# Big vertical feet discrepancies between Garmin products?



## bassn (Jul 12, 2011)

Just wondering if anyone out there is noticing a large discrepancy between varying Garmin GPS products. I went for a Skeggs ride today and my new Edge 500 showed 43xx vs my brothers Edge 305 at 49xx.... I wouldn't even care if it was just a hundred feet or so, but come one, over a 500 feet difference taking the same exact route???? What gives?


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## shiggy (Dec 19, 1998)

bassn said:


> Just wondering if anyone out there is noticing a large discrepancy between varying Garmin GPS products. I went for a Skeggs ride today and my new Edge 500 showed 43xx vs my brothers Edge 305 at 49xx.... I wouldn't even care if it was just a hundred feet or so, but come one, over a 500 feet difference taking the same exact route???? What gives?


Download the files and compare the tracks, too. Will bet the 500 has some straight lines where the 305 does not.

Garmin claims the satellite reception of the 500/800 is at least as good as the 305/705. My experience shows otherwise. I just received my 2nd warranty replacement 800 because of poor reception.


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## bassn (Jul 12, 2011)

shiggy said:


> Download the files and compare the tracks, too. Will bet the 500 has some straight lines where the 305 does not.
> 
> Garmin claims the satellite reception of the 500/800 is at least as good as the 305/705. My experience shows otherwise. I just received my 2nd warranty replacement 800 because of poor reception.


Thanks Shiggy. You are 100% correct, the 500 has significantly less curves versus the 305. I guess the 500 is going back and the 305 is back on the bike. Any other suggestions? I'll contact Garmin tomorrow and see what they have to say.


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## Guest (Dec 30, 2011)

When you say it " showed" the elevation difference between you and your brother, where do you mean, on the actual readout of the gps unit? or after uploading somwhere like garmin connect or strava?



bassn said:


> Just wondering if anyone out there is noticing a large discrepancy between varying Garmin GPS products. I went for a Skeggs ride today and my new Edge 500 showed 43xx vs my brothers Edge 305 at 49xx.... I wouldn't even care if it was just a hundred feet or so, but come one, over a 500 feet difference taking the same exact route???? What gives?


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## bassn (Jul 12, 2011)

diskus said:


> When you say it " showed" the elevation difference between you and your brother, where do you mean, on the actual readout of the gps unit? or after uploading somwhere like garmin connect or strava?


We had 2 Edge 305 units out there today and both read within 25 feet of each other, both on the monitor and after uploading. Comparing both routes the 500 definitely looks as though it was struggling for reception. The 305's routed the course map layout nicely and the 500 was segmented with a bunch of straight lines. Some area much worse than others.


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## redmr2_man (Jun 10, 2008)

305/705s read higher than 500s.

Is your 500 on second by second data or smart recording?


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## bassn (Jul 12, 2011)

redmr2_man said:


> 305/705s read higher than 500s.
> 
> Is your 500 on second by second data or smart recording?


It is set to default factory settings, which I believe is smart recording.


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## mbeardsl (Sep 9, 2009)

My 305 and eTrex set to their highest respective accuracy settings are still far off as the 305 collects every second and the eTrex does not. The 305s are known for "busy" elevation data however so I don't trust it either. I download all of my data into TopoFusion and correct the elevation data which brings everything into line between units as well as correcting for odd barometric oddities like starting in the early morning for a 6 hr loop and ending at a point 500ft above the same point when I started. The number I get from TF is by far the most consistent and subjectively "honest" number I've been able to derive.


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## Harold (Dec 23, 2003)

yes, there's variation between models. there's even variation between firmware versions.

measuring altitude by barometric pressure is an inexact science. best use requires frequent calibration to known altitude.

but you've stumbled across another issue: the smart recording debacle of the Edge 500 in particular. my experience is that smart recording on ANY device is no good for mtb use. you're going too fast on trails that have too many twists and smart recording doesn't keep up. smart recording is good for other situations, but sucks for mtb. 1sec seems to work best for mtb use. but I have had to dig into my gps' memory to dig out the autoarchived tracks when it hit the max tracklog length. 1sec is a memory hog.


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## mbeardsl (Sep 9, 2009)

What I get more frustrated with is the loss of milage with any GPS. On some of the more twisty trails I ride I lose almost 4 miles over a 22 mile loop vs an accurate computer with actual tire rollout. That's the worst example I have but it's pretty striking.

I haven't tried adding the speed/cadence sensor but I assume that must help somehow?


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## ACree (Sep 8, 2004)

bassn said:


> Just wondering if anyone out there is noticing a large discrepancy between varying Garmin GPS products. I went for a Skeggs ride today and my new Edge 500 showed 43xx vs my brothers Edge 305 at 49xx.... I wouldn't even care if it was just a hundred feet or so, but come one, over a 500 feet difference taking the same exact route???? What gives?


Saw a similar result on a road ride last sat. 2 800's were within about 20 feet of each for vert (2200), while a 500 was (coincidentally) 500 feet higher. That's per the data shown on strava after uploading the files. Another ride with the same riders had the 500 with a gps track that didn't even match up to segments on strava which I'd previously defined using a 310xt, while the 800 did hit the segments correctly.


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## pimpbot (Dec 31, 2003)

Wow. Glad I didn't 'upgrade' from my 305.


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## bassn (Jul 12, 2011)

I will try a ride tomorrow with the data recording set to every second. Well, hopefully I'll try riding tomorrow but a fall today left a softball size bruise on my bottom...ouch. Fortunately it's on the left outer cheek...lol. I will be running both the 305 and 500 side by side to see the differences.


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## Harold (Dec 23, 2003)

mbeardsl said:


> What I get more frustrated with is the loss of milage with any GPS. On some of the more twisty trails I ride I lose almost 4 miles over a 22 mile loop vs an accurate computer with actual tire rollout. That's the worst example I have but it's pretty striking.
> 
> I haven't tried adding the speed/cadence sensor but I assume that must help somehow?


using 1sec recording on my Oregon 450, I never vary by more than a few tenths of a mile on my local ~15mi ride.

Keep in mind, fitness GPS receivers are small. the smaller the gps, the smaller the antenna within that gps and those receivers wind up with poorer accuracy because of that.

too much disappointment comes from unrealistic expectations of what gps does/can do. the basic bike computer, when well-calibrated is a very accurate measuring device. if the most accurate measurements are what you want, a gps will not give you that. consumer gps receivers have an expected accuracy (on the good side within reasonable estimates) of 3-6 meters (and I've seen instances where they're off well over 20ft) for EACH point measurement. fancy survey-grade receivers that cost many thousands of dollars can get that down to the centimeter level with post-processing with differential corrections.


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## Moto'n'PushBiker (Sep 22, 2005)

I've read somewhere that altimeters with temperature sensors are much more accurate. AFAIK the 305/705 doesn't have a temperature sensor and the 500 does. That could be the source of the discrepancy (at least in areas with heavy tree cover where the GPS signal is weak).


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## Harold (Dec 23, 2003)

Moto'n'PushBiker said:


> I've read somewhere that altimeters with temperature sensors are much more accurate. AFAIK the 305/705 doesn't have a temperature sensor and the 500 does. That could be the source of the discrepancy (at least in areas with heavy tree cover where the GPS signal is weak).


Yes, a temp sensor does improve the accuracy of a barometric altimeter. Ideal gas law and all that.


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## shiggy (Dec 19, 1998)

NateHawk said:


> using 1sec recording on my Oregon 450, I never vary by more than a few tenths of a mile on my local ~15mi ride.
> 
> Keep in mind, fitness GPS receivers are small. the smaller the gps, the smaller the antenna within that gps and those receivers wind up with poorer accuracy because of that.
> 
> too much disappointment comes from unrealistic expectations of what gps does/can do. the basic bike computer, when well-calibrated is a very accurate measuring device. if the most accurate measurements are what you want, a gps will not give you that. consumer gps receivers have an expected accuracy (on the good side within reasonable estimates) of 3-6 meters (and I've seen instances where they're off well over 20ft) for EACH point measurement. fancy survey-grade receivers that cost many thousands of dollars can get that down to the centimeter level with post-processing with differential corrections.


Seems the 800 should work at least as well as the smaller 305, which it does not.

My 305 worked perfectly since 2007 until a few weeks ago when the altimeter freaked out and thinks it is at 65,616' until I start the timer when it drops to 34416'.
Records everything but the elevation.


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## Harold (Dec 23, 2003)

shiggy said:


> Seems the 800 should work at least as well as the smaller 305, which it does not.
> 
> My 305 worked perfectly since 2007 until a few weeks ago when the altimeter freaked out and thinks it is at 65,616' until I start the timer when it drops to 34416'.
> Records everything but the elevation.


it has a different chipset and OS, so who knows? I also do not know how the actual sizes of the antennas compare. how much of the internal space of the 800 is occupied by battery, memory, and touchscreen electronics?


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## bassn (Jul 12, 2011)

In short, should I just keep on using my 305 (which works perfect) and return the 500? The 500 was a gift and I'm sure my wife wouldn't mind me returning a cycling gift...lol.


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## shiggy (Dec 19, 1998)

NateHawk said:


> it has a different chipset and OS, so who knows? I also do not know how the actual sizes of the antennas compare. how much of the internal space of the 800 is occupied by battery, memory, and touchscreen electronics?


Garmin keeps says there are no reception issues with the 800--until I confirm I have all the updates and show them the ride files. Then they give me a RMA for a replacement unit.


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## Harold (Dec 23, 2003)

shiggy said:


> Garmin keeps says there are no reception issues with the 800--until I confirm I have all the updates and show them the ride files. Then they give me a RMA for a replacement unit.


Maybe they do have a problem that's not very widespread and you just happen to be able to tell there's a problem, and vocal enough about it to make them do right.


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## shiggy (Dec 19, 1998)

NateHawk said:


> Maybe they do have a problem that's not very widespread and you just happen to be able to tell there's a problem, and vocal enough about it to make them do right.


Having the 800 lose satellite reception 8-10 times during a ride (it does give you an audio and visual alert) is not exactly hard to miss. The perfectly straight line down a twisty 15 mile mountain trail is pretty obvious, too (shorter straight lines are more common).
This is the first replacement unit
Sandy Ridge, Edge 800 with frequent lost satellite connections by shiggy-wa at Garmin Connect - Details
Sandy Ridge with Edge 305. Solid satellite reception. by shiggy-wa at Garmin Connect - Details
Note that the straight line at the end of the 305 track is from the timer being stopped accidently.

This is from my original 800
OROR Super D race by shiggy-wa at Garmin Connect - Details
OROR Super D race by shiggy-wa at Garmin Connect - Details

OROR Super D pre ride by shiggy-wa at Garmin Connect - Details
OROR Super D pre ride by shiggy-wa at Garmin Connect - Details


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## Harold (Dec 23, 2003)

shiggy said:


> Having the 800 lose satellite reception 8-10 times during a ride (it does give you an audio and visual alert) is not exactly hard to miss. The perfectly straight line down a twisty 15 mile mountain trail is pretty obvious, too (shorter straight lines are more common).
> This is the first replacement unit
> http://connect.garmin.com/dashboard?cid=6277049
> http://connect.garmin.com/dashboard?cid=6277049
> ...


My Edge 705 suffered from the firmware update bricking a couple years ago. When I called Garmin support, even though there were plenty of reports of this happening on their own forums, support did not acknowledge a widespread problem. They still sent me a replacement as I was still in warranty, but I was done with the Edge after that.


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## Goannaman (Aug 11, 2011)

shiggy said:


> Garmin keeps says there are no reception issues with the 800--until I confirm I have all the updates and show them the ride files. Then they give me a RMA for a replacement unit.


That sucks. I'm crossing my fingers that mine keeps working, and hoping you get one that works soon.

I've only had one minor loss of signal during a ride. Feeling lucky about now.


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## WillieD (Nov 17, 2010)

I'm using a 305 and show differences in elevation climb of 1000 feet on the same 25 mi loop even though my total mileage is the same.


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## MYalias (Jan 10, 2012)

My 305 varies on the exact same loop every time. Not uncommon for mine to be off 100' per 10 miles. I don't think that's too bad


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## Camel Toad (Nov 23, 2011)

The last ride I went on, my buddy and I:
His Garmin Edge 705: Superhonky rode 18.7 mi and climbed 1,623 ft 
My Garmin FR 410: Camel Toad rode 17.2 mi and climbed 751 ft

He did ride a little loop I missed, but said there wasn't any climb and it was about .5 miles. The rest of the distance is due to my FR 410 failing to auto-resume right away, sometimes for a pretty long time.


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## Harold (Dec 23, 2003)

Camel Toad said:


> The last ride I went on, my buddy and I:
> His Garmin Edge 705: Superhonky rode 18.7 mi and climbed 1,623 ft
> My Garmin FR 410: Camel Toad rode 17.2 mi and climbed 751 ft
> 
> He did ride a little loop I missed, but said there wasn't any climb and it was about .5 miles. The rest of the distance is due to my FR 410 failing to auto-resume right away, sometimes for a pretty long time.


your FR410 lacks a barometric altimeter that the Edge 705 does have. elevation change from the Forerunner needs to have elevation corrections applied to it, which are usually calculated from 30m resolution DEM rasters, so any elevation change you see across ~90ft won't be measured, but it's still usually more accurate than the GPS altitude readings.

Auto pause sucks.


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## Eckstream1 (Jul 27, 2011)

No problems so far with my 800 that I got for Xmas...
I'll have to keep an eye on it and see how it reads after I ride the same trail again.

I have noticed that the distance seems a little short and the max speed was much lower than I expected from a familiar trail... At least compared to my previous computer.

FWIW, I have mine set to update every second and haven't lost signal on either ride...


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## bassn (Jul 12, 2011)

Well, I've used my 800 on several heavily covered trails since my last post and it has performed flawlessly. The only thing I changers was the data recording setting, from Smart to One second. Here are the places I've been to since - Mission peak, Wilders Ranch, Skeggs, and Demostration Forest.


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## spankye (May 7, 2007)

I'm on the fence to buy an Edge 500 and am wondering what battery/memory life is like when set to one second recording? I'll be clearing memory and charging after every ride. Most of my riding is either cx or mtn bike and i almost pulled the trigger on an edge 200 until i found out about one sec recording.


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## Harold (Dec 23, 2003)

spankye said:


> I'm on the fence to buy an Edge 500 and am wondering what battery/memory life is like when set to one second recording? I'll be clearing memory and charging after every ride. Most of my riding is either cx or mtn bike and i almost pulled the trigger on an edge 200 until i found out about one sec recording.


changing the recording frequency does not change battery life on a GPS. the device is on the whole time no matter what setting you use.


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## rramzjr (Jan 31, 2012)

gps on iphone sucks!


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## spankye (May 7, 2007)

NateHawk said:


> changing the recording frequency does not change battery life on a GPS. the device is on the whole time no matter what setting you use.


Cool,thanks. So the only thing it changes is file size then, correct? Does it matter how long you ride when you are in one second mode?


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## mbeardsl (Sep 9, 2009)

No, I've ridden for 18+ hrs no problem. Only issue I have had is if the unit runs out of juice the data can be very junky. If you can turn it off prior to that you'll be fine.


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## spankye (May 7, 2007)

mbeardsl said:


> No, I've ridden for 18+ hrs no problem. Only issue I have had is if the unit runs out of juice the data can be very junky. If you can turn it off prior to that you'll be fine.


Good to know. I'm riding the Dirty Kanza 200 this year and really want the battery power to capture the whole ride.


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## Harold (Dec 23, 2003)

I don't know how the Edge 500 handles files, but on my Oregon 450, max track size is 10,000 points. With 1sec recording, I have gone over that limit on longer rides, and the GPS autosaves the earlier track points in the archive and starts a new active tracklog. It's all accessible on the GPS when I get home, but if I want one continuous track for the ride, I have to stitch multiple files together before uploading.


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## spankye (May 7, 2007)

i'm guessing that for kanza i'll use the smart record since the roads are straighter and there isn't much, if any, tree cover. still, it may exceed the max amount of points you are talking about. maybe i'll try a road trip and record to find out, but that's getting off topic.


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