Has the winter weather got you down? Is the snow preventing you from training for the next Tour De France? Or are you afraid to ride outside with all those cellphone weilding drivers? Google bike is the answer for you! Now you can ride anywhere in the world in the climate controlled safety of your home.

Google bike is a virtual bike riding program. Using a few simple electronic components and some software hackery you too can ride in virtual style!

Here is the bike in action!

Step 1: Overview and Parts

Here's the gist. A sensor from a bike computer is used to detect the rotation of a bike tire. The output of this sensor and the turning angle (controlled by the thumb joystick) is read by an Arduino and relayed to a computer over a usb cable. The computer reads the number of rotations and angle of the joystick and uses these values to control a virtual bike within google earth!

Stuff you will need:

Indoor bike stand (or suitable stationary bike)

Bike cadence sensor (or reed switch and magnet)

Arduino

Small thumb joystick or harvest this from a PS2 controller

Computer with windows or osx (sorry linux :( blame google for not releasing the google earth browser plugin for linux)

Step 2: Bike Cadence Sensor

Google bike uses a cadence sensor from a bike computer to detect wheel rotations. Simple wired cadence sensors, like the ones used here, are typically reed switches embedded in plastic for protection. Attach the sensor to the back fork of the bike (this is important as the front tire doesn't rotate when the bike is in the stand) and install the supplied magnet on one of the spokes of the back wheel.

I had to splice the cable going from the sensor to the computer and install a 0.1" header to get access to the reed switch. The bike computer still works, but you may be able to avoid this depending on the type of bike computer or sensor that you buy. The cable contained two wires that act like a magnetically activated switch. When the sensor is near a magnet, the switch is closed.

Step 3: Thumb Joystick

Google bike uses a thumb joystick to control turning angle and reverse. I selected a simple thumb joystick and breakout board from sparkfun which looks identical to the kind found in ps2 controllers. The joystick contains two potentiometers and a push button switch. At rest, the pots (potentiometers) are at their middle positions and will output half (2.5V) of VCC (5V), move the joystick and the outputs of the pots will move between VCC and ground. Pressing on the joystick closes the push button switch and causes the SEL output to go to ground. When the joystick is not pressed, SEL outputs VCC.

I laser cut a small bracket so the joystick could be temporarily mounted onto the handlebars using a rubberband. I've attached the svg file for the mounting bracket so you can modify it to your specific needs.

joystick_fatter.svg
Download

Step 4: Arduino

Google bike uses an Arduino to relay sensor data to the computer.

First wire up all the sensors to the Arduino. See the attached schematic for a graphical representation of what I'm about to describe. You are free to change the wiring to your hearts content, but be warned! The cadence sensor must be attached to digital 2 or 3 as it is used to trigger an intterupt. Also, be sure to make any corresponding changes to the arduino sketch.

Attach one wire (it doesn't matter which one) from the cadence sensor cable to ground and attach the other to digital input 3.

Next wire up the joystick. Connect:

Arduino-5V to VCC on the breakout board

Arduino-GND to GND on the breakout board

Arduino-Digital-2 to SEL

Arduino-Analog-0 to VERT

Arduino-Analog-1 to HORZ

Upload the googleBike.pde sketch to the Arduino. Briefly, the sketch...

defines an interrupt routine with crappy debouncing that increments a rotation counter

configures serial communication

configures digital input 3 (the cadence sensor) as an interrupt

sets sensor pin directions and pull-up resistors

every 10 milliseconds, relays the joystick status and rotation count over the serial connection (which travels over the usb cable)

I've also attached a svg file that contains a mounting braket for the arduino that is similar to the one used for the joystick. Beware! The mount quickly broke because I didn't put in little cross-bars to reinforce the crappy glue joints. If you decide to cut this yourself I suggest either adding reinforcements or redesigning the mount.

Step 5: Python Server

Google bike uses a small python server to read incoming sensor data and serve up the google bike webpage. You will need to install python (version 2.something, the script is not 3.0 compatible as far as I know), and pyserial. Installing python and pyserial should be a relatively painless process with lots of useful information found via google. The only issue I ran into on windows was that I needed to install a 32-bit version of python as I could not find a 64-bit version of pyserial.

The attached server.zip contains the python code to run google bike. It includes:

arduino.py a very simple python module with an Arduino object that receives incoming sensor data

server.py the main python script that creates an Arduino object, a small web server, and launches the google bike page (index.html)

and other supporting files

Sadly, the serial port address is hardcoded on line 17 of server.py So... once you plug in the arduino be sure to correct this line before running server.py On a windows machine the line should look something like:

ard.configure_serial('COM6')

on mac it will look something like:

ard.configure_serial('/dev/tty.usbserial-A4001Lf4')

After correcting line 17, run server.py (either from the command line, or double click, etc...) and python should launch a web browser with the address:

http://localhost:8080/index.html

server.zip
Download

Step 6: Up and Riding!

Google bike should be up and running! Pedal to move forward, move the joystick to turn, and press the joystick to stop/reverse. Type an address into the search box to teleport to a new location (the default should be Googleplex, Mountain View, CA, USA) or click one of the presets.

There are lots of variables that can be modified within the bike.js file. Here are some fun examples:

change gravity (line 41) from 9.8 to 1.62 to feel like you're riding on the moon (helps for getting sweet air!)

increase acceleration (line 45) to reach ludicrous speed!

change the camera height and distance (lines 42 and 43) to get a zoomed out view for areas without 3d buildings

Be sure to fully refresh the page after making any of these changes so that your browser does not load the cached javascript file.

Step 7: Motivation

Aside from being a fun project, google bike was created as a christmas gift for my father. The past two years he and my brother (the star of the video) rode in the "Bike MS To Paradise and Back", a 100 mile bike ride to raise money for the National Multiple Sclerosis Society. The cold Pennsylvania winters don't have the best training weather for bike riding and my brothers and I wanted to get him a stationary bike stand so he could ride without braving the snow. He's also a big fan of google earth (who isn't!?) so I figured he would enjoy using indoor riding to explore new places.

A bit of research revealed a couple previous projects and I was encouraged to build a similar setup. One of the deciding factors was finding this wonderfully entertaining example of the google earth api that I was able to modify for use with the google bike. The bulk of the work was done the weekend before christmas and hopefully with the documentation here the project could be completed in a weekend or possibly a lazy saturday.

I attached various important files in this instructable that should allow you to create your own google bike. However, I also plan to maintain and update the following public repository:
https://github.com/braingram/googlebike

Good luck and happy riding!