Best method/device for measuring elevation gain riding

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Best method/device for measuring elevation gain riding

Postby 300hp » June 4th, 2013, 11:41 am

So,
Yesterday I realized that my Garmin was providing an estimate based off of USGS maps as to feet climbed over the course of a ride. It's estimate was very, very low. What pricepoint GPS, or other devices, are better at this?

Is there a better program I can run my recorded track through to give me better data?

thanks!
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Re: Best method/device for measuring elevation gain riding

Postby utabintarbo » June 4th, 2013, 11:47 am

Which Garmin product are you using now?
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Re: Best method/device for measuring elevation gain riding

Postby 300hp » June 4th, 2013, 11:49 am

I have a forerunner 205 watch. Original (blue bulky thing) model. It's very rudimentary, but I bought it at the REI garage sale 3 years ago just for an extra charger for my partner's GPS. Now her watch is dead, and after a quick software re-install, mine is still going strong :)
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Re: Best method/device for measuring elevation gain riding

Postby Chippewa93 » June 4th, 2013, 11:51 am

Garmin 800 it's awesome. Combined with the Connect website there are some great training tools. I use the virtual partner a lot too
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Re: Best method/device for measuring elevation gain riding

Postby c0nsumer » June 4th, 2013, 12:18 pm

An easier way to think of this is the methods by which you have to calculate elevation gain. The first is GPS, which has an altitude accuracy of (if I'm remembering correctly) of ~30' at best. The next is barometric, which gets weird on long rides as the pressure outside typically changes. Then after that most GPS units will do some sort of autocorrection based on both of those, particularly if you put in markers that list a certain lat/long as a given elevation it can autocorrect against. On top of that, many pieces of software (eg: the Garmin site) will do elevation stuff based on topo data they have, which may or may not take into account what your GPS unit recorded.

Coupled with all of this is the problems brought about what is known as the coastline paradox. Applied to elevation, it is correct to say that any distance can have an infinite elevation based on the minimum measurement. With a minimum measurement of ~30' for GPS alone, it's not possible to measure elevation in steps of less than 30' (or whatever your minimum accuracy is) using GPS. The things mentioned in the previous paragraph can help improve this accuracy.

That said, there's another problem in measuring elevation that comes up. Say you have a series of 10 rollers each 5' in height on an otherwise level piece of ground. Is that 50' of climbing? Since it's within the minimum measurable by your GPS it'll be recorded as flat ground. Or say you are in heavy tree cover where your accuracy is degraded to 100' or 200' and you are climbing 75' up and down a ridge... you'd definitely want that counted, but it may not be.

I've found that there's no easy answer for this, which is why there are so many wildly varying elevation counts for the same route. One person may get 10k' for something while another may get 6500'. What I do is just use my Garmin Edge 500 at its defaults, and take whatever it gives me as a fairly good estimate. Garmin has loads of highly qualified data folks working for them, so I figure they've come to a sane base solution. It's still skewed by atmospheric pressure changes (look here and here for longer rides where I did laps which trend over time), but I think it's probably a good enough estimate.
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Re: Best method/device for measuring elevation gain riding

Postby Paul Brown » June 4th, 2013, 12:24 pm

My method: If I am tired after a ride where there is elevation I climbed a bunch, and if my legs still feel fresh when I am done I didn't climb much. A teckno gadget rider I'm not :P .
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Re: Best method/device for measuring elevation gain riding

Postby iamkickstand » June 4th, 2013, 5:14 pm

as consumer pointed out, measuring elevation gain and loss over a mountain bike ride on our tight and twisty crammed into a shoe box trails is a big guess at best.

Over a long road ride your garmin should be accurate enoguh for argument sake.
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Re: Best method/device for measuring elevation gain riding

Postby rvd » June 4th, 2013, 8:42 pm

c0nsumer wrote:What I do is just use my Garmin Edge 500 at its defaults, and take whatever it gives me as a fairly good estimate. Garmin has loads of highly qualified data folks working for them, so I figure they've come to a sane base solution. It's still skewed by atmospheric pressure changes (look here and here for longer rides where I did laps which trend over time), but I think it's probably a good enough estimate.

Very cool. The elevation change with time is about 10ft/hr for both rides (interestingly, or coincidentally, elevation went up / barometric pressure down in both cases), which produces an *extra* gain that is negligible compared with the actual climbing. Of course that leaves other errors (trees, coastline effect, etc), but temporal drift is clearly a minor effect.
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Re: Best method/device for measuring elevation gain riding

Postby c0nsumer » June 4th, 2013, 9:20 pm

rvd wrote:
c0nsumer wrote:What I do is just use my Garmin Edge 500 at its defaults, and take whatever it gives me as a fairly good estimate. Garmin has loads of highly qualified data folks working for them, so I figure they've come to a sane base solution. It's still skewed by atmospheric pressure changes (look here and here for longer rides where I did laps which trend over time), but I think it's probably a good enough estimate.

Very cool. The elevation change with time is about 10ft/hr for both rides (interestingly, or coincidentally, elevation went up / barometric pressure down in both cases), which produces an *extra* gain that is negligible compared with the actual climbing. Of course that leaves other errors (trees, coastline effect, etc), but temporal drift is clearly a minor effect.


Thanks for looking into that; that's neat to see. I had never actually quantified the barometric pressure skewing. It's definitely visible, but as you say, negligible.
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Re: Best method/device for measuring elevation gain riding

Postby utabintarbo » June 5th, 2013, 7:54 am

In addition to the issues above, the .fit files used in the Garmin x00 models tend to record elevation changes in blocky-looking jumps vs. the relatively smooth (but noisy) lines of the Edge x05 or x10 Garmin products (see the elevation graphs for this ride vs. this ride for an example - the first used an Edge 305; the second used an Edge 800, both at ILRA).

WRT your situation, the 205 series uses only GPS data (vs. GPS + barometric data) so it will be generally less accurate. However, if you are only looking for relative data on elevation on given routes, it is likely that any method/equipment used consistently will give reasonably valid results.

IMO, the Garmin Edge x05 models gave the best data for the price, but they are no longer in production. I currently have an Edge 800 and Edge 510, and find the 510 has eliminated the blocky data issue, and has little difficulty keeping the signal (which apparently was an issue on the 500). The budget solution spectrum starts with a used Edge 305, moves up through the x05 line, and stops with an Edge 510. I would avoid the Edge x00 series entirely.

HTH
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Re: Best method/device for measuring elevation gain riding

Postby bh357 » June 5th, 2013, 8:30 am

I don't recall off the top of my head the exact amount, but I've had close to 100ft of decending while riding the rollers. Garmin Edge 305 unit, with barometric altimeter.
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Re: Best method/device for measuring elevation gain riding

Postby i69whitey » June 5th, 2013, 9:04 am

Rode Bloomer Monday, approx. 1100 of climb, 1075 decending.
it took forever to climb down to the car.
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Re: Best method/device for measuring elevation gain riding

Postby 300hp » June 5th, 2013, 9:57 am

So,
broke out the trusty old 76csx. While I really, really, dislike the clunky and hard to navigate user interface, I do like its capabilities.

So, I have the ability to calibrate the altimiter by barometric pressure or known elevation.

Which method do you prefer, and what source do you get the applicable information from?

thanks!
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Re: Best method/device for measuring elevation gain riding

Postby c0nsumer » June 5th, 2013, 11:10 am

300hp wrote:So, I have the ability to calibrate the altimiter by barometric pressure or known elevation.

Which method do you prefer, and what source do you get the applicable information from?


You should do it based on known elevation. The best way is to find local survey markers and their known elevation. Lots of this is published online. If you have an airport nearby they'll have the elevation there as well, specifically designed for what you are intending: calibrating altimeters.
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Re: Best method/device for measuring elevation gain riding

Postby b_b » June 5th, 2013, 11:14 am

utabintarbo wrote:In addition to the issues above, the .fit files used in the Garmin x00 models tend to record elevation changes in blocky-looking jumps vs. the relatively smooth (but noisy) lines of the Edge x05 or x10 Garmin products (see the elevation graphs for this ride vs. this ride for an example - the first used an Edge 305; the second used an Edge 800, both at ILRA).

Wow 532 and 971 for same trail!
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