GPS Accuracy
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I have a friend who obsesses over every .1 difference between his Garmin readout and the distance a race is supposed to be (he is still complaining about a half marathon 6 months ago that Garmin had at 13.25). I will tell you the same thing I tell him: "Garmin lies, the important thing is that it lie consistently"
As Carson already pointed out Garmin is generally considered the most accurate method unless you plan on running with a measuring wheel.
At least everyone had to run the same extra distance between start and finish.
Not necessarily. If I run the inside tangent of every corner and you run the outside, you will have run further than me.
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Typically I wear my Bluetooth HRM that syncs with my phone because it's nice to have a log of this stuff from training but this weekend during this half I'm using my Polar FT7 for a HRM to decouple that from the phone. My main reason is that I don't totally trust the phone to give me an accurate measurement for my pace and I've had the rare occasional time when it was totally way off by as much as a mile.
When I can afford it I'm getting a Garmin. For now however the phone app is a good tool and it's been pretty accurate on the distance and pace on races I've done but I don't trust it 100%. If the phone reboots or dies I can do the race just fine with nothing but a measurement of my HRM to tell me what my pace is. I have a good idea of what speed I'm running based on my pulse.
Phone GPS is accurate for the most part but don't trust it to tell you the exact distance and time.0 -
I have a friend who obsesses over every .1 difference between his Garmin readout and the distance a race is supposed to be (he is still complaining about a half marathon 6 months ago that Garmin had at 13.25). I will tell you the same thing I tell him: "Garmin lies, the important thing is that it lie consistently"
As Carson already pointed out Garmin is generally considered the most accurate method unless you plan on running with a measuring wheel.
At least everyone had to run the same extra distance between start and finish.
Not necessarily. If I run the inside tangent of every corner and you run the outside, you will have run further than me.
Considering I stagger like a drunken sailor on three-day liberty long about mile 10, I probably have covered considerably more distance. At least the opportunity for equality exists in theory
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I discussed course marking with the pacer at one of my recent marathons and he explained that if he runs a course and comes up with 26.2 he assumes it was short. The methods they use to certify the course forces them to be long when you run them and that 26.35 is about where he expects his Garmin to be for a certified marathon.Also, with a certified course measurement, they build in a margin of error by adding a bit to each mile to make sure that it is definitely not under and they also measure the shortest possible distance one could possibly take around the course. So, you should never have a HM come up as exactly 13.1 if it was certified. The measurement process is details on the USATF website.0 -
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I know sometimes (few occasions), my Motorola watch outright lied on a training run. Once it told me that I did 3 miles in 18 minutes (going for another 7 miles after that)... I knew this was a lie since I probably was 2.5 miles away from where I started. It also lies when there is a lot of cloud cover and foliage cover (lies the reverse, 15 minutes to do a mile) and I've noticed this with the garmin as well. I remember I was running an extra 8 miles sometime last year on the weekend since I was doing an unpaved trail with a lot of foliage cover. I was always tired and my husband pointed out to me that I was actually doing 8 more miles than I thought I was doing based on the distance I started and ended.
However, for the most part when I do enter races, the GPS is acurate with the chip time and the distance on the GPS is usually further than the race distance.0 -
great article!
this, from the article, is all you need to know: "Your GPS is a great tool for workouts, for figuring out approximately where you are in a race and for elevation and pacing charts."
The key word being "approximately"!0 -
LOL. I've had better. I've had Runkeeper tell me I did over 100 km on a run that was actually 10. You should have seen my speeds. LOL.
But if you keep it on your runkeeper account (without deleting the extra waypoints) then it will mess up your records/achievements, so when you really do break a speed or distance record, you don't get notified.Runkeeper once told me I covered 14 miles (I ran 4.3) at an astounding average pace of 4:10, I even ran a few sub 2:00 miles. I was highly impressed since I usually run 11-12 min miles. Then I saw the map. It showed I was leaping people's homes in a single bound, running across major highways (several times), I even ran through the high school and across a couple bodies of water. It was an impressive route and an Olympic caliber run. I keep that in my runkeeper just so I can remember what I can really do if I work hard enough.
My Garmin shows that I travel about 1 mile an hour while it's sitting in a window. GPS is not perfect. Certified race course is what counts.0 -
I discussed course marking with the pacer at one of my recent marathons and he explained that if he runs a course and comes up with 26.2 he assumes it was short. The methods they use to certify the course forces them to be long when you run them and that 26.35 is about where he expects his Garmin to be for a certified marathon.Also, with a certified course measurement, they build in a margin of error by adding a bit to each mile to make sure that it is definitely not under and they also measure the shortest possible distance one could possibly take around the course. So, you should never have a HM come up as exactly 13.1 if it was certified. The measurement process is details on the USATF website.
This is good to know. Thank you for posting!0
