Dual geared hub motor Big Dummy... the Green Machine

[cycle9]

[youtube]pqEGkmGWMzo[/youtube]

This Big Dummy setup was designed for a guy who lives in the mountains of
Virginia, and due to physical limitations, cannot always pedal. So it needed to provide
sufficient power to haul cargo up the (steep) hills when not being pedaled. He will be
pulling a trailer as well.

He didn't want a Stokemonkey for personal reasons, so we came up with this as an
alternative, using dual hub motors.

Details:
Front eZee hub motor
Rear BMC V1 hub motor in hand spoked wheel
Dual Crystalyte 20A 36-72V controllers
48V 20AH LifeBatt
Custom charge control circuit for over-voltage limiting
Custom throttle circuit, single throttle controls both motors
Under-voltage protection, with throttle reduction (not outright cutoff)
Paul Thumbies (I love these!)
Fat Max box mounted on Snap Deck for battery and controller
Total of about 2100 watts of power
Combined hub motor weight < 15 lbs
Combined expense: a lot (but it will be less the next time we do it)
Fun factor: major, it accelerates almost like a sports car

I wouldn't regularly ride a bike like this, because I'd get no exercise. But it
sure is fun to ride once in a while I especially liked taking it out "cruising"
one Sat night after working late on it, and zooming around cars containing surprised teens.
(He asked us to ride it around before he picks it up, to ensure adequate
testing. I don't mind!).

Since it has so much power, he's going to take it down to his DMV to register it
as a "motor vehicle." That should be interesting.

Morgan

 

[Almasi]

Torque look really good with 2 geared hub motor and only 40 Amp/48 volt power, look like it has lot more torque then a single Crystalyte 5303 at 48 volt !

 

[cycle9]

Yes, it is extremely torquey.
Just imagine if we replaced those motors with BMC V2-T motors running at 72 volts/30A! Uh oh, now I might
just have to try it sometime..... maybe it would burn rubber.

Morgan

 

[Vim]

Darn, he's picked it up already? :| I was hoping to see it in action when I come to pick up the hub wheel you're building for me (black rear AmpedBikes 9Cont). You did show it to me before it was finished and it's a very impressive build, and I love those Big Dummy bikes. You have a nice shop and it was great meeting you and Kristen, and see all the projects you have going on.

Nice video too, Morgan!

Robert

 

[cycle9]

Hi Robert,
Thanks! He hasn't yet picked up the bike, but maybe he will this weekend (BTW, Saturday is the grand opening celebration for our new Carrboro, NC store). If it is still around when you come in, we'd be happy to show you. I love the Big Dummy - my own ride is just about my favorite bike of all time, and I've had some nifty bikes.

Sorry for the hold up on your 9Cont rebuild... those spokes are an odd size that took a while to track down.

It was great meeting you, thanks for visiting us!

Morgan

 

[liveforphysics]

Great project!