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GPS and the Truth
Last Post 07/09/2019 07:35 AM by Hot Habanero. 4 Replies.
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79pmooney

Posts:2154

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06/10/2019 06:13 PM
I got an ELEMNT BOLT GPS unit for OTGG to better the odds when I get left behind and come to a fork.  Went for my first ride with it yesterday.  102.6 miles.  Sounds about right.  The portions I have measured off my Thomas guide checked very closely.

But!!!! Altitudes and elevation climbed.  I rode a basically flat route out to a reservoir in the foothills, around, then basically flat with several 1-200' hills and some rollers, then a 1100' climb over the Chehalems (with an elevation sign at the county line/divide).

I was well over 1000' of climbing before I even got to the reservoir.  Approaching 4000 before I started the final climb.  5400' for the day!  (My tabulations would have been flat to the lake, 700' around, say 400 to the base of the climb, 1100, then downhill and flat so 2200'.)

And the altitudes - at first I believed them and found it interesting to learn the elevations on known points.  Then I started noticing odd discrepancies.  OK, not perfect.  Over the final climb I did not watch the progress but looked when I passed the sign.  1006'!  I'm betting the county surveyors were in to within oh, say 20'.  If that is the case, my GPS missed by around 266'  More than the elevation of my house above sea level.

I am now quite aware that many of the numerous digits on this device are insignificant, including more than a few to the left of the decimal.  And that ride total "elevation gained"?  BS with capital letters.  My ability to be impressed with others' claims to massive amounts of climbing just took a big hit.

Ben
Orange Crush

Posts:2564

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06/10/2019 08:00 PM
Does this device track elevation from air pressure? If so is it calibrated properly?

The rides I see from friends who have this thing don't seem to be off by a factor two in elevation. Maybe just some fiddling.

I'll slot in behind you to find my way next week. Other than that I am banking on course indeed being well marked. Crews hard at work on cleaning up stage 1 today. Landslide removal snow removal fixed up a washout from photos posted on fb.
longslowdistance

Posts:1839

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06/10/2019 10:53 PM
I was afraid this was going to be a flat earth thread.
Orange Crush

Posts:2564

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06/10/2019 11:25 PM
A ton of people seem to have elevation issue. For some its skewed way down. https://support.wahoofitness.com/hc/en-us/articles/115000441324-Why-am-I-Seeing-Elevation-Differences-in-My-Ride-Data-
Habanero

Posts:165

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07/09/2019 07:35 AM
Ben, I’ve noticed the same thing with my ELEMNT. I’ve contacted their technical support and they said they’d look into it and I’ve never heard back. I was not impressed at all and it makes me wonder what other metrics are off.
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