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Passing over highway on bridge, drops speed, why?

roccolord
over 6 years ago
On my final stretch of road on many rides I pass over a highway, on a bridge (It's a sprint to the city limit sign, so it's really annoying to get freak stats). Every time speed just drops when passing over the highway, I have attached a screenshot from garmin connect displaying the problem I'm facing. I have the Garmin 1030, I also have the Garmin Speed Sensor connected (PART NUMBER: 010-12103-00). Why is this happening especially with the speed sensor?

Can anyone from Garmin or other person with perfect brains explain this?

This forum doesn't work properly, it's not possible to attach files in any way or form.

Here is a link to the picture: http://x0.se/dropspeed.png ciq.forums.garmin.com/.../1338833.png
  • 0 over 6 years ago
    Well it's not possible to upload it here.... Looks to be all sorts of problems with this forum...

    Your file of 284931 bytes exceeds the limit of 3058. 2648891419.fit


    The forum just doesn't want to host lots of big files.

    You managed to host (store) the image on another site.
  • 0 over 5 years ago
    This happened again on ride yesterday:
    https://connect.garmin.com/modern/activity/2677428922

    1:19:38 into the ride, I drop 10km/h when passing over the motorway. Speedsensor connected, gps connected everything running as it should. Device thinks I change from standing to sitting around that time in the activity, I'm not I'm standing up all the time, until that watts drop at 1:19:41
  • 0 over 2 years ago

    I just noticed this topic.

    Not sure if roccolord still have this problem.

    Do you have this on several bridges, or is it always the same bridge ?

    I have noticed this problem also, but only on one specific bridge, the Waalbrug in Nijmegen (the Netherlands).

    Suddenly the speeds goes from almost 30 km/h to 10-15 km/h.

    Had this problem in the past on my Edge 800, but noticed it lately also on my Edge 1030 while crossing the river

    It looks like there is some source that is disturbing the ANT+signal.

    Don't know how/what the source of this disturbing signal is.

    Donald

  • 0 over 2 years ago

    You should see what happens when you have large trees left and right off the road.  Even segment time is wrong. I got completely different numbers when I put a speed sensor on. My performance increased by 10 % or more.  No one tells what reception is under tree canopy. All the numbers you see are estimated. Before speed sensor variation in speed 5 to 6 percent on a straight line. After sensor hello smoothness.

  • 0 over 2 years ago in reply to CostasGram

    The problem I noticed is with speed sensor, so there must be some source of disturbance in/under/above the brdige which makes my speed 'crazy'

    DOnald

  • 0 over 2 years ago in reply to donaldgroen

    …from here:
    https://support.garmin.com/en-US/?faq=9NL91YJSJd3Tnyif9jRSy6

    The BSS (Bike Speed Sensor) contains a magnetometer that measures the three dimensional components of the ambient magnetic field (similar to an accelerometer measuring acceleration). As the wheel rotates, the magnetometer measures its own rotation within the surrounding earth's magnetic field.

    If it is a bridge made of steel or ferroconcrete it is possible that the ambient magnetic field is disrupted.