Garmin Bike Speed/Cadence Monitor (GSC 10)

Performance cyclists know it's more efficient energy usage to maintain a set cadence than chase a set speed over varying terrain; the GSC 10 makes it easy. Since it mounts to the left chain stay, you can use it either riding outside or indoors on your trainer.


The GSC 10 attaches easily to your bike, where its sensors detect signals from your wheel and pedal and sends the information wirelessly to your personal trainer/cycle computer. This kit comes in three basic parts; a sensor unit, which is about the size of a matchbox, and two magnets about the size of your pinky nail. Several zip-ties are included to mount the sensor to the left chain stay.

Installation is straightforward, but do follow the directions carefully and don't snug down the zip-ties until you're sure you've got all three components just where you want them and have tested the system. The spoke magnet clamp has both a round hole and a square hole; make sure you use the right hole for your spoke profile.


Testing is accomplished by pressing a small button on the sensor unit, which prompts it to flash a red LED, then a green one to indicate that testing is started. Once the test button is pressed, the next 60 revolutions of the crank should cause the red LED to flash when the crank magnet passes the sensor, while the spoke magnet passing the sensor should generate a green LED flash. If you saw the red/green flash when the button was pressed, but don't see a flash as each magnet passes the sensor, chances are:

  • one or both magnets are not properly aligned with the sensor (there are alignment lines on the sensor and both magnets), or
  • the magnets are passing too far from the sensor, or
  • the window for testing has expired after 60 revolutions of the crank from when the small button on the sensor unit is pressed.

Note: This item contains a lithium battery and cannot be shipped to APO, FPO, US Territories, Hawaii, Alaska, or international destinations.

    GSC 10 is compatible with the following devices:
  • Colorado 300, Colorado 400c, Colorado 400i, Colorado 400t, Dakota 20, Edge 305, Edge 500, Edge 705 and Edge 800
  • Forerunner 305, Forerunner 310XT, Forerunner 405, Forerunner 405CX, Forerunner 410, Forerunner 50, Forerunner 610, Foretrex 401 and FR60
  • GPSMAP 62, GPSMAP 62s, GPSMAP 62st
  • Oregon 300, Oregon 400c, Oregon 400i, Oregon 400t, Oregon 450, Oregon 450t, Oregon 550 and Oregon 550t
  • Etrex 30, both Forerunner 910XTs, Montana 650t, Montana 650 and Montana 600


  • Item #61705
  • Battery: CR2032
  • Batt life: 1.4yr (1hr/day)
  • Range: 3.0 m
  • Water Resistance: IPX7
  • Length: 5.1 cm
  • Width: 2.3 cm
  • Height: 3.0 cm
  • Weight: 25 g
  • In stock / $85.00

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