Karoo Forumslader extension

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fezu54

• June 09, 2026 19:31

Hi everyone,

I wanted to share a new extension I’ve been developing for the Karoo 3 that integrates data from the Forumslader directly into your data fields.

 

What is the Forumslader?

For those unfamiliar, the Forumslader is a highly efficient DIY/custom-built charger and battery system for hub dynamos (details here: https://www.forumslader.de/ ). It is a staple gear choice for long-distance cyclists who need reliable energy harvesting while riding.

 

Background & Inspiration

After years of navigating exclusively with a smartphone, I eventually moved to the Karoo because it was the only bike computer that offered a comparable experience in terms of display quality and UI performance. While the Karoo's shorter battery life can be a drawback for long tours, combining it with the Forumslader completely eliminates that issue.

This extension brings that setup together, inspired by the existing Forumslader Companion App for Garmin devices (https://github.com/cyberman54/Forumslader-Companion ). I wanted to ensure the Hammerhead ecosystem has the same critical integration using the Karoo SDK.

By pulling this data onto the screen, it essentially transforms the Karoo into a better Coros Dura – making it the ultimate setup for self-supported, multi-day bikepacking trips.

 

Current Features

The extension currently provides dedicated data fields for:

• Battery Status: Keep an eye on your buffer battery percentage.
• Consumer Electricity: Monitor the live power draw/charging state.
• Current Speed: Dynamo-calculated speed data.
• Current Trip Length: Tracks distance covered (in kilometers).

 

Project Link & Feedback

The project is open-source and under active development. You can find the code and latest releases on GitHub:

👉 GitHub Repository:

https://github.com/fezu54/karoo-forumslader 

 

Roadmap

I plan to expand the available data fields as development continues. Upcoming additions will include:

• Ambient temperature
• Current gradient
• Additional power/voltage metrics

Check out the repository, try it out on your next tour, and feel free to submit feedback or feature requests via GitHub Issues!

Cheer's and happy riding!

3

• 

  Andrew Arnold

  • September 11, 2026 21:51

  Wie kann man den Forumslader mit dem Karoo 3 koppeln? (Info bitte für nicht IT Freak😉)

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  fezu54

  • September 12, 2026 21:42

  1.  APK herunterladen: https://github.com/fezu54/karoo-forumslader/releases
  2. Per Companion App an Karoo senden und installieren
  3. Wichtig: Einmal die Extension öffnen und die angefragten Berechtigungen bestätigen
  4. Forumslader als Sensor verbinden: https://support.hammerhead.io/hc/en-us/articles/25181289784091-Karoo-OS-Pairing-Sensors

  Ab dann sollte der Karoo den Forumslader automatisch erkennen sobald dieser angeschaltet ist.

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