edge 500 speed jumping about

theboykidney
theboykidney Posts: 95
edited January 2014 in Road general
Been a few months since i've been on the bike and had to coax my 500 back to life a little bit in preparation.
Now however when I'm stopped the speed is jumping around a bit like its getting speed from GPS only, and not the speed sensor. Pretty sure before I got into my Christmas boozing and shunned the bike it used to read zero when still, as if it was only taking readings from the speed sensor.
Am I going insane or is there some way to force the speed sensor? maybe the glitch waking it up reset something?
Cheers

Comments

  • desweller
    desweller Posts: 5,175
    Flat battery on the sensor? It might not like the cold. My old-fashioned wireless sensor was not happy today.
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  • smoggysteve
    smoggysteve Posts: 2,909
    When using the GPS you only ever get speed from GPS and not the magnet. it only uses this when signal is lost. it will use gps to calibrate your wheel size but you never get your receiver using both to calculate speed. Do you take any other gadgets including phones with you that could ne causing interference? I remember putting an old Sigma computer next to my iphone and it went crazy even though they were in no way connected. Try changing your units recording from smart to every second or vice versa.
  • chris_bass
    chris_bass Posts: 4,913
    SmoggySteve wrote:
    When using the GPS you only ever get speed from GPS and not the magnet.

    I'm pretty sure that's not true, If you stay still, lift the back wheel and spin it the speed will go up, I think if it detects a speed sensor it uses this as default and use GPS to plot the points so you can see the route after.
    www.conjunctivitis.com - a site for sore eyes
  • smoggysteve
    smoggysteve Posts: 2,909
    Chris Bass wrote:
    SmoggySteve wrote:
    When using the GPS you only ever get speed from GPS and not the magnet.

    I'm pretty sure that's not true, If you stay still, lift the back wheel and spin it the speed will go up, I think if it detects a speed sensor it uses this as default and use GPS to plot the points so you can see the route after.

    It will display it, but if you upload your track it will not be part of it.
  • chris_bass
    chris_bass Posts: 4,913
    SmoggySteve wrote:
    Chris Bass wrote:
    SmoggySteve wrote:
    When using the GPS you only ever get speed from GPS and not the magnet.

    I'm pretty sure that's not true, If you stay still, lift the back wheel and spin it the speed will go up, I think if it detects a speed sensor it uses this as default and use GPS to plot the points so you can see the route after.

    It will display it, but if you upload your track it will not be part of it.

    a couple of months ago I didn't line up the speed sensor magnet and it showed a top speed of 90 odd miles an hour and this also shows on my Garmin connect site
    www.conjunctivitis.com - a site for sore eyes
  • smoggysteve
    smoggysteve Posts: 2,909
    How does one incorrectly aligned magnet show false speed faster than normal exactly? if you stuck more than 1 magnet on I could understand but a rotating magnet misaligned suddenly makes your readings 2 or 3 times faster......
  • ddraver
    ddraver Posts: 26,611
    SmoggySteve wrote:
    Chris Bass wrote:
    SmoggySteve wrote:
    When using the GPS you only ever get speed from GPS and not the magnet.

    I'm pretty sure that's not true, If you stay still, lift the back wheel and spin it the speed will go up, I think if it detects a speed sensor it uses this as default and use GPS to plot the points so you can see the route after.

    It will display it, but if you upload your track it will not be part of it.

    Yes but the number in the box marked speed is the one from the back wheel sensor. (you can tell as the speed on my GPS is never 0, it always jumps around between 0.7 and 2.0 unless it's registered the presence of the sensor)
    We're in danger of confusing passion with incompetence
    - @ddraver
  • belpersnapper
    belpersnapper Posts: 9
    I had a similar problem with my 305 on the turbo
    Now I have a 500 and the issue of ridiculously high speeds has gone but the speed keeps dropping to 0.0 every few seconds when using it on the turbo.
    Auto pause off
    GPS off
    Using Garmin cadence sensor with new batteries
    Not got the answer yet I'm afraid
  • chris_bass
    chris_bass Posts: 4,913
    SmoggySteve wrote:
    How does one incorrectly aligned magnet show false speed faster than normal exactly? if you stuck more than 1 magnet on I could understand but a rotating magnet misaligned suddenly makes your readings 2 or 3 times faster......

    I have no idea, but put it right and speed went back to normal, i'm not sure if the magnet actually hit the sensor and that did something?
    www.conjunctivitis.com - a site for sore eyes
  • gavt0333
    gavt0333 Posts: 95
    The speed sensor is a very flimsy magnetic reed switch that can get damaged very easily. If you search for "garmin cadence working but speed not" you will see lots of folk having this problem. I think mine hit the magnet a few times at one point on the turbo and that was it gone.

    There is a bodge where you open up the casing, solder a new reed switch to the wires then glue it back together. Tried it yesterday but it seems there is no signal actually going through the wires which you can test by touching them together and the green light should still go on. So I ordered a cheap one from decathlon as garmin will only replace within the one year warranty and it seems this is likely to happen fairly frequently. Surprisingly poor quality from garmin the and poor customer service.

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