 2" long with nuts, 3 steel 4" compression-tube clamps. 4 pennies, wire nuts, cable ties, wire, crimp connectors
Step 3: Tools!
MIG welder, hacksaw, angle grinder, drill.
Step 4: Wheel Dropouts
Step 5: Weld Together the Forks
Step 6: Head Clamp
the head clamp has two short sections of split steel tube. these have an ID sized to just slide over the main fork tubes, and then a pipe clamp squeezes them together to lock down the position.
Step 7: Test Mount the Forks on the Bike
Step 8: Battery Mounts
- wrap each D-cell with electrical tape or shrink-wrap, they will be jiggling around inside the metal fork when you ride, and you want an extra thick insulator between the cell and the tube. if that insulation wears through, you'll short-out the pack and explode it.
- to make a good electrical connection on bumpy roads and to reduce damage to the batteries, the mounts are spring-loaded on both ends.
- the plastic tube-within-tube-with-bottle-cap setup is to hold the springs and contacts in position and prevent the springs or contacts from touching the fork tube and causing a short-out.
- the shorter mount is at the bottom of the fork (wheel end)
- the lengths are sized so there is about 1" of pre-compression (combined) on the springs when everything is put together.
Step 9: Mount Batteries in the Fork
after everything is in, you can mount the headset back together.
Step 10: Attach the Electronics
we've got an 18V pack in each of the tubes, connect in series to make 36V. make sure you have a fuse in there!
charging: we lost the Zappy charger so i'm not sure if it will work on the NiMH setup. probably it will do a slow trickle-charge, which is the safest thing anyway. you could build or buy a fast-charger but it will probably be a lot of work or pricey. i ended up making my own simple trickle charger that does 1/2 amp, so it takes a day to charge but it is safe and easy, no danger of overheating.
Step 11: Mount Wheel
Step 12: Go Cruisin!
now just apply flaming paint job! that will stop the rusting.
mods: add a couple more D-cells to 'overclock' the motor, and a banana seat and rear-wheel pegs for passengers.