KAROO Gear Indicator Project (Mechanical Gears)

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Marcus Mason

• April 09, 2026 21:03

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.

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  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

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  Marcus Mason

  • April 12, 2026 22:31

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

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