
Are Kilian Jornet's Speed Records Too Good to Be True? - gpresot
https://www.outsideonline.com/2324076/ultrarunner-kilian-jornet-everest-controversy
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runnr_az
No. (At least to anyone who's followed his career.) That dude is a total class
act.

As a side note, the article mentions a Seb Montaz-Rosset film that features
Kilian called "Downside Up." It's... maybe one of the craziest things I've
ever seen. Ski mountaineering is amazing!
[https://vimeo.com/ondemand/downsideup](https://vimeo.com/ondemand/downsideup)

~~~
DrBazza
Betteridge's Law of headlines.

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chair6
The dude is a freakin' machine. There's a short film (13 mins) called 'Kilian'
at
[https://www.youtube.com/watch?v=7eVBrMcflDE](https://www.youtube.com/watch?v=7eVBrMcflDE)
which made it into the Banff Film Festival last year. Worth a watch if you
want get a better feel for how he travels and his thought process. Food for
twenty hours in the mountains? Oh, I'll probably take 4 Snickers or
something...

~~~
zwp
Nice, thanks.

What are those cute little axes that he's running? And what's going on with
them at 10m50 - is that a foldout pinky rest?

[https://www.youtube.com/watch?v=7eVBrMcflDE&t=650](https://www.youtube.com/watch?v=7eVBrMcflDE&t=650)

~~~
aplusbi
Looks like a pair of Petzl gully axes.

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buzzdenver
This is Outside magazine stirring the pot for no good reason. Kilian has
proven dozens of times in highly competitive and controlled races that he is a
notch above competitors from his generation. Also, the FKT-s he sets are not
out of this world, and many of them have been broken since (Kilimanjaro and
Aconcagua iirc). Anyone who has used a watch GPS enough times will know that
once in a while they will just misbehave and report incorrect coordinates.

~~~
h2j24
I think the article largely paints a favorable picture of Kilian.

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bosdev
I really don't get why he doesn't just carry a reliable GPS tracker with him.
Seems so much easier than arguing with people online.

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aplusbi
He's probably using a GPS watch which is very convenient but error prone.
They'll frequently get misreads (where they briefly think you are miles away
from where you actually are) and accumulate small amounts of error over time
(the granularity isn't great, so sometimes it will continue to increment
distance even if you are standing still).

Really reliable GPS trackers are big and heavy, and for someone attempting
speed records just not worth the weight. And even with reliable GPS tracker
there will still be doubters who will claim the data was faked.

~~~
logicallee
How does error-prone GPS work on a technical level? Based on a description of
GPS I would think it's kind of an "all or nothing" thing (no signal, or exact
calculated position)

[https://en.wikipedia.org/wiki/Global_Positioning_System](https://en.wikipedia.org/wiki/Global_Positioning_System)

I just don't get how you can get "low-fi GPS". What happens exactly? Either
you receive the signal or you don't, and any bounces off the ground or
something will just add a couple of meters.

~~~
jrockway
[https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_...](https://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System)

The largest source of error is ionospheric delay which changes throughout the
day. This can be corrected with additional ground measurements (DGPS, WAAS) or
a second receiver on a different frequency. GPS watches do WAAS but nothing
else.

(As an aside, I have been unable to get my hands on any modern multi-frequency
GPS receivers. If someone has a link to one that I can buy with a credit card,
I would love it! But that rules out the industrial ones that are "call for a
quote" because if you have to ask, you can't afford it ;)

Other sources of error are inconveniently positioned satellites ("dilution of
precision"), multipath reception, and the intrinsic quantized nature of the
code being transmitted by the satellite. (This last one can be mitigated by
tracking the phase of the carrier signal independently from the navigation
code, however. Not sure if GPS watches do this or not, but I suspect they do.
A comment below implies they don't have the power budget for the extra CPU
cycles, though, which might be true.)

An ideal model of GPS makes it seem like there are four unknowns, but in
reality there are many more unknowns. You don't know exactly where the
satellites are (ephemeris errors). You don't know if the clock on the GPS
satellite is right. You don't know the speed of light through the atmosphere
on the exact path between you and the satellite. You don't know the exact time
at the receiver's location (internal oscillator error, etc.). You don't know
that the signal from the satellite took a straight line route. You don't
necessarily have an optimal view of the sky to be able to hedge against the
other errors (HDOP/VDOP/TDOP). As a result, you don't get a pinpoint location
in the real world.

(One last thing, it turns out there is a reason why GPS receivers give you
separate speed and position outputs. Speed can be determined independently
from position by monitoring the doppler shifts on the received signals. Many
receivers do this, which is why your speed can be correct but your position
wrong.)

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mojoB
> As an aside, I have been unable to get my hands on any modern multi-
> frequency GPS receivers. If someone has a link to one that I can buy with a
> credit card, I would love it!

Try SwiftNav or Tersus. I have not used either of them so I can't comment on
the quality, but $1-2k for an RTK setup is pretty great. They are both more
'startup' than traditional suppliers.

uBlox F9 looks good but isn't quite available yet. They have a solid line of
single frequency receivers so I'm looking forward to seeing pricing.

I have briefly tested some Unicorecomm from China, and they work well, but
they miss your online store requirement, and the documentation is nonexistent.

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dnhz
Going up to those altitudes without supplemental oxygen sounds absolutely
insane to me. Studies via MRI have shown brain damage even in climbers
climbing Mont Blanc (4,808.7 m (15,777 ft)).

[https://www.scientificamerican.com/article/brain-cells-
into-...](https://www.scientificamerican.com/article/brain-cells-into-thin-
air/)

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24gttghh
I don't understand the desire to race as fast as possible through the natural
splendor of the mountains. I feel like these speed-climbing folks are really
missing out on the experience.

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EliRivers
For some of these people, the fact that there's natural splendour there isn't
the point and isn't relevant. It's like game-grinding. Pick a new achievement
- running through mountain trail X - and then grind it. Tick it off, do the
next one. Whatever they're seeking is inside their heads and the setting is
just a convenience. It could just as easily be a featureless 50 mile tunnel.
The setting is relevant only as far as it's a recognised thing to grind and
tick off.

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adenadel
This is not at all how professional trail/ultra runners approach their lives.
You can follow a lot of them on social media (including Kilian Jornet) see how
they actually spend their days.

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EliRivers
And it's not how everyone who plays games plays. But some do. I suspect there
are many you don't see on the social media. It would be a strange field of
human endeavor if it somehow managed to not have any people like this. I doubt
they'd be the professionals. They wouldn't be the social media self-
publicitors.

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adenadel
The professional ultra running scene isn't like what you think of when you
think professional sports. There are certainly runners on the track and in
road races that take the mindset you are describing, but ultra/trail running
is very different from other pro sports.

~~~
runnr_az
That's been my experience too... I've known many triathletes who will do an
extra lap around the parking lot to meet their coach's exact plans, but that
seems a lot less common among trail runners.

