electric bicycle - Fuel Economy, Hypermiling, EcoModding News and Forum

sweatbrah · 10-16-2008, 04:05 AM

ok so i am wondering what it takes to build an electric bike.... i need it too go about 20 miles thats more then enough for my commute to school... the other factor is that there are hills but nothing steep just long soft sloping hills.. i also i know probably not legal but just get rid of the pedals and have the electric engine control the whole bike... i guess i good top speed would be 20 or 25 maybe more cause there are some mountain trails in the hills where i live... well just wondering what kind of set up i can do...

ATaylorRacing · 10-16-2008, 04:55 PM

A few months ago I found an electric bike kit in Kansas City Mo or KS. With their top of the line set up you could go 40! I can't remember the name of the place or the price. They used a hub motor.

Blister · 10-16-2008, 05:27 PM

You looking to make it or buy it? The average prices on the internet seem to be between $300 and $400. Some can go 50 miles on a charge. If you used it every day, it could easily pay for itself pretty quickly.

sweatbrah · 10-16-2008, 05:45 PM

wow 4O would be intense but fun haha.... Well would it be cheaper to build a bike or get a kit or an already made bike... I am looking to do this on a mountain bike

Blister · 10-16-2008, 05:54 PM

Quote:

Originally Posted by sweatbrah

wow 4O would be intense but fun haha.... Well would it be cheaper to build a bike or get a kit or an already made bike... I am looking to do this on a mountain bike

I only did a search for kits. If you already have a bike you like, a kit would be the way to go. This page has a link to a video of one (they're selling them) with a hub motor like ATR mentioned.

E-BikeKit: Media E-Bike Conversion Kit

The whole thing is basically hooking up wires, some light assembly and replacing the front tire. ->IF<- it were me, I would go with something like that provided I was happy with my existing bike.

I don't know how a hub motor works so I couldn't build one. The one I would build would probably chew the rubber off the tires.

bennelson · 10-16-2008, 07:34 PM

Your exact requirements would be met by a 36V system using 3 18AH sealed lead acid batteries.

I know because the specs you listed were exactly what I had with my kit using said voltage and batteries.

If I were to do an electric bike again, I would just build it myself with a motor right behind the seat and a chain going down attaching to the left side of the rear sprocket.

I saw a really nice electric bike a few weeks ago.

PHOTO HERE

If you are really interested in how that one works, I could pester the builder with any questions for you.

roflwaffle · 10-16-2008, 07:46 PM

Get one of those 36-48V scooter motors/controllers offa eh4y, a flip-flop hub, a rear rack, some mounting hardware, and three or four batteries from a junk yard. It'll weight a ton but it shouldn't be more than a couple hundred bucks and it'll go ~30-40 miles at 10mph w/ no pedaling. Just make sure it's geared right, both for the e-motor and you.

bennelson · 10-16-2008, 08:11 PM

Yep, except I would say to get some smaller batteries.

I was using 18AH batteries and it was just almost exactly as heavy as I would want a bicycle.

Maybe salvaged UPC batteries would be a good choice.

roflwaffle · 10-16-2008, 10:39 PM

The only thing I don't like about using a 36V 18ah setup would be range. W/ only about 650Wh available, they could only push the cyclist ~12 miles at 10mph. 36V of small starting batteries should yield about ~35+ miles at 10mph, while adding ~60lbs more than the smaller setup. If there are smaller batteries to be found for cheap I think they would work just as well w/ a couple parallel strings but at a slight weight penalty per kWh (more packaging), but AFAIK the only cheap batteries I can get consistently are used starting batteries for ~$10-25/kWh.

bennelson · 10-16-2008, 11:31 PM

The best part about a bicycle is that it's a hybrid!

By keeping (and using) the pedals, you would be suprised how much you can increase the range.

I would use nothing but pedal power for about 3 turns, then just crank the juice. Then I would pedal along with the motor going. Mostly I did that because my legs would have just been bored, but the motor was doing most of the work.

I got 20 miles to a charge with 3 18AH batteries that way. And that was with MUCH higher speeds and distances than the lazy and out of shape me would do otherwise.

Also, check with your local laws.

I know that in my area, to still be considered a bicycle, the vehicle must still have pedals (use 'em or not, they just have to be there) and a top powered speed of 20 mph.

That 40 MPH electric bike would be considered a motorcycle by law in many places. Drive that without a cycle license, and you could have trouble!