john2364

This topic does not really belong here but this forum seems to be the closest match for the topic. I am very interested converting a bicycle to electric power and am trying to decide the best motor. I want to be able to bring my bike upto 25mph comfortably with a max speed of 30-35mph. Based on my research in electric bikes, I should be able to accomplish this with 1500 watts of power. I am considering using an RC motor however, I am concerned that it will not work for some reason that I do not yet understand.


Here is where I am confused, Motors for full sized vehicles or industrial applications seem to be far larger then the equivilent RC motors. For example, a ebike/industrial motor that will put out 1000 watts on 24 volts may have an amp draw of around 30-50 or maybe a bit higher. The RC motor putting out this wattage will have a similar amp draw. They will both put out 1 to 1.4 HP. Nevertheless, the ebike/industrial motor is probably 3-4 times the size of the same RC motor. I just do not understand why there is such a large size discrepancy. I am tempted to use an RC motor because it is far less expensive however, an RC motor that will put out 1500 watts on 24v just does not look large enough to propell me to 20-35mph on a bicycle. I assume that the RC motors have much higher RPMs but that is easily solved through gearing down. Do any of you have an explanation for the discrepency in size or a recomendation on what motor to use?

FoamyVictim

Are you looking for a Brushless motor or a simple DC motor?

Here's a brushless motor that might do the trick:

http://www.hobbycity.com/hobbycity/s...28eq:_70-55%29

genitor

The e-bike motors you are looking at are most likely brushed motors. While you most likely have been looking at brushless rc motors.
Brushless motors are far more efficient than brushed motors and this accounts for the 'size discrepancy' you mentioned.

Check out these two threads on hobbycity's forum:

http://hobbycity.com/hobbyking/forum...s.asp?TID=6740

http://hobbycity.com/hobbyking/forum...ts.asp?TID=289

These people did the same thing you are trying to do.

solarbikeau

Hi, I've done quite a bit of research on electric bikes and specialise
in conversion kits. I recently went to China to visit some electric
bike factories and shows. If you're interested in watching a short
documentary on the electric bike scene in China please visit my SOLAR
BIKE website and watch one of the videos I made.
http://solarbike.com.au/videos.php Otherwise search youtube for
"Electric bicycles in China documentary" and it'll be the first hit
http://www.youtube.com/watch?v=_KA47vf6f64 . Happy Cycling. Matthew
from SOLAR BIKE

solarbikeau

The 2011 GIANT CROSS CITY 4 is a sporty, fast and comfortable bicycle that is ideal for electrical conversion. The quality running gear, good price and chromoly steel forks make it an excellent choice for a very fast transportation machine. This model pictured here I converted using a 500W motor and a 36V 10Ah lithium ion battery (LiFePO4) that comes in a custom designed lockable double layered rear rack. It offers a speed of about 35km/h and a range of approximately 30km with light pedalling. The bike retails in many shops for around $600. The kit is $890 through Solar Bike, www.solarbike.com.au . The triple walled deep V rim that comes with the motor kit are a good improvement. Installation took about 1 hour. Matt

500W Electric Giant Cross City 2011 model

sloppyG

just get a good road bike, it's not that hard to ride 20mph without a motor if you're in decent shape

don't be so lazy

SyCo_VeNoM

only 20?
Saw a video a long time ago with some guy with a Schwinn converted to electric that could pull 50mph

Wow a 2wd bicycle
http://www.youtube.com/watch?v=xP6fA...eature=related

electricrc68

i wonder if that turnigy brushless motor will fit in my electric scooter....hmmmm.....

collector1231

My Feedback: (1)

Why you don't buy a KC Cruiser bike and add a elec. motor? You'd save lots of work. http://kcsbikes.com/

hands without shadows

The E-bike motors are big because they are usually direct drive and they are built much cheaper than our brushless motors. A big outrunner is the way to go. Guys in the heli forum probably have better recommendations based on kW*quality/price then you will find in car forums.

For driving the motor you may get away with a boat/heli/plane ESC, as you don't need reverse and possibly don't need (electric) brakes.

For speed control you could buy a servo tester such as [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXVK79&P=ML]this one.[/link] It plugs into the ESC and moving the dial on the tester is like moving the throttle on your transmitter. The knob moves a simple potentiometer. If you were to measure the potentiometer's value, you could shop for a twist throttle with the same resistance value on Ebay and wire it in.

If your handy with a soldering iron and would like to try building a simple circuit, google "[link=http://www.google.com/search?client=opera&rls=en&q=build+servo+tester+555&sourceid=opera&ie=utf-8&oe=utf-8&channel=suggest]build servo tester 555[/link]build servo tester 555"

janlim

There are a few different ways to solar charge an electric bicycle but