Product Description

The Garmin 010-10644-00 Speed/Cadence sensor (GSC 10) can monitor your pedaling cadence as you ride with this self-calibrating, wireless speed/cadence sensor. It measures and reports your pedaling strokes per minute, providing feedback for optimal performance. Use with the Edge 305 or Edge 305CAD, Included With The Edge 305CAD GPS Plus

Product Details

• Size: Garmin Part #010-10644-00
• Brand: Garmin
• Model: 010-10644-00
• Dimensions: 2.74" h x 2.15" w x 3.00" l, .2 pounds

Features

• Cycling speed sensor for select Garmin wrist-mounted personal trainers and cycling computers
• Self-calibrating, wireless design measures both cycle speed and cadence in pedaling strokes per minute
• Provides up-to-the-minute feedback or captures results for later workout analysis
• Compatible with Garmin Edge 305, Edge 305CAD, and Forerunner 305
• Attaches easily to any bicycle; 1-year warranty

Amazon.com Product Description
A good companion for Garmin's Edge 305 and 305CAD cycle computers and the Garmin Forerunner 305 personal trainer, the GSC 10 monitors your cycling rhythm for up-to-the-minute results and later analysis. The self-calibrating, wireless unit measures both speed (in pedaling strokes per minute) and cadence , then provides feedback to the user for optimal performance. You can later feed the results to Garmin's Training Center software, which helps you tailor your workouts to meet specific goals and objectives.

Like the Garmin heart rate monitor, the GSC 10 attaches easily to your bike, where its sensors detect signals from your wheels and send the information wirelessly to your personal trainer/cycle computer. It's also backed by a one-year warranty.

Customer Reviews

Excellent compact lightweight wireless cadence sensor
Another handy piece of equipment from Garmin!

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 for mounting purposes; the entire kit weighs at most a couple of ounces.

Installation is pretty 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 sensor mounts to the left chain stay with a pair of zip-ties. Garmin thoughtfully added a piece of rubber padding to the bottom of the sensor unit, so it won't rough up your fancy carbon frame or your paint job :)

A single zip-tie attaches the crank magnet to the crank, although I had to use a large (3/4") shim on my FSA crank (which has a curved profile and a hollow back) to place the crank magnet in the proper position for the sensor to "see" it. The spoke magnet clamp has both a round hole and a square hole; make sure you use the right hole for your spoke profile! I mounted mine on a spoke directly opposite the tire valve, just to help keep the wheel in balance.

The sensor unit must be positioned along the chain stay such that it can "see" both the crank magnet as it passes by the cadence sensor (the round part on the side of the sensor unit), and the spoke magnet as it passes the speed sensor (the part that looks like a lever in the picture).

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. As pointed out by another reviewer, the LEDs are hard to see in bright ambient light; I'd recommend testing in a garage if possible. Hi-intensity LEDs would have solved this problem, although I suspect these LEDs were chosen for their low power consumption, so maybe it's a smart design decision after all.

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 (this is the problem I encountered and solved with a shim).

When you're sure everything is in the right places, snug the zip-ties and cut them flush. Then set up a screen (typically the Biking screen) on your 305 to display Cadence in one of the data fields, and go ride!

Design could be improved
The design could be improved upon as you need to have a magnet on both the crank arm and the spoke within 5mm of the sensor. This makes id difficult and may require some minor modifications on some bicycles (I needed to add a spacer between the crank arm and the magnet). Too much tilt towards the crank, risks having the arm of the sensor being caught in the spokes after a large bump on the trails or raod. I have known of other people being able to purchase a larger magnet to the inside of the pedal screw which allows the sensor to be farther appart. Other than that, it works great with the Edge.

Great product, confusing packaging if you have a Forerunner 305
The handlebar mount and cadence and speed sensors went on quickly and worked flawlessly. However, when I first received the package in the mail, I was concerned I had ordered the wrong item. I have a Forerunner 305 wrist-mounted GPS, and all of the packaging for this product references the Edge GPS sensor, so I didn't know whether or not this would even work with the Forerunner. There are very slight differences in navigating the menus to set up the cadence sensor between the Forerunner and the Edge, but the cadence sensor does indeed work very well with the Forerunner, so Forerunner owners order without fear!