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False Garmin data.....?

millstermillster Posts: 209
Went for a ride after work this evening, and the data can be seen here:

http://connect.garmin.com/activity/162176763

So, the ride apparently was 45.28 miles @ 26.3mph. In reality the ride was ~33/34 miles @ ~18.8mph (Leeds->Harrogate and back-17 miles each way).

I can't fathom how the Garmin has mapped the ride correctly, but come back with an exaggerated mileage. I did notice that it was returning speeds of >50mph on the downhills, and similarly speeds of around 20mph on the long drag up that I know I never usually exceed 12/13mph.

I've never had problems such as this before (granted, I haven't been using it long), so do I assume that this is a one ride gremlin that will disappear or does it suggest that the speed sensor is mounted incorrectly/faulty?

Posts

  • John.TJohn.T Posts: 3,698
    edited March 2012
    Have you set the wheel size to 'custom' and the correct size. Using 'auto' can throw up some anomalies.
    Check the wheel magnet is set right. Better just past the mark than the other way and also not too close.
  • p.ilchardp.ilchard Posts: 16
    I see you're using a Garmin 500 GPS, I was thinking of getting one now I know I will. Congratulations on exceeding 70 mph too.
  • millstermillster Posts: 209
    some more ride data from this evening:

    http://connect.garmin.com/activity/162782071

    This ride is no more than 16/17 miles. Speed is out again as well. Wheel size has always been set at 2096-this is driving me mad! Only other potential reason I can think is whether the battery in the cadence/speed sensor is low?
  • amaferangaamaferanga Posts: 6,789
    It's also possible I believe to have the speed sensor and magnet misaligned such that it triggers twice per revolution. Have a search on the Garmin forums and you'll probably find an answer.

    Or just remove the wheel magnet - GPS speed is fine unless you spend all your time under trees.
    More problems but still living....
  • maddog 2maddog 2 Posts: 8,114
    this may be a muppet question... but why do you need a speed sensor anyway? The 500 is GPS so it tracks speed automatically...

    Having said that, is the speed sensor on the front or rear wheel? If its the rear then the cadence magnet may be setting it off...?
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • John.TJohn.T Posts: 3,698
    maddog 2 wrote:
    this may be a muppet question... but why do you need a speed sensor anyway? The 500 is GPS so it tracks speed automatically...

    Having said that, is the speed sensor on the front or rear wheel? If its the rear then the cadence magnet may be setting it off...?
    A sensor is more accurate. All sorts of things like trees, buildings etc can affect the GPS. It is good but not infallible.
    Sensor is on back wheel but there is no way the cadence magnet will affect it.
    I suspect the OP has the wheel magnet set wrong and is getting some double hits.
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