Review: Garmin Speed and/or Cadence Sensors for Bikes

Garmin Speed, Cadence and GSC-10 Combined Sensor
Speed cadence box to the left and the GSC-10 to the right

Garmin’s GSC-10 has been their mainstay, magnet-based speed+cadence sensor for several years. Relatively recently, newer versions were introduced that do not require magnets. Namely a speed-only sensor and a cadence-only sensor. They are ANT+ only, are mostly self-calibrating and do what their name suggests.

Positives: They are accurate and reliable. Because these new ones are held by a rubber band to  the crank (cadence sensor) and wheel hub (speed sensor) they are easily interchangeable between bikes. They no longer require a magnet. Installation really takes a matter of about 1 minute – which is much more favourable to the previous situation with the GSC-10 which essentially required one sensor per bike.

Negatives: As the market leader, many Garmin products are priced at a premium to the competition.  These are no exception; although the old GSC-10 is now generally ‘fair value’.

Comments: Although breaking a band might mean a lost sensor; the band is designed so that it would probably have to break in two places before it fell off. Hopefully you’d notice it before that.

If you have a specific turbo-wheel then the wheel and sensor can easily be changed between bikes for indoor sessions. When testing with the WAHOO FITNESS APP (a product that is one of the best ones) there were sometimes issues with confused signals between these two sensors and power meter signals. I never quite got to the bottom of this but also experienced a similar issue with 4iiii’s app, implying that there could be an issue with the Garmin sensors in ‘unusual’ hardware configurations. Having said that compatibility with Garmin watches/head units is perfect in my experience.

Calibration is automatic (based on GPS) for the speed sensor on most Garmin devices. Manual calibration will require tyre circumference. The cadence sensor requires no calibration and is ‘good-to-go’ once fitted and paired.

I occasionally use software that only allows me to have 3 sensors so when I want a HR monitor, cadence sensor, speed sensor and power meter I have to get creative! (Revert back to the GSC-10!)

Interestingly this sensor will work on some high-end running watches such as the Garmin 620. So, ignoring expensive-to-obtain power data, you can probably use your running watch for occasional cycling.

Alternatives: If you want to spread your cash to non-Garmin companies it will be tricky. You could try the WAHOO BLUE SC but that product is essentially the same as the GSC-10. Many power meters now also supply cadence data – you might not need these sensors.

Verdict: Very handy but a tad pricey.

Detailed Review: n/a

Garmin Speed/Cadence GSC-10$45.50Link£27.15Link
Garmin Speed/Cadence 12104 £43.78Link
Garmin Speed Sensor £28.61Link
Garmin Cadence Sensor$35.50Link£32.54Link

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3 thoughts on “Review: Garmin Speed and/or Cadence Sensors for Bikes

  1. Ordered a “pack version” of an Edge. Had the idea to use the sensors for my girlfriend’s foldable bike. Made the calculation without Garmin. Gnnnaaaahhh. The attached band of the speed sensor is not long enough for thicker (e.g. internal gearing, power supply) wheel hubs. ?

  2. mine came with 3x different sized bands… (maybe it was 2). but, yes, the sturmley-archer type drums will be LOT thicker. You could fashion something yourself with a trip to the stationary shop’s elastic band section (although that material might degrade quite quickly)

    1. Different sized bands: I got those too. But they’re only for the cadence sensor.
      Fashioning myself: Thanks, I will see what works.

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