Forums >Gears and Wears>"In GPS We Trust"
I've got a fever...
A good illustration of GPS error with regards to elevation: Bonkin lying on his couch:
While not as fancy as jog-mowing, my couch does has some serious hills. Here's a HR chart of me laying on the couch when my Garmin was still a shiny new toy.
Now granted, elevation error on a Garmin is worse than positional, but it gives you a good idea that these devices are far from perfect.
On your deathbed, you won't wish that you'd spent more time at the office. But you will wish that you'd spent more time running. Because if you had, you wouldn't be on your deathbed.
Menace to Sobriety
That's true, but in practice the gps is not accurate (or at least, not reliably accurate). If you have access to a running track try running the 100m straight a few times and see what distance the gps gives you. In general it'll be different each time and may well be a few % out.
Oh, I know how erratic GPSs are. I've been using them in some form for over twenty years. They're way better then they used to be, but still far from accurate. I've done the track experiment as well. What baffles me is when for 5-6 laps you get a consistant offset of ~.01 mile/lap, then all of the sudden you get one thats off .07 or something. No lane changes, clear view of the sky.....
Janie, today I quit my job. And then I told my boss to go f*** himself, and then I blackmailed him for almost sixty thousand dollars. Pass the asparagus.
Lazy idiot
But if you're trying to run a particular time/pace in a race then you should be careful about relying on your gps for pacing information. Getting 35km into a marathon and then realising you've averaged 5 seconds per km slower than you thought could well be a problem.
It's a problem only if one actually "could" run 5 seconds per mile faster.
And if one could, the GPS-during-a-race-pessimist in me would wonder why one did not.
I use my GPS watch in races, but really only to record what happened to look at later. I run by feel. Do I look at my watch during the run to view pace info? Yes. But I've proven in the past that I'll continue to run too fast until I crash, even when the Garmin is telling me I'm running too fast. That's how I know I'm an idiot not reliant on the Garmin for adjusting pace in a race.
Tick tock
To add to what Drew is saying, I sometimes try to run harder when my GPS says I am slacking and it does not work, maybe I'll pick it up for a couple of minutes and then back to what I am capable of running that day.
Maybe one day I'll learn to pace evenly, until then the GPS is for post race talking points, yeah that hill killed me etc (never mind the fact that I did not train for the expected hills)
Best Present Ever
Were you using instantaneous pace? Because even a perfectly good GPS will be useless for displaying that. The best you can do is lap pace. If you want a laugh, set it to display altitude or %grade and watch it go crazy.
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It's a problem only if one actually "could" run 5 seconds per mile faster. And if one could, the GPS-during-a-race-pessimist in me would wonder why one did not. ...
...
If you're running the first half of your marathon so fast that you couldn't run 5 sec/mile faster, you're probably in for an exciting second half.
It's a 5k. It hurt like hell...then I tried to pick it up. The end.
If you're basing your marathon pace off of half marathon PR pace, you're probably right.
not bad for mile 25
Anybody who is pacing by Garmin expecting it to measure distance precisely just doesn't get it. BUT. Garmins are still incredibly useful for pacing in a race. Just use average lap pace to keep at about the pace you want for this mile/km, check your actual splits each mile, and adjust. Because the Garmin will tend to measure a bit long, you want the Garmin average lap readout to be a few seconds faster than your goal this lap. And be sure to turn off autolap! The real problem here is not in mismeasured courses, but in badly misplaced mile/km markers, which is much more common. Unless you know they are accurately placed, then you can't reliably use the above method, and you have to go by Garmin the whole way, pacing faster than your goal to compensate for your guessed Garmin excess (~ 1%). When you're not sure about the mile markers is the worst. Do I trust that the markers will even out? Or is tracking them just going to cause me lots of angst? Couple months ago I ran a half where I took the mile markers as ground truth. I should have been suspicious; every one was bang on my Garmin's measurement, so at M12 I was at 12.01. The finish line was at 13.2+, so I was ~40 seconds over my goal. Yeah, I was annoyed.
Anybody who is pacing by Garmin expecting it to measure distance precisely just doesn't get it.
BUT. Garmins are still incredibly useful for pacing in a race. Just use average lap pace to keep at about the pace you want for this mile/km, check your actual splits each mile, and adjust. Because the Garmin will tend to measure a bit long, you want the Garmin average lap readout to be a few seconds faster than your goal this lap. And be sure to turn off autolap!
The real problem here is not in mismeasured courses, but in badly misplaced mile/km markers, which is much more common. Unless you know they are accurately placed, then you can't reliably use the above method, and you have to go by Garmin the whole way, pacing faster than your goal to compensate for your guessed Garmin excess (~ 1%). When you're not sure about the mile markers is the worst. Do I trust that the markers will even out? Or is tracking them just going to cause me lots of angst?
Couple months ago I ran a half where I took the mile markers as ground truth. I should have been suspicious; every one was bang on my Garmin's measurement, so at M12 I was at 12.01. The finish line was at 13.2+, so I was ~40 seconds over my goal. Yeah, I was annoyed.
Sue.
There's a Fox News joke somewhere in there.
Okay, #4, but the dots should be situated on the far right.
My first race, a 10k. I thought the sign indicating "5" meant that I was halfway along. HA.
"If you have the fire, run..." -John Climacus
It's a problem only if one actually "could" run 5 seconds per mile faster. And if one could, the GPS-during-a-race-pessimist in me would wonder why one did not. ....
....
Actually, even in a 5K, I could easily run my first mile 5sec per mile faster. If I ran even the first mile of a 5K so fast I couldn't pick it up by 5sec/mile, I'd be in for a crash.
Seems like a kinda... questionable? ...race plan, to run so fast you couldn't pick it up another 5sec/mile if you wanted to.
Runners run
Good Bad & The Monkey
Drew's point was that if you adhere too strictly to a predetermined pace plan, you might prevent a breakthrough.
Sometimes that is okay.
I'm running somewhere tomorrow. It's going to be beautiful. I can't wait.
Poor baby
Prince of Fatness
Running is stupid.
Not at it at all.