How well do you trust your Garmin's distance measurement in the woods?
NorthCascades
Posts: 10,968 Member
https://connect.garmin.com/modern/activity/3866173895
https://www.wta.org/go-hiking/hikes/mount-forgotten
Normally I don't care about this kind of discrepancy. I realize that good distance measurements are hard, and it's not like anybody is paying my by the mile. In this case, I'm trying to make a hard decision, and knowing how far I walked yesterday will be helpful.
My watch said 7.8 miles at the summit, and 15.9 when I got back to my car. I would be more suspicious if it thought the way up and down were wildly different lengths, but that's as close to perfect as you get.
I spent some time with a topo map, WTA's 4,300' of elevation gain is for the trip up, but doesn't include the way down. So the Garmin is closer to the truth as far as elevation goes.
It would be strange for their guide to include elevation but not distance to the summit. There the Washington Trails Association and you leave the trail to get to the summit, so that section might well not be included in the total.
I got 36,000 steps from the trip. It was a lot of woods, a broad canyon, and some gullies, all places where GPS tends to struggle.
https://www.wta.org/go-hiking/hikes/mount-forgotten
Normally I don't care about this kind of discrepancy. I realize that good distance measurements are hard, and it's not like anybody is paying my by the mile. In this case, I'm trying to make a hard decision, and knowing how far I walked yesterday will be helpful.
My watch said 7.8 miles at the summit, and 15.9 when I got back to my car. I would be more suspicious if it thought the way up and down were wildly different lengths, but that's as close to perfect as you get.
I spent some time with a topo map, WTA's 4,300' of elevation gain is for the trip up, but doesn't include the way down. So the Garmin is closer to the truth as far as elevation goes.
It would be strange for their guide to include elevation but not distance to the summit. There the Washington Trails Association and you leave the trail to get to the summit, so that section might well not be included in the total.
I got 36,000 steps from the trip. It was a lot of woods, a broad canyon, and some gullies, all places where GPS tends to struggle.
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Replies
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Are you using 3D distance/speed on your Garmin (I cant see your Garmin activity)? That might account for much of the difference if the website is listing a straight-line distance.
I use a Fenix 5S plus and mine is nearly dead-on for the trails I’ve been on (vs posted maps and/or trail race listed distance). I do not use 3D distance or speed on my watch as the maps I’m using for reference are straight line measurements. I’m in New England - our terrain is heavy on the forest, light on the canyons.1 -
I often run on heavily wooded rail trails to avoid the heat/sun and I noticed oddities with my pace. The pace on my watch will be off by as much as 45 seconds compared to my partner. And others in the group will all be somewhere in between. This does not happen when we are clear of the trees.
So, no, I don't trust my Garmin 100% but for distance it is 'close enough'.1 -
I've had issues with switchbacking trail. The Garmin will measure short because it cuts the switchbacks sometimes or if you are 5 feet above your previous location but in direct line of sight for the satellites, it will assume you haven't moved. When I had my watch set to autopause there were problems in heavy trees or rocks because if anything cut off the satellite then the watch would turn off, then turn on when it got the satellite again.1
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I reviewed the raw data one time to see the estimates for accuracy for each GPS point read.
It can start losing it a lot - but if trail in woods is decently straight and it gets good accuracy point read from time to time, the path and distance are pretty good.
One trip had lots of switchbacks in thick woods though and when I saw the track, I knew the distance was going to be way off. So obvious no need to look at raw data.
But it was backpacking - so trail distance already known.1 -
I've found ALL apps to be like this. Today I used MMW, a sister app to MFP. We walked 2.08 miles out, turned around walked 1/2 way back, left the trail to take a dirt track for .1 miles, turned around, retraced our steps to the exact spot where we left the original trail, then came on back to the truck, again following the original trail. I expected to come in at a bit over 4.16 miles. What did it give me? 3.97. lol I've had FitBit do this to me, MMW, MMF, Bartol, and a few other exercise apps. Now I just take all measurements as "approximates" rather than absolutes.
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I just bought a Garmin Instinct (previously using Suunto Ambit2R) and found the GPS is a lot less accurate than I've encountered. Enough that I complained to Garmin and they said they would refund me. The one thing they recommended was doing a GPS soak before you start your activity (stay in the same spot after the GPS lock has been made for about 5-10 mins so the GPS gets a better idea of where you are)1
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xrunlukerunx wrote: »I just bought a Garmin Instinct (previously using Suunto Ambit2R) and found the GPS is a lot less accurate than I've encountered. Enough that I complained to Garmin and they said they would refund me. The one thing they recommended was doing a GPS soak before you start your activity (stay in the same spot after the GPS lock has been made for about 5-10 mins so the GPS gets a better idea of where you are)
That is true - you can get a lock with still 100 ft of inaccuracy or more - just means you got 3 or 4 satellites with good data streams being monitored.
Sit for a bit and let that tighten up to 10 ft or better before starting out. Doesn't take 5-10 min though usually.
Unless in a rough area, in which case starting to move will likely put you right back into trouble again.
The Forerunner had a screen to view the accuracy, so I could decide when to take off.1 -
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I recall people commenting they'd put their unit in window and let it start while they finished getting bottles, putting on shoes, getting keys, ect.
Then outside with it for final minutes to tighten up accuracy, if it could be.1 -
my garmin(vivoactive) is pretty accurate. every once in a while i get odd distances. once i was in washington state for a few min (i live in wisconsin)
it's been accurate on the moraine trails here within .02mi0 -
I regularly run a loop through a heavily wooded trail. I can’t get a VO2max because of the trees, and I’ve noticed a 0.15 mile difference (over 4 miles) depending on whether I’m running clockwise or counterclockwise. (Clockwise is consistently the “longer” route.) I have no idea which is the correct distance, or if it’s somewhere in between - generally feel it averages out and is close enough for my own training purposes.2
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That's interesting - a consistent difference depending which way you go.0
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I’ve used mapmyrun to get distances for all the road routes I run, but this path is through the woods on private property in a rural area. I can pick out landmarks on satellite images but the path isn’t obvious, and I’ve even overlaid the Garmin maps of my run with the latest google maps images - each run varies pretty nominally.xrunlukerunx wrote: »I usually use an online tool or website (ie create a route in Strava) to check what the actual distance is so I know how accurate a run is2 -
NorthCascades wrote: »That's interesting - a consistent difference depending which way you go.
Agreed - I’ve joked that it must have something to do with running against the earth’s spin, lol.
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Duck_Puddle wrote: »I use a Fenix 5S plus
I currently am rocking a 235. It's about 3.5 years old. It's still working fine - but I'm thinking of upgrading to a Fenix sometime before the new year. Do you recommend it?1 -
TheNewKristin wrote: »Duck_Puddle wrote: »I use a Fenix 5S plus
I currently am rocking a 235. It's about 3.5 years old. It's still working fine - but I'm thinking of upgrading to a Fenix sometime before the new year. Do you recommend it?
I am a girl and have child sized hands. The primary reason I got the Fenix 5s was size (given that many of then functions are also available on other models). All my other Garmins have been approximately the size of my palm. I have zero regrets.
It has been through marathon (among many other races) training, miles of hiking and trail running all over the country, skydiving, swimming, regular workouts, biking, and whatever else I throw at it.
I like the training data and a number of the other included features (like all day stress monitoring-which is surprisingly accurate).
This probably the first device I don’t have any complaints about.
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Duck_Puddle wrote: »TheNewKristin wrote: »Duck_Puddle wrote: »I use a Fenix 5S plus
I currently am rocking a 235. It's about 3.5 years old. It's still working fine - but I'm thinking of upgrading to a Fenix sometime before the new year. Do you recommend it?
I am a girl and have child sized hands. The primary reason I got the Fenix 5s was size (given that many of then functions are also available on other models). All my other Garmins have been approximately the size of my palm. I have zero regrets.
It has been through marathon (among many other races) training, miles of hiking and trail running all over the country, skydiving, swimming, regular workouts, biking, and whatever else I throw at it.
I like the training data and a number of the other included features (like all day stress monitoring-which is surprisingly accurate).
This probably the first device I don’t have any complaints about.
I also have the Fenix 5S - I splurged on the Sapphire with the champagne metal band. Running, hiking, swimming, weight lifting, etc. - no complaints - and it doesn’t look out of place dressed up for work either. I love the thing as much today as the day I got it (Nov 2017).
I had a couple Polar watches and the Fenix 3 before getting the 5s. Zero regrets on upgrading.1 -
Interesting...
I had read through most of this thread previously and thought to myself, "this is more particular/detailed than I care about" and went on about my running.
Until today.
I forgot my 935 at home, so had to use my backup 920xt today. I ran a route I had mapped out previously, that I thought was 4 miles on the dot. I was surprised to hear my garmin ticking off the miles at a much longer-than-expected rate. I got back to the car and... 3.3 miles. WHAT?!?!! That can't be right.
I got back to my office a few minutes ago and looked at the data. Sure enough, 3.3 mile it tracked. But the mapped route was All. Over. The place. The route was basically an out-and-back, so the "back" track should have been pretty tight to the "out" track. Garmin says otherwise.
So I checked the pre-mapped route on mapmyride - yup, 4 miles. Hmmm...
Garmin tracks 3.3 miles, and the route tracked is significantly off.
MapMyRide plots 4 miles.
So n=1... I don't trust garmin, or at least I don't trust this garmin on these trails.
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Well, obviously you were going too fast for GPS to keep up!
During the satellite fixing, did you change screens to see the accuracy rate of where it was, even after it got a fix?
I know usually if I start out before it's as best it can be - it never seems to get better in sketchy areas.
Might check on 935 next time just to see.
I like to get down to 20 ft before I start moving.
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Well, obviously you were going too fast for GPS to keep up!
During the satellite fixing, did you change screens to see the accuracy rate of where it was, even after it got a fix?
I know usually if I start out before it's as best it can be - it never seems to get better in sketchy areas.
Might check on 935 next time just to see.
I like to get down to 20 ft before I start moving.
Satellite fixing?0 -
That's right, on those phones GPS always enabled or turn on auto when you start an activity (according to manual), and probably hides when it's just not using it, or when it needs to get a fix again.
"Starting an Activity
When you start an activity, GPS turns on automatically (if
required)."
Which means it's buried in the menus - this might show more info.
Changing the GPS Setting
By default, the device uses GPS to locate satellites. For more
information about GPS, go to www.garmin.com/aboutGPS.
1 Hold .
2 Select Settings > Activities & Apps.
3 Select the activity to customize.
4 Select the activity settings.
5 Select GPS.
- page 30 mentions this, which leads me to believe they did away with the extra details screens.
Acquiring Satellite Signals
The device may need a clear view of the sky to acquire satellite
signals. The time and date are set automatically based on the
GPS position.
TIP: For more information about GPS, go to www.garmin.com
/aboutGPS.
1 Go outdoors to an open area.
The front of the device should be oriented toward the sky.
2 Wait while the device locates satellites.
It may take 30–60 seconds to locate satellite signals.
Improving GPS Satellite Reception
• Frequently sync the device to your Garmin Connect account:
◦ Connect your device to a computer using the USB cable
and the Garmin Express application.
◦ Sync your device to the Garmin Connect app using your
Bluetooth enabled smartphone.
◦ Connect your device to your Garmin Connect account
using a Wi‑Fi wireless network.
While connected to your Garmin Connect account, the device
downloads several days of satellite data, allowing it to quickly
locate satellite signals.
• Take your device outside to an open area away from tall
buildings and trees.
• Remain stationary for a few minutes.
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Garmin did away with the satellite details page for their watches. What I've always heard is to have your pace displayed and don't actually start the activity until it goes to zero and stays there.0
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From the looks of the map above I bet you old watch was setup differently than you newer one.
My 5x displays a red ring when there's there no satellite fix, yellow when there are some, and green when it is ready to rock. I also have my settings to record every second and to use both the US and Russia signals.0 -
From the looks of the map above I bet you old watch was setup differently than you newer one.
My 5x displays a red ring when there's there no satellite fix, yellow when there are some, and green when it is ready to rock. I also have my settings to record every second and to use both the US and Russia signals.
What do you mean old watch vs new? New watch isn't a factor in this as it was home on my dresser the entire time.
The 920 just has GPS signal or it doesn't... My newer 935 does as yours does.0 -
From the looks of the map above I bet you old watch was setup differently than you newer one.
My 5x displays a red ring when there's there no satellite fix, yellow when there are some, and green when it is ready to rock. I also have my settings to record every second and to use both the US and Russia signals.
What do you mean old watch vs new? New watch isn't a factor in this as it was home on my dresser the entire time.
The 920 just has GPS signal or it doesn't... My newer 935 does as yours does.
You used your old watch and it came up short (or at least that's how I read it). The new watch may be setup to use additional satellites and may be taking readings more often.1 -
My Garmin GPS watch is sometimes off by quite a bit on trail runs. Usually I can see it on the mapping... it will show all the curves of the trail for a while, then an absolutely straight line for a while, then back to curving. Looks like the GPS couldn't connect for a while so the watch assumes I went in a straight line between the last GPS connection and the new one.1
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So the hike I asked this in preparation for is 18 miles by the book. I got lost a few times and did some side trips, my watch says I did 28.6 miles. A good friend went with me but ran, hers said 25. She believes it based on RPE and having done so many real rims of known length. RPE isn't a great guide though because one section was impossibly slow and difficult, and just draining. The track generally looks good, but if you zoom in enough it gets ... fuzzy? Like every step was a switchback.
https://connect.garmin.com/modern/activity/38919499320
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