sweet stuff. i’ve been thinking about this for some time now.
obligatory xkcd:
http://xkcd.com/139/
http://xkcd.com/409/

Posted at 11:30 pm on Apr 15th, 2008 by mattm

Any relation between this and http://xkcd.com/409/ ?

Posted at 3:15 am on Apr 16th, 2008 by ljn1981

I’ve been interested in this idea for a while. I skateboard, and also like cheap transportation.

Problem is the energy ratio is off balance. Most electric motors within practical size are maybe 800W at most. Which is usually around 1 1/2 Horsepower if I remember correctly. I weigh 190Lbs.

Using distributed energy in the form of a pulley system and clutch would work, but the machine work would cost a fortune. It might go 8MPH with me on it, and drain the batter in no time. I’d use some solar.

Posted at 8:46 am on Apr 16th, 2008 by TJhooker

the forkencycle is pretty sweet!

Posted at 8:54 am on Apr 16th, 2008 by dirk

Wow that’s pretty good ! I’m pretty surprised he gets 45 mins of runtime from it ! It would be cool if he could turn the wheels into a mini generator so that when going downhill it charges the batteries.

I don’t think adding solar panels would be very helpful though. (They’re VERY expensive, and generally not so small) Adding a little plug to the skateboard that would then connect to a solar station to recharge while not in use would be for feasible.

I’ve done a little solar project :
http://www.techienation.com/?p=21

Posted at 9:07 am on Apr 16th, 2008 by DigitalMind

That forencycle is cool. I’ve been rolling the idea of a one cylinder turbo-biodiesel motorcycle over in my head for a while, I just don’t have a workshop or the budget to build it in. You can get decent little diesel engines from northern and other places, I think they use them in generators and pumps and stuff. Or maybe I should modify a regular gas scooter to run on e85 or something.

Posted at 12:35 pm on Apr 16th, 2008 by Mike

did he use carpet as bearing?
ball bearing is not expensive and easy to use.
http://philipdoering.googlepages.com/goliath

Posted at 12:45 pm on Apr 16th, 2008 by Philip

to tjhooker…

800W is closer to 1 hp (748ish watts/hp), and it’s plenty to move a person. I just got back from the shell eco-marathon in California, and we had a solar car that kicked some major ass at the competition. their weird EV conversion factor put us at 2861 mpg, but the actual useful numbers was the fact that we pushed a 158 lb car with a 120 lb driver at around 15-16 mph, using around 170 watts. This was also with 20 mph crosswinds and headwinds, and gusting to around 50 mph. It was powered off of 3 small lead acid batteries (couldn’t get the li-ion pack working right), so basically a 36v system with 7.2 amp hours.

Now that the long-winded explanation is over… As long as you have good starting torque, the power consumption isn’t a problem really. regen would be easily doable, and a quick charger could probably get it charged in under an hour of plug-in time. We had about 3 m^2 of solar cells (only 20% efficient, though), and it was just getting enough to get us into the positive power range. So for the solar case, adding a few cells won’t run anything save for some control circuitry. a charging station is a much better idea.

Posted at 1:37 pm on Apr 16th, 2008 by cole

Oh, and to add on to that, go to http://www.purduesolar.org for some pics of the car. Just to give you a sense of scale and whatnot of the array size to amount of power given out by it. Keep in mind that the back left array section had a broken tab, and didn’t give out any power, which sucked, but it still worked.

Posted at 1:38 pm on Apr 16th, 2008 by cole

Kinda funny, I was building something like this using almost the exact same parts/design. I got an old “broken” e-scooter for free and wanted to use its parts to motorize some kind of skateboard.

Posted at 11:15 pm on Apr 16th, 2008 by Jack

philip–

The carpet isn’t serving as a bearing, it’s just a shim to keep a snug fit against the non-rotating shaft. There are ball bearings built into the wheel hubs.

Posted at 10:56 am on Apr 17th, 2008 by Perry Jones

I’ve been planning on of these for a while, using RC components instead of scooters. More expensive, but lighter-weight and far more powerful. An AXI 5330/18 motor is approximately half the size of the one used here, and max output is in the range of 2800 watts. It costs $200 though, instead of $30…

Size of motor (it’s the big one):
http://www.hobby-lobby.com/images/axisr.jpg

Posted at 12:10 pm on Apr 17th, 2008 by firebat45

@firebat45

2800 watts would be a lot of juice. I never thought about using RC motors for something like this.

Posted at 6:23 am on Jun 20th, 2008 by actionisle