1 - User Guide

This section helps you use your OpenBikeSensor (OBS). Think of it like the manual that came with the device, only we don’t need to print it. No matter whether you built your sensor yourself, or got a pre-built sensor from someone else, this guide describes how you can help collect important data with your fancy new device.

1.1 - Quick Start Guide

This guide assumes that you have a working OpenBikeSensor. If you don’t, start here!

In case you might get a OpenBikeSensor, you should do some first steps.

  1. Check, if your handlebar fits the OpenBikeSensor’s display/button holder. There are basically two different kinds of handlebars: thinner ones, with a 25,4mm diameter and the other ones, with a 31.8mm diameter. You might create some kind of adapter, if the device is designed for 31,8mm and you have a 25,4mm handlebar, but the other way around is not possible
  2. Measure the distance between the outer edge of the device and the end of your handlebar. Enter these values into the configuration options.
  3. Set your privacy zones. You could probably get the GPS location with any digital map app. Enter these values into the configuration options.
  4. Check the SD card, if it’s ok and - in best case - empty.
  5. Load the device’s battery.
  6. Turn on your device. Wait until the it has found your GPS location. This might take some time while we’re waiting for the sattelites to connect. The display will exit the status screen as soon as your location is known. While moving it might take up to 15mins, until the devices knows where you are – stand still for a faster process.
  7. Put your sensor on the bike and go for a ride. Please take care about traffic around you and don’t let the OpenBikeSensor distract you!
  8. Push the button every time you’re passed (no matter if it’s a car or truck or bus or motorbike). To get some idea how often close passes occur, it’s important to confirm every pass, not only the close ones.
  9. After your ride, switch off the device. Hold the button on the display while throwing the switch to ensure you don’t lose any data.

1.2 - Mounting the sensor to a bike

This page is not yet available in English. You might be able to read it in...

  • Deutsch: Montage des Sensors am Fahrrad

1.3 - Configuration

1.3.1 - Minimal configuration

At least three settings must be configured before you can use a new (or reset) OpenBikeSensor.

  • The left and right offsets as the largest width of the bike with rider (handlebar width, elbow, etc.)
  • API key
  • WLAN settings to upload your data

Enable configuration mode

To activate the configuration mode, press and hold the button to turn on the device.

There are two different modes of operation.

Access Point Mode

Without a configured WLAN in range, the OpenBikeSensor opens its own WLAN access point.

  • SSID is the MAC address of the device OpenBikeSensor-xxxxxxxx.
  • The default password is 12345678.
  • The configuration page can be accessed via in a web browser.

WiFi mode

If a previously configured WLAN is in range, the OpenBikeSensor will connect to it and show the IP address on its display. This is used to reach the configuration page in a device’s browser in the same WLAN.

Data can only be uploaded from a WLAN with Internet. This can also be triggered directly from the OpenBikeSensor by pressing and holding down the button.

Login to the configuration menu

Since version 0.6.x, an HTTPS connection is offered, and a PIN secures access to the web interface.

  • To open the configuration menu, click on go to https.

    • (Since version 0.6.x) When using HTTPS, a certificate warning is expected, which can be dismissed or silenced by importing the certificate into the browser. The certificate is presented for download in the dialog.
    • (Since version 0.7.x) Instead of go to https, the warning can be bypassed by selecting enable unencrypted access. This should only be used in secure wireless networks (example: own home network).
  • After selecting the configuration mode, the browser will ask for a username and password.

    • User: obs (Note: the username is not checked, and the only condition is that the string is not left blank).
    • Password: is shown in the display of the OBS.

Important settings in the configuration menu


OBS Main Menu

Offsets to the largest width are measured from the sensor. For a symmetrical bike with a 75cm handlebar width, the offset is (75-5)/2=35.

General menu: Setting the offsets

You must enter the “Personal API Key” found in your own account’s Setting menu in the portal. A list of available portals can be found in the Forum.

Important: Don’t forget to save.

General menu: Enter the API key


Main Menu

In the WiFi menu, enter and save the connection details of a WLAN with Internet.

Set SSID and password

This completes the minimal configuration with which tracks can be recorded and uploaded.

1.3.2 - Advanced

How to enter configuration mode

You can enter the configuration mode by pushing the button while turning on the device.

Access Point Mode

  • On first start of the configuration mode or if you are outside of the Range of your WiFi, the OpenBikeSensor will open a unique WiFi access point
  • The access point is named after the MAC adress “OpenBikeSensor-xxxxxxxxxxxx” with the initial password “12345678”
  • The configuration page can be found on “” on the AP

WiFi Mode

  • It might be neccessary to de-activate the mobile data on your mobile phone to access this page.
  • OBS can also connect to an existing WiFi, if credentials were entered in a previous configuration (see WiFi Settings)
  • Connected to an existing WiFi, the IP adress of the configuration page is shown on the device’s display.

Structure of the Configuration Menus



Define the offset between the end of your handle bar and the outer edge of the OpenBikeSensor. These values will automatically get substracted from the current measurement. Additionally you could “swap” the left and right measurement, in case you flip the device on your bike.


You could define, in which way your device will acknowledge a valid GPS fix and starts operation. Typically it will start regular operation when it has contact to 4 gps satellites.

Generic Display

  • flip the display, if you need to mount it upside down
  • invert the display bright / dark parts, which might help in bright sunlight.

Measurement Display

Here are several options, which values you might want to see on your display.

  • “simple mode” – display only of measurement to the left
  • Show left / right measurement
  • Show satellite – display of number of gps satellites recognized by the device (more satellites – more accurate positioning)
  • Show velocity – display of actual speed (quite rough because of slow measurement intervals)
  • Show confirmation stats – counts button press and confirmed detection of surpassing events
  • Show nerd details for distance sensors – display of raw data of sensors and number of measuring events within one second (helpful for troubleshooting)

Privacy Options

To keep some privacy, you could tell your device to stop recording near your home or any other privacy zone. This could be no recording at all or just no GPS-tracking any more, but still storing all confirmed passes.

Define your home location and diameter of the privacy zone in the corresponding menu.

Upload User Data

Setup for upload-server to collect track data

  • Choose a portal from the list in the forums
  • Visit the portal, create a user account, and open your profile settings page
  • Copy and paste the API URL and Personal API Key into the settings page of your OpenBikeSensor.


  • Enable Bluetooth – check if you want to connect your Openbiksesensor to a compatible Smartphone App s.a. SimRa
  • SimRa Mode – check if you are connecting the Openbikesensor with the SimRa App

Privacy Zones

You could set as many privacy zones, as you like, including their own radius. In the Privacy Options you define how your OpenBikeSensor behaves while inside a Privacy Zone.

WiFi Settings

The OpenBikeSensor can connect to an available WiFi if you supply its credentials. This is convenient when you want to stay connected to your local WiFi when configuring the sensor. It will tell you the IP adress to connect to on the display.

To upload track from the Open Bike Sensor directly a WiFi connection with internet access is necessary.

Backup & Restore

Here you can back up the configuration of your OpenBikeSensor to your PC or mobile device. To restore from a saved configuration chose the corresponding file in the menu dialog. Use this option before firmware updates to ensure you can restore your settings if they get lost in the process.

Update Firmware

After downloading the latest release (or any other version, in case you need a special setup), just click on “Update” in the options. Select the downloaded file and click update. The device will automatically reboot after a successful update.

You can directly upload a precompiled binary; the latest release can always be found here.


This button restarts the device into the regular measurement mode and leaves the options.

1.4 - Recording a track

This page is not yet available in English. You might be able to read it in...

  • Deutsch: Aufzeichnung einer Messfahrt

1.5 - Privacy Zones

Privacy zones are an important concept in the OpenBikeSensor ecosystem. They are used in the sensor device itself, but also on the Data Portal, to mask your location in certain areas.

This is a crucial privacy feature. Since uploaded data may become published in the Open Data repository, users may (or actually should) choose to configure these privacy zones to protect their privacy. A bad actor might otherwise be able to find out from the data where they live, work, or frequently hang out.

How privacy zones work

A privacy zone can be configured in the sensor device itself, changing its recording activity, and in the Data Portal, which then uses it to filter data before publishing. Depending on how you use your sensor and what your level of concern is, you might choose either or both of these options.

A privacy zone is a circular area, defined by a center point and the radius, around which data is masked. You should set up multiple of these zones at relevant locations, so that bad actors cannot identify where your tracks start and end:

  • Your home
  • Your workplace
  • Your friends' homes
  • Anywhere you frequently ride your bike or regularily hang out

Recording modes

There are 4 modes of operation for the OpenBikeSensor:


Which one to choose

The settings inside the OBS are applied as it records the data. So anything not recorded due to a privacy zone and the privacy setting will never be available to anyone, not even you, when you take out the SD card from the sensor and transfer the files to your computer.

If you want to have your own data, but not publish them, consider putting the privacy zones into the Data Portal instead. While this means you have to trust the Data Portal software to do its job properly (and nobody will guarantee that it does, but we promise to try our hardest), it allows you to download the unmasked data from the portal yourself.

A third option is to never upload the data from your OBS directly, but instead move the track files to your computer and use a script to privatize the data before you upload it from there to the Data Portal.

The safest option of course is to never upload your data at all. But then, what are we building a sensor for?

One more difference between configuring the privacy zones in the OpenBikeSensor versus the Data Portal is that the sensor does not retroactively apply the privacy settings. So if you forget a location, or did not choose the right recording mode before you went for a ride, the data is already stored in the track. The Data Portal however reapplies your privacy zones whenever you change them, to all your past (and future) tracks. Though you have to remember that once your data is published into the Open Data repository, anybody might have downloaded a copy already, and you will never be able to take that back. You should always review your settings before you publish!

Privacy in the OBS ecosystem

Why we shift privacy zones

If you publish multiple tracks with anonymized data, anybody will be able to reconstruct the privacy zone from the published data. The tracks going from and to the private place inside the privacy zone will be cut off at the boundary of the zone. If you ride your bike into different directions, away from your private point, it is possible to mathematically redefine the circle that you used to cut off the tracks.

Therefore, it’s not advisable to put your privacy’s center point right on the location you don’t want others to know. In the OpenBikeSensor, you have the option to manually shift your privacy zone into a random direction. You should only do this once for each zone. You can also use any external map tool and manually find center coordinates for your privacy zone that seem reasonable to you, but are not exactly your private location.

In the Data Portal you can place the circle manually on map, in a way that it contains your private locations. Or you provide the actual private location and let the app choose a random offset. Both ways allow you to visually review your shifted zone before saving.

By the way, for the same reason as above, you should not change the offset of your privacy zones too often. Otherwise, it’s possible to reconstruct many circles from the data, all of which will contain your private location. This would defeat the purpose of shifting the privacy zone in the first place, as it reduces the size of the area that probably contains your private location. Kind of counter-intuitively, it reduces security instead of adding to it!

1.6 - Upload tracks

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2 - Hardware

This section documents the possible sensor configurations you can build for yourself, and also provides instructions what you need to purchase and how you are able to build your own OBS.

Starting out, make sure to check out the model selection to figure out which version of the OBS you want to build.

If you plan to build multiple OBS it is recommended to first print and fully assemble one version. In the past sometimes suppliers have slightly changed dimensions of parts they deliver. If you notice that before you print a bunch of cases it can still be fixed in the model. In that case mention it in the [Community](/en/community/. This allows us to adapt supplier lists or the case as needed.

Next up, you will need to figure out all the parts that you need to purchase or create for your selected model. This includes a lot of electronic components, a PCB, the 3D printed case and fixtures, wires and fasteners. Check out the detailed BOM for your version.

We also provide instructions here on printing your own cases, ordering PCBs from your favorite manufacturer, and for assembly of the sensor from all the parts.

Note: This website is still work-in-progress, and some parts of the documentation are not complete. If you run into trouble, ask in the Community. Don’t expect a smooth experience just yet – but we’re working on it. However, don’t fear, while not necessarily straightforward at all times, it is still very much possible for beginners to complete this build and construct their own OBS.

Construction kits

Because the OpenBikeSensor consists many parts from many different sources, bulk orders organized by local groups are advisable. Head over to Community if you want to organize or paricipate in a bulk order.

OpenBikeSensor Construction Kit (old version)

3 - Acknowledgments

We stand on the shoulders of giants.

The development of the OpenBikeSensor would not have been possible without the work of countless other people who, like us, chose to publish their work and make it available for everyone.

While we cannot list everything we build upon, here are some honorable mentions that we would like to acknowledge, either because they are obscure and little known but deserve publicity, or have tremendous impact on our project.

In no particular order: