Excite BikeRear ViewDrive TrainDrive Train 2Battery PackFront viewSide View
OwnerEddie Kloth
LocationBurbank, California United States map
Email email image
Vehicle2005 GIANT Boulder
A father-son summer project that turned out to be quite rewarding.
Well I saw that my dad was building an electric motorcycle using two E-teks and thought, "well thats kinda cool." I'm 15 and I'm not old enough to drive yet so I decided to convert my mountain bike into an EV. California law is pretty lenient on electric bikes.

It states that:
1) You don't need a license
2) The motor must be no greater than 1000 watts
3)It can go no greater than 20mph
4)The rider must be 16 or older.
Well my bike and I don't fit any of those standards but how are they gonna know heh heh! Funny thing is that we finished my mountain bike before my dad finished his motorcycle (he is still deciding on his final designs and whether or not he is going to use the Lithium DeWalts).
MotorUnite Motor MY1020 Permanent Magnet DC
MY1020 48 Volt, 1200 Watt, 3200 RPM, 32 Amp, permanent-magnet motor.
12 gauge power leads with standard 1/4" push-in connectors.
11 tooth sprocket for #25 chain.

Motor Dimensions: 4-1/4" W x 6" L not including shaft. 4-1/4" W x 7" L including shaft.
ControllerYi Yun YK42-4
Rated Voltage
48 Volts
Rated Current
40 - 100 +/- 1.0 Amps
Rated Motor
Up to 1200 Watts
Conversion Efficency
Under Voltage Protection
42 +/- 0.5 Volts
Speed Control
Hall Effect Throttle
(1 - 4 Volts)
17 cm x 9.0 cm x 4.6 cm
Batteries4 Universal Batteries 12220, 12.00 Volt, Lead-Acid, AGM
22ah each
14 lbs each
7.1" x3.0" x" 6.6"
System Voltage48 Volts
HeaterWell after running the bike up and down some merciless hills we found that the motor was beginning to overheat a little too much to the point where I had to stop to cool down before my batteries ran out of range. So we went to APEX, a crazy electronics warehouse, and found a $5.00 12v DC fan to slap on the motor. Fan only draws 0.5 amps. Now the motor runs nice and cool even in the hot California sun. Just goes to show that fans can make a SIGNIFICANT difference without using too many amps.
DC/DC Converter
I'm gonna get one cuz the fan can only run on one battery at the moment (12v 0.5 amp fan) and it kind of unbalances the pack. Also when I put some lights on I'll a DC/DC converter. No accessory batteries here.
InstrumentationThrottle Cable (Hall Effect Twist)

cheap BELL brand bike speedometer (wired).
We at first got the wireless version but ended up returning it cuz it sucked and acted too erratic. The electric signal from the bike might have interfered with the wireless speedo but maybe wireless speedometers are just crap.
Top Speed40 MPH (64 KPH)
40 mph maybe more (too dangerous on mountain bike)
Acceleration is phenomenal on flat land.
UP hills I can get it up to 27 mph in less than 30 seconds.
Acceleration0-20 mph in less than 10 seconds
Range15 Miles (24 Kilometers)
(Without pedaling!)
15 miles. Where I live there are terrible, almost San Francisco-like hills so i couldn't ask for any more. Would probably go more than 25 miles on level ground.

(With Pedaling)
Wowzers would go exceptionally far
Seating Capacity1 adult
Curb Weight91 Pounds (41 Kilograms)
Its a beast. We had some problems with stock bike kickstands bending and snapping. Its still pretty freakin fast even with me a 190 pound rider on it.
TiresStock tires came with the bike
Conversion TimeProbably 20+ hours of misc. weekend work (I don't really know) because keeping the pedals led to a much more difficult design of the drive train.
Conversion CostOriginal Giant: Boulder Bike $200.00
Motor $90.00
Controller $45.00
#25Chain 11 tooth sprocket(for motor)$5.00
#25 Chain $6.00
#25 Chain 80 tooth sprocket(on hub) 10.00
Throttle Cable (Hall Effect Twist) $7.00
4 12v 22ah Universal batteries $136.00
BELL Speedometer $16.00
12v DC fan $5.00
Charger- Use my dad's
Mounting Hardware $20.00
Misc. Hardware- Around the house

Conversion Cost= $314.00

Total Cost (with original bike)= $514.00

I got most of the conversion components from TNC Scooters. I like that store.
Additional FeaturesPEDALING. We made a great effort to avoid scrapping the use of pedals by building a drive train similar to a CURRIE DRIVE. Pedals can be a very important feature especially if you happen to run low on batteries and still need to make it home. ALSO, STOP signs can be dangerous to your wattage cuz dead-stop startups are generally going to be where you draw most of your amps and lose most of your juice. By incorporating the pedals, I am able to lightly assist on startups and increase my range SIGNIFICANTLY.
I'm probably gonna end covering all of the batteries and ominous wiring with a canvas material cuz my mom says that I look like a unibomber when I ride the bike. I just hope that the cops don't think the same thing. All I can say is that if you live in a flat area, you are very LUCKY. Hills can really suck your amps and if you do end up building an EV, make sure that you compensate for the amount of hillage you have in your area. Luckily for me the "Bike to the Future" turned out to be quite a success even with the horrible hills.

ALSO, freewheeling of the motor is a big want but not necessarily a huge need. A CURRIE wheel with a dual hub could certainly help us implement freewheeling of the motor into our drive train. I just don't like the fact that the motor is turning even when I am not using it. It equals more heat (cuz the motor acts as a generator when the bike moves), and shorter life of the (who knows how good) Chinese brushes. Great thanks to my dad (Jeff Kloth) who really helped me with the project and who will soon be updating his own electric motorcycle onto the EV Album.

code by jerry