accuracy of speed measurments while snowboarding

i'm going snow boarding soon and want to use race chrono to plot my routes and also to measure speeds etc. But i'm not sure how acurate it'll be. Does anyone know if the speed will be measured by actual distance travelled with the altitude changes taken into acount, or will it only measure horisontal speed from point to point and not take into account the fact i have traveled half a mile down, but only a few hundred meters across?

Any comments will be welcomed as i really need this to work so i can settle a long standing bet with my brother on how fast we are actually going lol


  • RaceChrono uses the speed GPS reports. I suggest you'd use external Bluetooth receiver attached to your shoulder to get the best plot.

    To your original question, I think it's the horizontal / forward speed only. Don't take this as fact though, because I'm not entirely sure about it.
  • I wouldn't worry too much about the vertical distance when snowboarding. If you go down half a mile and a few hundred metres horizontally, you'll be more worried about what you hit when you fall down that cliff face than the speed you're going at. The Harakiri in Mayrhofen was the steepest slope in Europe a few years ago. That was 78%. So, for every metre you travel forwards, you travel 78cm vertically. It's not even 45 degrees. That's an exceptionally steep slope. An average run is more like 1:3. I used to use Nokia Sports Tracker for skiing as it gives you more useful information than RaceChrono, such as average speed, altitude and the like.
  • SportsTracker is very good for physical sports, but jonboyc specifically wanted to plot his route, which RaceChrono does more accurately in my opinion. SportsTracker does not save all route points for some reason, at least it did not used to do it.
  • interesting!!! If he was racing a slalom course would it actually be useful as performance data?...or more for plotting on google earth?

    If it was a tight course and he used a good 5hz receiver...would it show all the turns Lateral Gs?...and wouldn't you get altitude in the nmea somewhere?

    Anybody have a screen grab of skiing or boarding RC data?

    they are doing it here but not sure how well

  • edited February 2010
    I don't think there's any problem calculating the G forces, or taking performance data. Of course in down hill the speed is a bit underestimated, but not too bad, as Andy said. The error in speed is only 5% underestimation in 1:3 slope (33%), calculated using law of cosines.

    It's just a question how useful the racing oriented data from RaceChrono is for a downhill skier...
  • Skiers will be interested in the lines and apex speeds just like drivers. Of course, with only gravity to accelerate, the exit speed is far more important than entry speed. I forget what sort of speeds I was getting to on skis (according to Sports Tracker) but I think it was somewhere around 50mph when going at quite a pace. I remember it showed 33mph during one fall. I have video of that too!
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