Cycling Speed and Cadence Sensor

No problem! Yes, it could be quite a good project. It seems the code is there:

https://github.com/espruino/BangleApps/blob/master/apps/cscsensor/cscsensor.app.js#L158-L159

But I think it must be getting it from the wrong place in the data string (eg getUint16(1, true) should be something other than 1) because that's the same place wheelRevs comes from.

https://learn.adafruit.com/bluetooth-bicycle-speed-cadence-sensor-display-with-clue?view=all might be handy as a primer

Actually I think what's happened is the original app was designed thinking that if the crank speed bit was set, the whole advertising packet only did the crank. But what it really means is that there's wheel and crank data.

It's really hard to read, but here's the spec: https://github.com/oesmith/gatt-xml/blob/master/org.bluetooth.characteristic.csc_measurement.xml

So I think just changing to:

        const crankRevs = event.target.value.getUint16(7, true);
        const crankTime = event.target.value.getUint16(9, true);

might fix it