According to my garmin, the bike course had 6,862 feet in total climbing…is this about what everyone else had? I’m just wondering because it also had the run course with 6591 feet of total climbing and I know that’s a mistake.
I heard 5500.
Got 5800 climbing. also had around 5800 in 2007.
My Suunto came in around 4500. It doesnt use GPS, it uses barometric pressure. On Mapmyride.com it shows 2700.
I had 3700ft of total ascent on my polar PM, which uses barometric I think, run course I had about 170ft of climbing.
MC
My Garmin Edge recorded 6058 feet of climbing and 5845 of descending.
Not sure how that works?? If I ended up where I started, shouldn’t they be equal?
It SHOULD be, but it’s usually at least a little off. My garmin 705 always seems to be within 2 or three feet when measuring climbing and desending (when I start and finish at the same place), but I was curious to see what everyone else got. I thought almost 7,000 feet seemed a little much…
My garmin 305 registered an implausible 8000 ft climbing and 7990 descending. This seemed way high to me, but my Garmin was dead on for distance and speed. I’m mystified how it can be off by so much when it comes to elevation.
No way is near 7000 ft, I would go with MapmyRide, 2700 ft seems more plausible.
2700? For one loop maybe…
Maybe it measured 3 feet every time you collapsed and then got back on your feet?
LOL, :))
MapMyRide is HORRIBLE to use for elevation gain. I have looked up numerous rides around my area and compared it to my dat, other riders data, and written data. Usually, MapMyRide underestimates by at least 50%.
As for the IM/Louisville bike course, I measured 5200 ft elevation gain with my Garmin. Of the two other times I have ridden the course, this is exactly what I got each time. I was using a different Garmin each time.
I’ve seen reports from 5000 to over 8000 (a few, not just one). I figure it must be somewhere in between. Where can one find an “official” measurement of elevation data for the course?
Maybe you are confusing precision with accuracy?
Two training partners and I ran a 5 mile track workout at the local highschool with our newly purchased Garmin Forerunner 305 devices and all three of us got elevation gain/loss numbers in the hundreds of feet, and relatively similiar to each other. Common sense, running feel, and our eyes tended to suggest that the track was rather level.
There is plenty of information on the web about the use of GPS technology as an altimeter and the algorithms being used to smooth the data.
The Louisville course is just not all that hilly despite what our Garmins (and bike times) might suggest!
I have another theory. Tell me how this one sounds. When I have my Garmin 305 mounted to my road bike, it’s elevation tends to be pretty accurate (or at least correspond well with other data points). But in tri’s, I wear it on my wrist, therefore the constant (though small) movements of my hand/arm accumulates to create big elevation numbers. It also accounts for why running on a track would give big numbers: your arms is constantly swinging (to the tune of ± 5cm/stride x 1600strides/mile = 80m/mile ~= 250 ft/mile (excuse these rough estimates and conversions and mixed units)).
This theory is predicated on the fact that an instrument that is remarkably accurate over horizontal distance (mileage) can’t possibly be so wildly off on vertical distance…after all, the position is triangulated (ok, I have no idea the real technical method, but triangulation seems like a reasonable simplification) based on the difference in positions on an x & y axis between various satellites, right? So vertical and horizontal would be hard to tease apart, wouldn’t they?
Ok, I admit that this theory might be totally wrong and i’m not doing all the necessary google searches to test it, but do others see a big difference in accuracy between when the unit is mounted on your bike and when it’s on your arm?
“This theory is predicated on the fact that an instrument that is remarkably accurate over horizontal distance (mileage) can’t possibly be so wildly off on vertical distance…after all, the position is triangulated (ok, I have no idea the real technical method, but triangulation seems like a reasonable simplification) based on the difference in positions on an x & y axis between various satellites, right? So vertical and horizontal would be hard to tease apart, wouldn’t they?”
Questions for you. If you were to discover that your particular Garmin was accurate to within, say, 30 ft for any single reading and that error could occur in any plane, vertical, horizontal, whatever. Can you see how an algorithm written to smooth/“correct” for this error might be easier to write for the horizontal plane? Couldn’t you make certain reasonable assumptions about horizontal directional changes for a runner that you would not also apply to the vertical plane? How does real world speed change when directional changes are limited to the horizontal plane? What about the same for the vertical plane? What about bike -vs- run?
There ARE differences and these must be accounted for in any algorithm used to smooth/“correct” data for a device with the level of error the technology experiences.
Make sense?
The difference in the smoothing algorithm for the horizontal and vertical plane makes a lot of sense to me. Thanks.
It still puzzles me when, especially on long rides with a lot of climbing, there’s a great deal of agreement between different measurements (e.g., I did the Mountain Mama century last month in Virginia and the advertised elevation change matched the my Garmin data within a few hundred feet (out of ~12,000)–maybe they used a Garmin to measure it, but I suspect they originally used USGS data to calculate by hand and perhaps made subsequent revisions as technologies became available in the last decade). My only theory about this had to do with the relative stability of the unit when mounted on my bars vs. the many movements on many axes that occur when it’s on my wrist.
As a side note, Greg’n, the civility and clarity with which you helped me understand this are appreciated 
Civility will abate once I accumulate the requisite number of posts on Slowtwitch. I do, after all, want to fit in!