Measuring speed with GPS during snowboarding

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István
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Measuring speed with GPS during snowboarding

Post by István » Tuesday 16 March 2010, 18:38

Have you guys already tried it? I'm almost sure you have. What were the results you got?

I do not want to have a pissing contest here, so I'll not post mines this time, but I got some really scary results that I have not expected and just want to check if those results are in the range of what you measured.

I used a Garmin GPS, don't ask me the model, it was small, yellow and waterproof / shock resistant - some tracking stuff a friend of mine gave me. The place I tested was in Livigno, Carosello side, hero snow, no people, perfect visibility.

I calibrated the thing when I was in my car and it looked really accurate.

During riding I checked what the top speed was in different riding styles, i.e.:
- EC with nicely controlled speed
- Speed carving (not fully laid extended turns like EC, but laid on both sides with a good rhythm, empty red slope, decent speed)
- Moderate speeding (what one would do when feel tired to carve and just lets the board go until you reach the lift - but nothing crazy, I would say the speed you need on the bottom of Barthelemy not to get stuck on the short uphill part)
- Speeding (when you feel the slope is perfect, there are no people around you and there is big enough space to stop before you hit the lift)


What were your results? What do you think your results would be, if have not tested yet?

Anyone can elaborate on the potential inaccuracies of such a GPS device? (vertical speed, curves, etc)


Thanks

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Post by Hans » Tuesday 16 March 2010, 21:10

Istvan :evil2: , I don't need a GPS to see you're scary bloody fast since I have seen you a couple of years ago in Grimentz...

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Post by The Blitz » Tuesday 16 March 2010, 22:00

Google Translate...
viewtopic.php?t=3267
 - 168XH Pro - Custom Dual 168H - Swallow Undertakeur 185

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Post by István » Wednesday 17 March 2010, 8:15

Thanks Blitz. Although I did not understand the full article, I saw the chart that indicates speeds. Those 2 values are apparently in line with what I measured.

Well, here are the speeds I measured (I had the GPS all day with me and I checked top speed after each and every run, so the below values are averages / ranges)
- EC: around 40 km/h
- Speed carving: around 60-65 km/h
- Straight-lining to the lift: 80-90 km/h (no crazy speeding, just letting the board go a bit at the end of the slope)
- Speeding: 100+ km/h
- Top speed I measured: 126 km/h

As for the top speed, I got really scared when I saw that a small speeding can take you up to 80-90 km/h, so after that I was not pushing too hard to test the max, so I am sure someone with balls could easily do more.... :wink:

So all in all I got really scared and will revisit the idea of protection and a helmet. Currently I use none.... :roll:

And the usual disclaimer: these speeds have been measured under extremely nice conditions, hero snow, practically empty slopes, 100% visibility. I've done it at my own risk and I suggest you do not try testing your speed limits as it may lead to serious injury or at least brown pants. I'll not specify here the boards I used, but those who know me will know. :twisted:

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Post by starikashka » Thursday 18 March 2010, 11:05

Istvan :-) despite that you menioned that you do not want pissing contest here it could happen after you published your results. Do not worry...Softbooters can make 160 kmh and there is a video in YouTube :-)

GPS device has to be of a good quality and understand fast altitude changes. I`m not sure portable car or tourist GPS can do that.
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Post by István » Thursday 18 March 2010, 16:30

I used a device developed for tracking. It looked pretty accurate when testing it with my car.

On the other hand I also agree that it might be inaccurate.

But if you think about it, if it is inacurate then it would show lower speeds for 2 reasons:

1) The GPS measures distance between points versus ellapsed time. Therefore it assumes a straight line of travel as opposed to reality that is a curved line. The faster the sampling, the smaller the error.

2) I am not sure wether it accurately calculates speed in 3D knowing that we do not travel on a flat ground but we also have a vertical speed. If it assumes that we only travel on a flat surfac and misses vertical speed then it again would show a lower speed (just think about a 90 degrees triangle, it would measure the horizontal side of it, while one would travel on the hypotenuse)


I'm interested if anyone else has experience with measuring speed with a GPS, so please do let me know.


Kindest

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Post by pokkis » Thursday 18 March 2010, 16:37

I once hit 32km/h but my pulse was 185beats/min 8O
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Post by István » Thursday 18 March 2010, 16:42

I saw you... :liar:

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Post by starikashka » Thursday 18 March 2010, 19:37

István wrote:I used a device developed for tracking. It looked pretty accurate when testing it with my car.

On the other hand I also agree that it might be inaccurate.

But if you think about it, if it is inacurate then it would show lower speeds for 2 reasons:

1) The GPS measures distance between points versus ellapsed time. Therefore it assumes a straight line of travel as opposed to reality that is a curved line. The faster the sampling, the smaller the error.

2) I am not sure wether it accurately calculates speed in 3D knowing that we do not travel on a flat ground but we also have a vertical speed. If it assumes that we only travel on a flat surfac and misses vertical speed then it again would show a lower speed (just think about a 90 degrees triangle, it would measure the horizontal side of it, while one would travel on the hypotenuse)


I'm interested if anyone else has experience with measuring speed with a GPS, so please do let me know.


Kindest
This issue is better to be discussed with GPS vendor. Those devices can use illinear algorithms for speed calculations. Do not know. But it`s really old issue :-) many guys have measured their speed on snowboards and then check with vehicle and say..o shit, i`m a cool guy :-)

Do not spend your time on it as you do not need any measurement device for showboarding...There is a certain muscular ring that squezzes stronger than higher speed is :-) that is most accurate speedometer...When you reach a pokkis age you are getting advanced option of measuring a speed by beats per second, because that device you used before have weared out and do not keep even a sand and gas inside of you :-)

:-) :-) :-)
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Post by István » Thursday 18 March 2010, 20:29

I think you just explained the meaning of the English phrase 'old fart'....

I think measuring the speed is good for one thing: makes you realize how dangerous this thing is. It will not make you cooler, no way.

Actually when we took the GPS up the hill we agreed that the fastest will be granted the "Dickhead of the day" title. And I won... :?

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Post by pokkis » Thursday 18 March 2010, 21:01

Agree with Istvan, this gives good indication of dangerous situation we might get due speed. Folks dont alwas realize speeds we will get on slopes.
So please were proper protection on slopes
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Post by Abrax » Thursday 18 March 2010, 21:37

Hi guys, what I have to add is that we are taking two looong razors with us wherever we go... Sometimes it means two +100km/h razors at once. Deadly weapon...

Pokkis, doesn't matter how fast, what does matter is the quality ;)
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580km in 3 hours and 5 minutes completely legal!!! I love german highways!!!

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Post by starikashka » Friday 19 March 2010, 10:40

I do not need to measure my speed to understand the risk...i know already
but the contest is great idea :-)
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Post by xyxx » Friday 19 March 2010, 12:04

István wrote:I think you just explained the meaning of the English phrase 'old fart'....
Spot on.

Thanks for the post, it is very much sobering information indeed

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Post by Alexey » Monday 22 March 2010, 9:57

István wrote:And the usual disclaimer: these speeds have been measured under extremely nice conditions, hero snow, practically empty slopes, 100% visibility. I've done it at my own risk and I suggest you do not try testing your speed limits as it may lead to serious injury or at least brown pants. I'll not specify here the boards I used, but those who know me will know. :twisted:
http://carving.noredirectionallowed/Video/The_Final_Ride.wmv

:-)

p.s. Custom board 151 cm / 147mm

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