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Garmin Cadence but no speed

bigaacbigaac Posts: 72
edited February 2014 in Road general
I've had my edge 705 running with the GSC-10 for years with no problems. yesterday i decided to touch my GSC-10 as it looked a little loose, now i've opened up a world of PAIN!!

I've just spend the last hour trying to get it to sync properly, i have cadence recording perfectly but there is NOTHING for speed, it just reads a 0.0mph regardless of the cadence.

I've reset the GSC-10, re-scanned with the Garmin edge but nothing seems to change. I've switched GPS off also (its hooked up the turbo at the moment)

When reseting the GSC-10 i get a red and green flash also, so it seems to be working. I've also replaced the battery so i know it isn't that. I also get a red flash every time the cranks moves over it but nothing when the magnet goes past it, is that normal?

Can anybody shed some light on what i'm doing wrong please?!? :x :x


  • I had that problem with a previous sensor and despite trying pretty much everything ended up replacing it. I read something about the reed sensor being the cause of the problem but never fully got to the bottom of it.
  • GarryboyGarryboy Posts: 344
    Are you sure the wheel magnet is aligned with the sensor (there is a little line on the arm) and close enough?
    I've found them to be pretty sensitive, even if they have only moved a mm or two.

    If it's not flashing green after reset (and your wheel is spinning) it ain't detecting the magnet.
  • SmithsterSmithster Posts: 117
    Just had this problem myself. Turned out that moisture had got inside the arm, which was rectified by removing the arm and letting it dry out.

    Worked a treat and is working fine now. Worth a go if you think it may have got some moisture in it.


  • bigaacbigaac Posts: 72
    cheers guys. tired everything but pretty sure the arm is dead. I've brought it inside to see if it drys out (thanks for the suggestion Smithster) but because i'm so impatient i've bought another GSC-10. if the original one comes back to life i can stick it on the 2nd bike. :D
  • bigaacbigaac Posts: 72
    New cadence sensor fitted this afternoon and all is working again. The arm on the previous sensor was faulty so wasn't registering with the magnet on the rear wheel.
  • A (kind of) related question:

    I've got a Garmin 800 with the rear wheel magnet and cadence sensor. I'm about to put new wheels on for the racing season, but continue to use the old rear wheel in the turbo trainer. I want to keep the wheel magnet on the old rear wheel, because obviously the GPS is of no use to work out speed when you're on a turbo. If I have no magnet on the new wheel, then I should still have a reasonable idea of speed from the GPS, but if I want to increase the accuracy I'd rather have a magnet on there. My question: would I have to buy a new Garmin magnet, or could I use an old Cateye one which is currently sitting on my front wheel for no reason at all?
  • Any magnet will work.
  • BobbinogsBobbinogs Posts: 4,841
    If you are training on a turbo then speed and/or miles are an irrelevant distraction.
  • These sensors are no good for the British climate.
    I`ve just changed my 2nd one in two years. The first failed after getting damp inside. Fortunately it was still under warranty. The second one was just outside of warranty.
    I have sealed the new one as best I could with silicone sealant on every join and where the arm screws into the main body. We`ll see how long this one lasts.
  • Mikey23Mikey23 Posts: 5,306
    I've yet to see a post praising these items for their longevity...
  • John.TJohn.T Posts: 3,698
    Mikey23 wrote:
    I've yet to see a post praising these items for their longevity...
    We just keep quiet about it. I have had 2 since 2010 and have done 19000 miles since. They are not on the winter bike so don't get all the usual winter censored but they have been out in all weathers and have been in use for at least 3/4 of the time. Still fine. That will be the end of that now. :lol:
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