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How fast do you ski and how do you know?

post #1 of 29
Thread Starter 
Quite often on this board I read people making various claims as to how fast they ski but wonder how they make that judgement. I have a portable GPS I carry in my pack which records my maximum speed, it’s rarely more than around 80 kph or 50 mph, even when I’m really flying down a hill, going significantly faster than I, or those I see around me would normally go. Yet I read claims from various people that this is their normal “cruising” speed.

I recently skied with a guy in Canada whom we clocked at over 110 Kph/70 mph (you know who you are). To get this speed he had to make the first chair and basically straight line a groomed black diamond run. Impressive, but it did take some effort. So I’m left wondering about the validity of people’s claims. Are they going as fast as they think they are, and how do they know?

Oh for the record, I’m not much into speed myself, so no it wasn’t me breaking “the ton”. Short turn Pete I’d say, sometimes open it up to get over a flat section further up, other times ... well yeah sometimes just for the hell of it!

Cheers,

Pete

[ February 16, 2003, 10:35 PM: Message edited by: Pete ]
post #2 of 29
If you ride a road bike and are familiar with what various speeds feel like, then you can get a good approximation. For example, normal training pace is about 32 km/hour (18 mi/hr) and I can easily hit 60 km/hour on my bike down a steep grade (especially so in a peloton) so I somewhat know what it feels like on skis. Can't say exactly what my speed is, though, because snow feels different than pavement, and I usually make sweeping GS turns on my skis, while on a bike I am riding straight. I can't imagine doing 70 miles/hour like your friend claims on a non-closed course. I hope he knew for sure that no one else was in the vicinity.
post #3 of 29
Yep Pete - my Thredbo instructor (one of) swears that I just CAN'T go too fast on High Noon - he says if he tucks it he cannot get over 80kph...

Unfortunately I have yet to convince myself that I want to get anywhere NEAR that speed....

I just keep telling myself that anyone who ENJOYS crashing a motorbike at 240kph is an IDIOT anyway & I should ignore him! (It was a race track & a sort of controlled race crash but....)
post #4 of 29
I think any skier would have a tough time going much faster than 80k/hr wearing normal loose fitting and porous ski attire. I've been clocked at a little under 120km/hr on the fastest section of a closed icy downhill course while wearing a downhill suit. I think the GPS could be a little suspect. I can do 7 k/hr and loose/gain elevation standing still just due to buffered signals from the satellites on my GPS. I've never tried or thought of carrying it skiing though. I wonder how well it interpets the combo of elevation loss with movement on a lateral plane. World Cuppers are doing 80 km in GS while wearing downhill suits and again on a closed icy course. Those guys are hauling.
post #5 of 29
Q: How fast?
A: To be exact, too fast.

Q: How do you know?
A: The ski patrol and my wife told me so. Can't beat that for non-subjective measuring.
post #6 of 29
Thread Starter 
L7, nothing wrong with the GPS let me assure you. I have often checked it against other sources. More info check my profile. GS guys are pulling some pretty radical turns, while these other speeds were essentially straight lining in a tuck.

As for the combination of altitude loss and lateral position change, that's an interesting question, and one we also asked ourselves. I expect the machine isn't smart enough to calculate the path 3 dimensionally and merely compares its 2 dimensional position at the sampling rate of several times per second to calculate speed. If that’s the case then the actual speed would be faster. Some of these runs were on steep sections of downhill courses, anyone be able to guess the angle and do the maths? I doubt it would make a huge difference.

The point was not to dispute the validity of my friend’s speed, rather that of other posts I read. I seem to routinely read a post by Joe Blogs or Fred Nerk who claim that they routinely ski around resorts at 50 mph. Yet when I’ve actually measured these speeds ... on snow ... on skis, it’s clear that it really is hauling A much faster than I see other people ski. Hence my question whether people are actually going as fast as they feel they are.

Cheers,

Pete
post #7 of 29
Pete I max out on good terrain at about 80kph. How do I know. I just do.
post #8 of 29
Well I might hit 40 mph. That's a guess from being on motorcycles or water skis. Others have agreed to that number.
I think anything that has wheels gives a false sense of not going as fast. Until you hit something.
post #9 of 29
Do us a favor. "Calibrate" by setting your cruise control on your car. Do it on a straight section and then on a downhill grade. Assuming some speedometer error, and you can check this against mile markers (a minute per at 60 MPH), now adjust.

I think these GPS numbers are severely flawed. Vita-man is a balls to the wall kind of guy and only hit 74 in the traps during a speed event.

Assuming that you can do say, 40 mph in your car down a grade, engage the cruise and trigger the GPS. Do the numbers match?
post #10 of 29
The subjective answer is too fast, and I have 20+ stitches in my head to prove it right now. Note that it wasn't on the groomed, I am very careful when others are on the same slope (and yes, I can stop).

I did a few kilomètre lancé runs when I was a teenager, and went to 133 km/h. That was freaking fast for me at the time.

YA
post #11 of 29
Quote:
Originally posted by slider:
Well I might hit 40 mph. That's a guess from being on motorcycles or water skis. Others have agreed to that number.
I think anything that has wheels gives a false sense of not going as fast. Until you hit something.
I would agree my top speed these days is in the 40s. When I was younger and stronger I was meassured through traps in the 70s.

As for the wheels....I've topped 100kph desending on a road bike. Definately thrilling. The thought of hitting the ground and the resulting road rash at that speed certainly gets your attention...
post #12 of 29
I think that the GPS would be suspect due to the fact that commercial models have like +/- 25 ft. on position. Has something to do with terrorist types logging accurate locations for guided missiles and such. I could be wrong, if so please correct me.
post #13 of 29
Thread Starter 
Yuki, I have checked my GPS against multi-million dollar laser ring inertia navigation systems, airborne GPS, and ground-based calibrated flight management systems, and yes the numbers match to within 0.1 kph. That's close enough for me. My GPS is a small Garmin unit and both myself and my colleagues have been nothing short of astounded at how accurate this inexpensive unit is in operation. In addition, when static the GPS indeed reads zero with virtually no deviation in speed or position until the unit is moved, often as little as one step is enough to begin speed registration on the unit.

As an aside, virtually every car I've been in has a speedo that over-reads around 10%. Some people have suggested that manufacturers intentionally do this but I wouldn’t like to say. However the Pontiac Grand Am I rented in Canada was spot on, go figure.

If people choose to doubt the numbers, that’s fine. However once again, the point of the post was to ask how other people substantiate their claims of skiing around mountains at speeds that I now realise really are VERY fast.

Art, sorry we posted at the same time so I’ll edit. No the intentional inaccuracy was removed by the military a few years ago (at that time it was only accurate to within 100m), however since it's a military system they reserve the right to do what they like with the system. Inaccuracies are introduced over certain areas routinely when military operations are in process. Without going into technical details, the accuracy is determined by the number of satellites the unit can receive but won’t be better than around +/- 6-7 metres (mind you that’s pretty darn good). Incorporating a ground based transmitter of known location to correct atmospheric errors etc can get the system to within 30cm (now that’s mind blowing for us “in the trade”), but that’s a whole different can of worms nothing to do with this little portable unit. Speed is determined by comparing the unit’s position at the sampling rate of several times per second. Since the position will “dither” within its accuracy range, the speed will vary slightly depending on the position obtained, even when travelling at a constant speed. However in practice it seems the software is smart enough to smooth out these variations slightly and in use the speed variations are generally around +/- 1 kph at any point in time.

Cheers,

Pete

PS If anyone is interested in this GPS I can thoroughly recommend it. It is a Garmin eTrex http://www.garmin.com/products/etrex/ I purchased mine from Target in LA for US$125

[ February 17, 2003, 02:34 PM: Message edited by: Pete ]
post #14 of 29
Quote:
Originally posted by Pete:
Yuki, I have checked my GPS against multi-million dollar laser ring inertia navigation systems, airborne GPS, and ground-based calibrated flight management systems, and yes the numbers match to within 0.1 kph.
I have a Garmin etrex Summit GPS. Its maximum speed currently reads 44.2 mph, which agrees precisely with the computer on my bicycle. I know where and when I set that speed: the afternoon of last December 11th. Why do I know? Because about a half mile down the road from there, I took a slow left hairpin at about 15 mph, the front wheel washed out, and I broke my hip and femur. I'm resetting the display right now. I won't be going that fast for some time.

Except for very slow speeds, the GPS agrees with the bike computer exceptionally well. If only it's altimeter wouldn't drift so wildly.
post #15 of 29
Thread Starter 
Ouch!

Yes I believe the GPS system is less accurate in the vertical plane due to the geometry in how the units triangulate on the satellites.
post #16 of 29
Horizontal positions derived from handheld GPS units are fairly accurate-better than 5 meters under many conditions, especially if used in an area with WAAS (wide area augmentation system)(Most modern units are compatible with WAAS) Vertical Positions on the other hand typically can vary by as much as 10 to 30 meters.

The U.S. Government Recently turned off the system which previously deliberatly degraded the accuracy of the system (for non-DOD users), however there are still many potential sources of error.

If you're using the unit at a ski area, the most obvious source of potential error would be the unit tracking different satellites at the top of the run than it is tracking at the bottom of the run, due to said satellites being obscured by trees, mountains & etc.

If you are testing the unit aboard an airplane and extrapolating the results to ground use, I'd say it's apples to oranges, due to the fact that on an airplane you're probably consistantly tracking at least eight satellites, while on the ground you're possibly only tracking four or five satellites some of which get obscured by trees, terrain or the horizon as you move down the hill. The accuracy is largely dependent on the number of satellites tracked and their orientation relative to the user and to each other.

I'd guess the only accurate way to test speed is with a radar gun. They're available all over the internet

http://www.astroproducts.net/speedchek.htm

http://www.thetennisspot.net/

http://www.omnisportstech.com/cart.asp?category=12
post #17 of 29
Thread Starter 
Quote:
If you are testing the unit aboard an airplane and extrapolating the results to ground use, I'd say it's apples to oranges, due to the fact that on an airplane you're probably consistantly tracking at least eight satellites, while on the ground you're possibly only tracking four or five satellites some of which get obscured by trees, terrain or the horizon as you move down the hill.
No actually it was quite the opposite. The unit does not have the facility to use an external antenna and the windows on the flight deck are fitted with a thin metallic film within their laminations which shields the GPS signal. I had a difficult time obtaining enough satellites in the air on the hand-held unit. I’d argue that the only way to accurately determine speed is to travel a known distance within a known time.

Once again, this was not supposed to be an argument about the accuracies, or otherwise, of GPS. It appears as if there are those who have tested GPS units and found them remarkably accurate, and those who believe otherwise. Clearly nothing I can say will convince the latter group so let’s just leave it at that.

The purpose of the post was to enquire how people who claim to routinely motor about resorts at 40 or even 50 mph come to conclude this is their speed. Come on we’ve all read the posts, “… I normally ski at 40 mph and can tell you at these speeds the Mk III Widget Wonder ski is faaar superior to the X-49 Over-winder Series 5 ski, especially in the 184 length”. Great, but I think even the nah sayers will agree that it really takes some effort to get to 40 or 50 mph, so are you REALLY going as fast as you may think you are?

Cheers,

Pete

PS I respectfully direct any further discussions regarding GPS units to alt.gps
post #18 of 29
Hmmm, perhaps this is better suited here?

http://opentopic.groundspeak.com/0/O...3&f=5740990093

BobMc
post #19 of 29
Thread Starter 
Ha ha, indeed
post #20 of 29
I ski faster than all of you. How do I know? That's for me to know and for you to find out.

Sticks and stones may break my bones...

it's so fun to play with the insecure nursery school-minded "adults"

[img]graemlins/evilgrin.gif[/img]
post #21 of 29
Quote:
Originally posted by gonzostrike:
I ski faster than all of you.
No you don't, cause during the Academy and the Gathering, you never skied past me once, so you must be slower than me.

S

Oh yes, after all your talk about going, you were a no-show. Maybe that's why you couldn't ski past me in Utah.
post #22 of 29
Quote:
Originally posted by Wear the fox hat:
</font><blockquote>quote:</font><hr />Originally posted by gonzostrike:
I ski faster than all of you.
No you don't, cause during the Academy and the Gathering, you never skied past me once, so you must be slower than me.

S

Oh yes, after all your talk about going, you were a no-show. Maybe that's why you couldn't ski past me in Utah.
</font>[/quote]I don't know about you, but my relatively low income (compared to oboe et al) means that all future plans are subject to last minute change.

since you seem to have been absent for my explanations, I will tell you this: (1) work got incredibly busy immediately before and during the Academy/Gathering timeframe; (2) I don't have anyone to whom I may delegate my work; (3) my truck needs new brakes and I didn't have the $$ to get them, and wasn't about to drive 8 hrs down, repeatedly around SLC, and then 8 hrs back on dodgy brakes; (4) I have been focusing more on my mtb riding this year. Combine these factors and you get a no-show.

Maybe I should have prefaced all my promises to attend by saying I'm not perfect and not a saint. Would that have appeased your desires?

I really don't understand why all the hubbub about my no-show. How many other Bears didn't show? Hmmmm?

I guess I'm supposed to take the cynical view that negative press still is press and therefore is good for me.

:
post #23 of 29
Quote:
Originally posted by Pete:
L7, nothing wrong with the GPS let me assure you. I have often checked it against other sources. More info check my profile. GS guys are pulling some pretty radical turns, while these other speeds were essentially straight lining in a tuck.

Pete
I wasn't meaning to dispute your friends speed only to say it is hard to get over 80 km due to aerodynamics and other factors but not impossible. I have dead ass straight tucked the longest steepest portion of our world cup downhill course where they set 3 big turns normally. I'm sure I broke 80 (maybe 100) even in my loose porous parka. I would hardly qualify that as 'skiing around a resort' though. I could see the whole pitch and NO ONE was on it. It was groomed baby ass smooth and I skied it several times that day already. Not to mention a warm day with just a slight soft layer on top of the snow pack. Day to day skiing? Not really.

I ski at a local hill which is very quiet mid week in the morning and always groomed to perfection. The pitches are wide open and steep and have very few blind drops giving a great view going in to an empty slope. I will ski very fast there and get into the 80 km zone I'm quite sure. I still don't qualify that as 'skiing around a resort'. If I want to ski fast and the public starts flowing in meaning I can't hit the pitches without others being in front of me I go home. Not really normal resort conditions. On a slope with others skiing doing 70 km is courting disaster and you'd best have lots of room to take a line far from other skiers because that's fast enough to bring some real unpredictable encounters with others.

As for the GPS, as a pilot you're clearly familiar with their use and accuracy. Up high you will always have the satellites low in the horizon to give the vectors for accurate measurement. But I find in the mountains it's hard to always get that critical low in the horizon satellite that will give you accurate elevation. Ideally I think you'd need one low at 90 degrees to your travel as well as 3 or 4 more dispersed in the sky for real accurate readings. The mountains usually block that optimum configuration where I am. Differential GPS would fix that if you had one that could receive the radio signal from a fixed unit. Some years ago I did some seismic surveying using differential GPS and it was pretty amazing accuracy you could get once the data was downloaded and processed. I also ski in Canada and your military doesn't yet see us as enough of a threat to have a full web of the satellites over our northern latitudes.

Suunto is coming out with a new GPS watch. It will be fully downloadable to record a days activities. You sound like a gadget guy I'm guessing you'd find that a fun toy. As a pilot you might even be able to afford it and sort of justify it.

The comment about wife and patrol telling you it's too fast, it's hard to argue that. As for the stitches, I think you want to figure out too fast just a hair before that speed.
post #24 of 29
Thread Starter 
L7, I refer to my comments above re GPS comments. Please don’t take this personally, however, while I’m all for theory and speculation, sometimes there is no substitute for empirical observation. Your hypotheses regarding GPS use may be logical but sadly not accurate in practice. The GPS’ onboard accuracy calculation typically hovered around 7m and I never saw it go above 15m in use. If anyone wishes to argue the GPS accuracy matter further please go out, buy a unit, and try for yourselves rather than wildly speculating about what “should” happen!

Phew, I feel better now

L7 you did however get to the crux of my post regarding speeds, when you said “I'm sure I broke 80 (maybe 100) ...” (possibly on the same courses he used by the way). Firstly how did you know this was how fast you were going? Secondly I think we agree that these are not typical skiing situations. Yet I read time and time again on this board people claiming that they “routinely” ski at these speeds. Considering above I would have to consider the claims rather dubious indeed!

Cheers,

Pete

PS It’s not “my” military, I am Australian!
post #25 of 29
Quote:
Originally posted by Pete:
L7, I refer to my comments above re GPS comments. Please don’t take this personally, however, while I’m all for theory and speculation, sometimes there is no substitute for empirical observation. Your hypotheses regarding GPS use may be logical but sadly not accurate in practice. The GPS’ onboard accuracy calculation typically hovered around 7m and I never saw it go above 15m in use. If anyone wishes to argue the GPS accuracy matter further please go out, buy a unit, and try for yourselves rather than wildly speculating about what “should” happen!

Phew, I feel better now

Did not mean to give the impression I was wildly speculating about what 'should' happen. I meant to relate my experiences with my own hand held Garmin 12. I have also used it in commercial aircraft in pre 9/11 days. I use it in the mountains where I live and coastal waters while sea kayaking. I have also used it in the very high arctic where a compass is rendered marginal. In broad horizon situations (ocean, tundra, 30,000 feet) the triangulation and accuracy is much improved, in closed in mountains it can be fair to marginal depending on satellite deployment. The deployment of satellites seems to vary quite a bit with latitude and I expect military strategic importance. I have no experience with a professional aviation unit. I prefer to not take any comments personal but that is hard when the comments begin with my name. I enter this debate because I find it mildly interesting but not to make myself feel better. To each their own.

As to how do I know my speed. In my initial post here I mention being clocked at a little under 120km. That was in a downhill race and clocked by courtesy of the local enforcement and radar gun. I have been clocked on radar in a few different races. Saying I approached 100 is some what of a guesstimate but it was on the same run the radar gun was used so that helps. I think it is a judgement of how fast things are coming at you and the feel of your skis not to mention wind pressure and to a lesser degree wind noise. I downplay wind noise because when I was under radar I was wearing a downhill suit and full helmet. When you loose the flapping clothes and wind in ears you have to rely on other references. I think a lot of people wearing full helmets for the first time loose a lot of this reference of wind noise and find themselves going faster than they mean to until they adjust. Partially for that reason I bought a helmet with removeable earflaps.

By entering this debate of speed or GPS I really am not trying denigrate your knowledge of either topic, just offering my experiences to the debate from which I may learn and someone may learn from some of my experience. As I mentioned in my earlier post I haven't taken my GPS skiing. However I find here the satellite coverage tends to be better on the southern horizon and that narrows my choice of runs. Not sure if I'm willing to give that much over to the experiment.
post #26 of 29
Sorry about the government thing. I saw on your profile that you fly for Air New Zealand I think. I forgot, tend to assume most on here are from the States.
post #27 of 29
Thread Starter 
Air New Zealnd? Ooooh so close but no cigar
post #28 of 29
QUeensland And Northern Territories?

S
post #29 of 29
how to measure one´s speed ?

simple: go to st. anton and go down the speed course with automatic speed measuring.

now, who knows how exact that thing is.....

i was clocked 90 km/hr, but that´s like 5 years ago and didn´t feel too fast....
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