Category Archives: workshop

Arduino design Interactivity workshop

Interactive Design Update: A Sequencer in Max/MSP

Steve redesigned the interactive component of the Movable Party machine. This time, Steve made the the Max interface function like a sequencer. The rider can use the hub motor sensor (RPM) to advance through a sequence of preset patterns while varying the BPM and and pitch. Enjoy.

generator workshop

A Sneak Preview of Our System

We connected all three hub motor bikes that we’ve built and pedal-tested the setup to power a PA system. Yes, indeed, our efforts have prevailed. We supplied enough electricity to power a PA system (Gigrac 600). Hurray!!!

We’re ready for our campus launch on Founder’s Day on April 20th, and our community launch at CicLAvia on Sunday April 21st. Event details.

bike mechanics design generator workshop

Video from Workshop #1: Hub Motor + Bike Generator

In this workshop, Josef Taylor, structural engineer of Buro Happold, LLC, took us through the steps of using a hub motor on a bicycle to generate power, while explaining the laws of physics related to electricity. We compared the resultant voltage generated while using various levels of resistance in the circuit.

Arduino design Interactivity Music Sensors workshop

Video from Workshop #2: Arduino and Sensor Fun!

Movable Party 1.0 // Workshop 2: Sensors, Arduino, & Interactive Media

#MovableParty Workshop 2 was about the design of an interactive system. We placed sensors of various types on the handlebars of one of the bikes with a hub motor. Our workshop leader Steven Kemper mapped the pressure sensor data through Max MSP to demonstrate different effects (parameters of low-pass filter) on a song. The Hall Effect sensor was used to set the tempo of the audio playback. Jack Moreau is our DJ on the handlebars for this round! This workshop took place at Occidental College’s Brown LearnLab. Participants included students from Occidental College and members of The Bike Oven.

bike mechanics generator workshop

Workshop #3: Bike + Hub Motor Assembly

Hub Motor on Bike at the Knowhow Shop
Hub Motor on Bike at the Knowhow Shop

Linda and Joe will be running a workshop on bike and hub motor assembly tomorrow, on Saturday March 23 in the Bike Cage on the campus of Occidental College. Come on by if you are curious about bike mechanics, and want to assist with the mounting of a hub motor and all the necessary electrical components on a bicycle. We will be working with donated bike frames and components from the Bike Oven and Flying Pigeon. Thanks for their generous offerings!

Our goal is to build a second bike for Sunday’s Arduino workshop. Ready to get your hands dirty!

Place: Bike Cage at Oxy [southwest corner of the Rangeview parking garage, come through the gate and turn right]

Time: 1-4 or 5pm, Saturday March 23

Arduino Interactivity Sensors workshop

Workshop #2: Sensors, Arduino, and Interactive Media

Movable Party Workshop #2

Our workshop #2 is happening on Sunday March 24, 2013. Get psyched!

In this workshop, we will introduce the design of the project’s interactive media/music system. In particular, we will explore interactivity and the Arduino microcontroller platform by attaching sensors to the bikes and using the resulting data to control musical output. Specifically, we will be using Hall effect sensors to measure the speed of the rear wheel of the bike, as well as pressure and flex sensors to capture movements of the riders. We will also discuss issues of design and physical computing—using sensors to translate (transduce) action in the physical world into computer data.

Time: Sunday March 24, 2013, 2:30pm
Place: Brown LearnLab, library
The Bike Share will buy some pizzas for us.

The workshop should last 2.5 hours. If you want to get a head start on the workshop, read these two posts by Steve:

This is the beginning of the interactive music design. If you would like to learn about robotics and interactive media design, this is it for you!

design generator workshop

Generator Development

We’ve just received many of the parts for the generator, and will test them out this week! Suddenly all of the planning and fund-raising and cogitating is going to be attached to a couple of bikes with power cables coming out of them. This is a big step, so I suppose it’s time to update everybody on how this thing is going to work.

Hub Motors

We bought our motors from in Vancouver BC. There are more local options, but these come highly recommended, and there is a wealth of information and support at their website. The motors are “brushless DC motors,” which is a bit of a misnomer, as the motor itself runs on (or outputs) three phase AC. In a motor application, that AC comes from a motor controller which converts 12V DC into a variable frequency, variable voltage power signal according to the desired speed and power. Since we’re using the motors backward, taking power out instead of putting it in, we’ll need to make sense of that 3 phase AC.

Nine Continent Rear Hub from
Nine Continent Rear Hub from

The motors come in three different windings, from 6 turns to 8 turns. This is equivalent to using gears of different sizes on your bike; if you supply a given voltage, the 6 turn motor turns faster than the 8 turn motor, but with less torque. What this means to us is that the 8 turn motor will supply our target of 14V at a lower speed, meaning that we can use the low gears we’ll need for hauling cargo. However, it might be too much, and we’ll have to use super low gears to keep our voltage low. We ordered a 7 and an 8 turn motor, and we’ll figure out which one we need once we have the bike in the trainer and a load attached.


A rectifier takes the alternating output of a motor and converts both the positive and negative peaks into positive current, effectively flipping all the troughs into peaks. It works by feeding the alternating current through an arrangement of diodes (which only allow current in one direction, like a check-valve). Ours are packaged in neat little boxes with spade terminals and a must be mounted on a heat sink; the diodes don’t put out a lot of heat, but it’s enough to damage them if they can’t dissipate it.


We’re using the element from a ceramic space heater as a load. This is basically a big resistor; current has to pass through a series of special ceramic blocks that are poor electrical conductors. These heat up, normally to heat the air blown through them. This element is unfortunately a bit too strong, with a resistance of 180 ohms, but since there two elements, we can connect them in parallel, cutting that resistance down to 90 ohms. If I’d been able to find a traditional coil element, we could clamp on anywhere along the coil to adjust the resistance.

For a more visible effect, we picked up three 100Watt light bulbs. These have a resistance of 144ohms apiece, but connected in parallel we’ll get 48 ohms, which is a pretty reasonable load to power.


One of the toys we received is the Watt’s Up meter. This little guy connects in line with our power, allowing us to see just how much power, in volts, amps, and watts (just so you don’t have to compute the product). This means we can finally get a good idea of what a person puts out on our system! This is really exciting.

Alright, see you at the workshop!

community generator partnership workshop

Workshop #1: Generator & Hub Motors

Bikes with Hub Motors

We’re excited to announce the first of our workshop series for Movable Party. In this workshop, we will be fitting the bikes with hub motors and testing their electrical output. We will talk more generally about the laws of physics related to electricity, and compare the results of two different hub motors.

Place: Bike Cage at Oxy [southwest corner of the Rangeview parking garage, come through the gate and turn right]

Time: 5:30pm, Friday March 8

The workshop will last no more than 90 minutes. We will have some pizzas! Please let me know via email [hsuw at oxy dot edu] if you’re coming, so I can make sure that there will be plenty of food for everyone.

We’re excited about moving our project forward. Come and prepare to get your hands dirty!