Rest of You: Bike Forces

IMG_0726(note: I’m awaiting the HR sensor, this is mostly outward forces)

I’m logging the acceleration forces at the handlebars of my bicycle while riding through New York City. The body has roughly three contact points with a bicycle, the hands at the handlebars, the “seat” at the saddle, and the feet at the pedals. The downward force of the rider’s weight and pedaling force and the upward forces of the bicycle rolling over uneven ground are distributed over these three points. I was interested to see just what kind of forces are “pushing back” that I may not be aware of, myself lost in the act of simply keeping the bicycle upright and safely navigating through traffic.

handlebar_vibrationTo contextualize the raw accelerometer data I also tracking GPS location and eventually geocoding the raw data in software. The bicycle sensors are being transmitted via Bluetooth to a mobile phone and the data is logged with a custom written (but now open-source!) python script. Below is the first draft of the visualization.

I intend to add more sensors to record internal forces to see if there is a physiological response (HR, GSR, breathing, pressure on contact points) to external factors such as speed, traffic / road / weather conditions, time-of-day etc.

Video demonstration of the initial visualization.






5 responses to “Rest of You: Bike Forces”

  1. Justin Avatar

    Very cool. Especially since this is the first time I understand what you were doing !

  2. Grega Avatar

    Hey Robert!

    Nice project you got there, I was thinking of something similar (just GPS and acc. meter) for my first semester project.

    Is there a way, to be able to use this python script on iPhone? I have iphone 3g, but no s60 phone arround, so i’m looking for a implementation of that if possible.

    Grega Podobnik

  3. Robert Avatar

    I’m not aware of a way to run python scripts (or any interpreted language) on the iPhone. Also, Bluetooth on the iPhone has very limited functionality, so I don’t think that writing an Obj-C version of the data logger would make a difference. I have an older Nokia 6682 which I keep around just for things like this.

  4. Robert J Carlsen Avatar

    I would love to see a satellite view map under the track so you can see the terrain you are passing over at each point of the track.

  5. Michael Avatar


    Try or We’ve used standard GPS data collected in cars in Google Earth to visualize driving routes.

    I’ve been planning my own bicycle data logger in my head for some time now, and I think the accelerometer is key to determining instantaneous power output, particularly on slopes, as it acts as an inclinometer. I was interested to see it used for evaluating riding forces. You may be interested in the International Roughness Index. I think NHTSA or US DOT has some massive databases on roadway roughness.

    I’d love to take the Garmin Edge 305 and add accelerometer data to it. The 305 already has GPS, crank and wheel speeds (can determine the gear you selected), but I doubt the GPS altitude information can indicate the slope accurately enough to determine the force.

    Michael Woon

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