Electric Bikes - Conversion to electric (no kit)

Conversion to electric (no kit)

I've got a multispeed bike that I want to convert to a pedal/electric bike. I'm not going to use a hub motor because I want this bike to assist me for climbing hills and that means TORQUE.

I'm thinking of using a brushless motor linked by chain to one of the gears on the back wheel. I'll sacrifice some gears but I'll live with it.
As a motor selection I was looking at this:

BM 3500KV Tuborix 438W

Specification:
rpm/v (kv) : 3500
Suggested Battery : 11.1v Lipo Battery
Load Current (A) : 39.5A
Load Speed (rpm) : 21700
No Load Current : 3.7A
No Load Speed (rpm) : 38700
Recommended ESC : Turborix Advance 40A ESC
Suggested Propellers : APC 5.5 X 4.5"
Weight : ~60g

or this:


Brushless EMGC AX-2212H 3350KV
Rotational Speed 3350 RPM/V
Continuous Current 20A
Max. Current 25A
Input Voltage 8 - 12V
Max. Efficiency 96%
No Load Current 0.7A
Internal Resistance 106mO
Motor Dimensions 28mm x 30.3mm
Shaft Dimensions 2.25 x 14.2mm
Input Battery Types NiCd/ Nimh/ Li-po Battery
Recommend Model Helicopter / Airplane


To pedal when the motor isn't running I'd like to put a freewheel mechanism on the output shaft of the motor. Can I find one of these to buy separately from a new wheel?

For batteries I have a box of 2000mA LiPo cells left over from another project. These should do nicely if I tie more together.

Any advice? Are the motors I've selected good for an e-bike?

You might want to read this thread on using RC motors for e-bike builds that's in another forum as well as post some questions there (many more e-bike builders there, I think). http://endless-sphere.com/forums/viewtopic.php?f=28&t=4625
There are many other interesting threads that I suspect you'll want to read in the e-bike non-hub motors section of that forum.

You'll definitely get more torque with that type of setup. I bought the Currie kit, which is similar to the design you've proposed, because it has great torque. (Surprisingly, it's also one of the most affordable e-bike kit out on the market right now.)

Good luck.

I would buy a Currie kit because I quite like them but I'm in Romania and I can't find it around here. Shipping that big box of the currie kit would take a lot of money I reckon.

I don't know if Currie has any distributors in the EU. I know the izip and/or ezip have been sold there. The problem may be the EU restrictions--I believe e-bike motors sold in the EU can only be 200W or 250W; the Currie kit and many of the Currie models have a 450W motor. If there are EU distributors, shipping might be higher if from an EU country other than your own, but perhaps customs duties wouldn't be an issue.

You definitely would be able to craft your own e-bike from an RC motor. Check out the link in my other post. I think you would be able to have any questions you might have answered by the e-bike builders that frequent that forum. It's got members from all over the world. They do some pretty fantastic work, too. Good luck.

Gilius

There are some good resources in Europe:

http://www.bike-elektro-antrieb.ch/home.htm in Switzerland make motor mount kits including freewheel pedals.

http://www.pedelecs.co.uk/forum/electric-bicycles/ have a lot of info for products your side of the sea.

A 48v 1000w gearless hub motor of quality will provide more pull up hills then you will ever need.