KAROO Gear Indicator Project (Mechanical Gears)

Karoo Gear Indicator – Developer Brief I’m looking for developers interested in building a Hammerhead‑native gear indicator app for the Karoo that works with mechanical derailleurs. Because mechanical systems don’t broadcast gear position, the app must infer the current gear using real‑time ride data and known drivetrain specs. Core Goal Create a Karoo data field that displays the rider’s current front × rear gear using indirect sensor fusion and a clean, native Karoo UI. What the App Should Do - Allow the rider to enter: - Front chainring sizes - Rear cassette sprocket sizes - Wheel circumference - Read live Karoo sensor data: - Speed - Cadence - (Optional) Power and gradient for smoothing - Compute the effective gear ratio and match it to the closest known gear combination. - Display the result as a Karoo‑style data field with Hammerhead‑consistent typography, spacing, and colour palette. Technical Requirements - Kotlin/Android app packaged as a Karoo data field - Ratio‑matching engine (speed ÷ cadence × wheel circumference) - Tolerance‑based gear inference - Simple settings screen for drivetrain configuration - Native Karoo UI look and feel (Inter font, black background, orange accents) Outcome A lightweight, reliable, visually native gear indicator that works on any mechanical drivetrain without sensors, using only the Karoo’s built‑in data streams.

Simon Lockwood

April 12, 2026 14:49

This sounds like an extremely difficult task to execute with any accuracy. Even with speed and grade known (not sure how accurate) the steps between gears are very small. Possibly throw in power and cadence data but still sounds tricky. Good luck!!
Simon

Marcus Mason

April 12, 2026 22:31

If executed correctly, it will save me upgrading my BMX to Di2... 😅

Gregory Thomas

September 03, 2026 02:04

Are you still trying to do this? I'm interested in the final product. I can't help with development, but I may know someone that could.
Also, you would only need speed, cadence, and the gears. It would need to be restricted to single chainring applications.

September 05, 2026 06:29

Hi Gregory, I attempted to make the extension using AI, but alas, I have no programming skills and was soon out of my depth. AI thought the extension was possible. On flat ground the prediction would be more constant/reliable; however, gradient and therefore power, and potentially rider weight, would also need to be known. Many variables. If it could be done accurately though.... wow!

KAROO Gear Indicator Project (Mechanical Gears)

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