badhorsy

I'm using a Garmin Edge 800 with the speed/cadence sensor.

Is there anyway to explicitly check whether a spoke magnet is working or not (since if it doesn't, the speed will still register through GPS)?

I tried resetting the unit (by holding down the outside button). When I do this, the unit flashes red whenever the cadence magnet moves past it, but does not flash when the spoke magnet passes it. The spoke magnet is easily within range though, and passes very close to the arm.

Is something wrong?

svtmike

The spoke magnet should cause a green flash of the LED on the pickup after a reset.

Smallguy

my 705 speed sensor recently became erratic I have tried everything on the garmin forums besides replacing my unit

in my case I believe the Reid switch is damaged because my speed goes form zero to 32 to 64 km

try the garmin forums it maybe a common issue for the 800

I just do not care enough about speed indoors to buy a new sensor till the cadence stops working too

RacerOne

I don't have a Garmin but couldn't you just spin the wheel with the bike setting still?

Breal

I have had this issue a few times with the sensor not working for speed, for cadence or just not at all. Just call garmin and they will replace it for you at no charge. Just tell them the issue.

cons

I had to push the spoke magnet off center of the combo speed/cadence sensor. This made it work for some reason

Nachoman

If your edge is displaying cadence then the magnet is working.
Also, when you first turn on the unit, it should very briefly display something like "speed sensor detected".

grwoolf

Not sure about the 800, but on my 500 I can disable the GPS and force it to use the wheel speed (from garmin speed/cadence sensor). I assume the 800 has the same thing. With the GPS disabled, if you are getting cadence and not speed with the magnet set up right, it's a problem with the sensor.

Gearhead65

+1

chasmm

Not necessarily true. There are two distinct sensors in the GSC10 unit. The GSC10 can transmit cadence without speed (and vice-versa).

I don't have the GSC10 manual handy, but I believe there is a red/green LED for verifying that the sensor is picking up the magnet passing. As others mention, the easiest way (other than the LEDs on the GSC10, which can be difficult to see) is to disable GPS on the head unit, then spin the wheel.

FLvector

+1 Lift the rear wheel, spin the pedals and watch for the speed and cadence change on the garmin. The red is easy to see on the sensor, the green, not so easy.

rdtompki

It's also possible that the battery in the GSC10 is weak. I might try a new battery before I started working a replacement with Garmin.

kenl666

I don't have access to my bike right now, but I seem to recall that there's an alignment groove on the end of the speed sensor arm. Make sure that the center of the spoke magnet is aligned with that groove, not centered on the sensor arm.

When I first installed mine, I remember that I had to move the magnet out farther than one would intuitively think before the speed sensor would pick it up. I think the proper alignment results in part of the magnet 'hanging off' the end of the sensor arm.

If the cadence sensor is working I doubt that a new battery is needed.