A Pedal-Pushing Drive Build


100 µW
Aug 24, 2009
Hello All,
This is my first post, having discovered this forum about halfway through my project. The craftsmanship and ingenuity of the folks here is stunning. After watching the many creative and well-executed solutions posted here I hesitated to share my own "non-hub drive" with such a crowd of master builders. But, here goes...

The build resulted from a challenge by my son, a former pro bicycle racer, and is purely for fun. Could I build an electric tandem based on actually pumping the pedals? Would it climb the steep hills where we live? The result of the challenge is Joules, who sits on the stoker seat and does all of the pedaling. The fun part was coming up with a drive linkage that would use human-proportional legs to pedal in a circle matching the pedal cranks. The linkage delivers force tangent to the crank circle through the whole pedal revolution. The kinematics of the result are interesting to watch. (Hope that as a newbie I can get a video to work...)

you tube post: http://www.youtube.com/watch?v=HcW-VzpgcE8

I'd appreciate any comments/questions.

Regards, guys,

:shock: OMG, a true work of art!!! :mrgreen: much respect
Wow! :D
Congratulations, watching this marvel is really something that makes an engineers heart beat faster! :shock: :roll: :lol:

Please let us know more about the story behind this mechanical wonder. Tell us more about the motivation, project planning, hours required, machining, and not least the reaction from family and friends.
Dude, Carl, where have you been? That automaton is a cyclist's best friend. It would be even cooler if he sensed how much the driver was helping and shouted encouragement ( or insults) with your voice!!

Please, more details like weight, materials, and what kind of tools did you use.

Welcome to The Sphere, Non Hub Motor Drive? YES!!!
That is awesome.... :lol:

It gives me the same chills this...


I was up late one night just blown away by this stuff.

Thanks for posting Carl...! were you inspired by Theo Jansen?
Joules is absolutely fantastic! High quality work, well done Carl and welcome to ES! :D

More pics/info?

Paul :D

Brilliant! If that is you in the video, you are an inspiration to all of us over 40 (well maybe a little older in my case). I bet your son is awestruck and very proud!

WOW!!!! that brought a smile to my dial.
:mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:

Beatiful work indeed.

This is definately the sort of thing that will get e-biking noticed by the general public!!!
Beautiful work ! How much does Joules weigh? You might consider looking for a sponsor (Red Bull makes it feel like you've got an extra pair of legs pedalling", etc)

The news is always looking for "fill". You might start out with a local newspaper, and that would make it easy to get noticed by a local TV news program. I have no doubt this would get picked up by the national TV news for a 30-second blurb.

WOW, Kudos, very impressive. What's next?
Hi Guys,
Thanks for all of the great replies to Joules so far. To answer some of your questions:

--- The build was motivated by a couple of things. One, I wanted to see if I could regain a few shop skills. The last time I had touched a mill was during Nixon's first term. Second, I was frustrated because I meet very few kids who get excited by actually building something. I wanted to show local kids that having ideas and building them is FUN! We need lots of kids to believe that, I think.

--- Joules plus the Trek tandem plus the battery/electronics box weigh about 200 pounds. Had I found you guys sooner, I could have saved quite a bit of that with Matt's (Recumpence's) drive. That concept is genius!

--- Most of Joules' body is 6061 aluminum, with load-bearing bushings for bearings and such made from 316 stainless. Bearings, shafts, urethane, screws, sprockets, chain, etc. mostly came from McMaster-Carr (a treasure for builders), with the Gates timing pulleys and belts from Grainger.

--- All of Joules was built in the basement over the course of about 4 months, plus lots of semi-idle time on other things. I used a Grizzly mill-drill and an old Jet lathe. Body shapes in 0.25 in. aluminum used a jigsaw, router plus templates (scary!) and a lot of filing.

--- Here are a couple more photos, of the electronics box innards and some of the speed-reducer. Joules uses two Ping 48V, 15AH packs with an Alltrax controller. Given the available torque, the current limiter on the controller is set to 60A to keep the bike (and me) intact.




im truly lost for words at the craftmanship and engineering shown with "joules".simply amazing.
Welcome to ES.

Hi Carl,

Great job!

Greyhair said:
Hi Guys,
--- The build was motivated by a couple of things. One, I wanted to see if I could regain a few shop skills. The last time I had touched a mill was during Nixon's first term.



Regain a few shop skills? What were you building before? Lunar Rovers for NASA? :D
Art comes in many forms doesnt it.

Boy you got time and cash to spend.

Looking at your work you have plenty of skills to rely upon here.

Edit. Pictures dont always express a few words in a post. :oops:
Do you controll the mech rider with a throttle or is it off on type of setup?
Per a question: I control Joules using a right side twist-grip throttle, plus a toggle switch mounted near the left hand grip so that a flick of the wrist cuts off the controller. There's also a main battery switch easily reachable down on the battery case.

I've noticed that the twist-grip method can be a little tricky to control well during acceleration surges or hard braking. Has anyone settled on a throttle control that works well but that doesn't cause sudden inrushes of breath at tricky moments?

I can see a rowing crew, with one human. A little hidden prop would put you in contention.