Why do so many pro bikes seem to have old school magnets on the wheels, presumably for a computer? Why not GPS?

Cadence sensor magnets?

Garmins still use the magnet on the wheel for speed as well as the GPS… I assumed for better accuracy or GPS dead spots but never bothered looking it up

Cadence sensor magnets

Think about that.

I can’t say I’ve ever noticed. They’ve all got GPS ‘sticks’ on the saddle. Current Garmin sensors don’t use magnets, and I’ve never noticed them using those either.

Some computers predict or like to know what gear you’re in so with the combination of a pedal cadence sensor and wheel speed sensor the computer can work out your gearing and no doubt tell you all sorts of data and intelligence. Though gamins latest speed sensors wrap around the hub and look alot neater.

The “sticks” are data transmitters for things like cadence, power, heart rate. Dimension Data handle this and pass the information on to the organisers and it then gets passed on to broadcasters, etc. http://www.cyclingweekly.co.uk/news/racing/tour-de-france/what-is-the-black-stick-below-the-riders-saddles-at-the-tour-de-france-182440

Magnetic motors obvs. 😆

Srm power meters need a speed sensor, and the sensor that comes with one uses a magnet

Garmins still use the magnet on the wheel for speed as well as the GPS… I assumed for better accuracy or GPS dead spots but never bothered looking it up

Actually the newer Garmin sensors do away with the magnet and use accelerometers:

As above – some power meter systems (most notably SRM) don’t rely on GPS for their dist/speed measurements.

If you look at the Sky bikes, for example there will be no magnet as the Stages uses an accelerometer in the crank for cadence and the garmin gps for speed/distance.

Speed sensor is more accurate and responsive than GPS. Also, as said, many head units don’t do GPS.

Thanks team – I am now a wiser man 🙂

I forget that SRM are still basically selling a 20 year old product 😆

Their pricing also still seems to reflect their position in the marketplace 20 years ago!

Some teams are sponsored by companies who’s head units do not have GPS. They need the sensors to determine distance traveled over a stage.