# Most accurate GPS for MTB.



## FIF (Oct 5, 2018)

I was hoping some of you could please provide some accuracy feedback for your biking GPS while mountain biking. Please note that my main goal is for a handlebar mount GPS and NOT WATCHES as I need the quick heads up display for stats such as heart rate, speed, and time.

Currently I use a Wahoo Elemnt Roam and its accuracy for over the last year for off road has been extremely lack luster. The accuracy has been so poor that in many instances Strava will not recognize the segments as the Roam shows me being way off the trail. I have tried different mounting positions for the Roam with no success, so currently I am looking to get a new GPS to improve accuracy. I recently road with someone who used a Coros watch and it was way more accurate, but unfortunately a watch is not an option for me as I need the quick glance display.

Any suggestions or feedback would be greatly appreciated. A HUGE thanks in advance!

Edit:
Below are screen shots of one of the areas comparing my Roam (1st photo) to the Coros (2nd photo).


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## scottg (Mar 30, 2004)

My Garmin Edge 520, with the right settings, has been very accurate for mountain biking. The Edge 510 I had before it was also very accurate. My old Edge 500 was not. All have been primarily mounted on the bars.


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## Porkchop_Power (Jul 30, 2008)

For mountain biking you need to include a wheel sensor for top notch accuracy, especially on distance. Also play with the settings of using GPS, Glonass, Galileo. Depending on where you are a combination of one or more of these will improve accuracy.


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## acedeuce802 (Jun 30, 2017)

Porkchop_Power said:


> For mountain biking you need to include a wheel sensor for top notch accuracy, especially on distance. Also play with the settings of using GPS, Glonass, Galileo. Depending on where you are a combination of one or more of these will improve accuracy.


Just a note that Strava doesn't use wheel speed for segments and GPS devices don't correct their GPS with wheel speed. A wheel speed sensor is critical for getting accurate speed and distance for the activity, but it won't help at all with Strava segments. Strava segments basically measure the time when you cross the starting and ending gates, then do a check to make sure you didn't deviate from the path over a certain amount. Then they calculate your average speed for the segment based on the segment distance (which is often incorrect as it relies on the activity speed of the segment originator) and time elapsed.


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## Muggsly (Nov 9, 2005)

My 130 from Garmin is a bit more accurate than yours but not much and I am not sure I feel like spending the money for better accuracy. My GF runs a Garmin 25 and that thing is abysmal but the 130 is good enough for me to mark my own improvements.


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## evasive (Feb 18, 2005)

Consumer grade GPS has gotten very good and easy to use but there are inherent limits to the technology. Depending on where you are, what the vegetation canopy is, and how fast you’re moving, you might not get much better than that.


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## scottg (Mar 30, 2004)

Porkchop_Power said:


> For mountain biking you need to include a wheel sensor for top notch accuracy, especially on distance. Also play with the settings of using GPS, Glonass, Galileo. Depending on where you are a combination of one or more of these will improve accuracy.


Yes, the settings are really key on the Garmin. I use GPS/Glonass with 1 second intervals. I've no idea of those settings are available on the wahoo, but it might help.


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## Cary (Dec 29, 2003)

I went through this in deciding on which to purchase a few months ago and ran across multiple complaints about the Wahoo accuracy. Ultimately I went with a Garmin 130+, as Garmin appeared to be the most consistent. They are the Shimano of the GPS world, not always the most exciting, but work well for a fair price. The only thing I would do differently in hindsight is consider the 530 for the larger screen and longer battery life.


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## Porkchop_Power (Jul 30, 2008)

acedeuce802 said:


> Just a note that Strava doesn't use wheel speed for segments and GPS devices don't correct their GPS with wheel speed. A wheel speed sensor is critical for getting accurate speed and distance for the activity, but it won't help at all with Strava segments. Strava segments basically measure the time when you cross the starting and ending gates, then do a check to make sure you didn't deviate from the path over a certain amount. Then they calculate your average speed for the segment based on the segment distance (which is often incorrect as it relies on the activity speed of the segment originator) and time elapsed.


This is true for segments but a lot of us still go out exploring and riding where there are no segments. A wheel sensor will take what GPS showed as a 5 mile windy trail and correct it to 7 miles. It will also generally show a smoother route.


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## PTCbiker (Sep 15, 2020)

I have a Garmin 530 with wheel speed sensor and I assume it's very accurate. I've run 6 miles on a trail, measured by a vivoactive 3 watch. Then I've immediately ridden the same trail using my Garmin 530 and it was just shy of 7 miles.

I haven't played with sources for the 530, I assume the default is GPS.


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## Cerpss (Sep 13, 2015)

I know they had issue with drift earlier on, and I have had a case or 2, but I have had good luck with my Lezyne MegaXL. I've had it over 2 years now and think I've had 2 instances of drift. One in the summer when tree cover was at it's thickest and once in the snowy winter that I can't attribute a cause. Every once in a while it will totally glitch out where I have a long, straight line on my resulting track that is obviously wrong but not traditional drift. 

Last summer one of our local trails did a month of weekly strava "races". Ride it when you want, send in your gps track, they figure out the winner. This was on a pretty tight back and forth winding trail with some hills and decent tree cover over most of it. The race tabulator commented how accurate my tracks were compared to the other racers' using watches, phones, garmins, and his own wahoo.


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## Amt0571 (May 22, 2014)

I used a Dakota 20 for 7 years and now I'm using an Etrex Touch 35 and both seem really accurate to me.

Your track seems really bad, but not knowing the situation makes it difficult to evaluate. GPS can get confused on deep valleys or between buildings.


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## hammersorethumb (Sep 14, 2018)

This is a great source for head to head comparisons and reviews. he will put three or four devices on his bike and test them side by side. Incredibly thorough reviews. DC Rainmaker:
Sports Technology Buyers Guide: Winter 2020-2021


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## Harold (Dec 23, 2003)

Porkchop_Power said:


> This is true for segments but a lot of us still go out exploring and riding where there are no segments. A wheel sensor will take what GPS showed as a 5 mile windy trail and correct it to 7 miles. It will also generally show a smoother route.


While you are correct that it does report improved distances, you are dead wrong that the wheel sensor does anything for the recorded track. In a file from a head unit that has a wheel sensor, distance and speed are calculated using trigonometry with only 2 pieces of information: the position calculated by the GPS receiver and the time recorded by the GPS receiver. When a wheel sensor is used, those values are not calculated from the position. They are replaced with values determined from the wheel sensor. Some software (even Strava, if the uploaded file fails Strava's error check process) will toss wheel sensor data and calculate those values from the GPS coordinates and time. And sometimes you can force said recalculation to occur, as well.



Amt0571 said:


> I used a Dakota 20 for 7 years and now I'm using an Etrex Touch 35 and both seem really accurate to me.
> 
> Your track seems really bad, but not knowing the situation makes it difficult to evaluate. GPS can get confused on deep valleys or between buildings.


The track is definitely off (can't tell how much, since we don't know the accuracy of the shown underlying trails), but GPS doesn't get "confused". Rather, reflected signals (multipath error) just result in a large amount of error in a calculated position. Modern receivers can filter multipath errors out better than older ones, but there's still a lot of variation here that sometimes can be situational. Satellites that get blocked from view, resulting in the remaining visible satellites having a poor geometry will result in position calculations with lots of error, too. This is usually what's going on in terrain with lots of relief. Mountains, deep valleys, etc. Urban jungles (lots of skyscrapers) often both block signals and reflect them, and they can be a real challenge. Dense forests mostly have multipath errors, unless you're also in a forest in an area with lots of relief, where you might also have blocked satellites.


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## gat3keeper (Jan 24, 2015)

Igpsport

It uses various satellites available and have the option to select depends on your area. 

Can sync and auto upload data to strava too. 

Sent from my ASUS_X00QD using Tapatalk


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## chiefsilverback (Dec 20, 2019)

I use an Elemnt Bolt and the accuracy seems to be reasonable. Here are a couple of examples of the same trail ridden multiple times across different days, weather etc:

This is a really tight and twisty trail in places, 3 rides:









There are 6 or 7 lines here, sometimes I took in that 'loop' of the main trail, sometimes just plowed up the fire road:









A mishmash of trails on this one, but the tracks are pretty close on a given section:


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## 908811 (Apr 7, 2021)

Anyone compared a phone to the bike specific GPS computers? I would expect my old phone to perform better.


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## mtnbkrmike (Mar 26, 2015)

PTCbiker said:


> I have a Garmin 530 with wheel speed sensor and I assume it's very accurate. I've run 6 miles on a trail, measured by a vivoactive 3 watch. Then I've immediately ridden the same trail using my Garmin 530 and it was just shy of 7 miles.
> 
> I haven't played with sources for the 530, I assume the default is GPS.


I'm using a Garmin Edge 830 with a wheel speed sensor (which, intuitively, could just as easily be called a distance sensor), running GPS + Glonass. From what I have read, this should be reasonably accurate in mountainous terrain.

I don't get too stressed about this but on the other hand, if one is going to go to the effort of collecting and analyzing ride data at a granular level, it better be reasonably accurate.


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## Mudguard (Apr 14, 2009)

attention_to_huh said:


> Anyone compared a phone to the bike specific GPS computers? I would expect my old phone to perform better.


How would you know the real answer? Probably the best option is to run a wheel sensor. I use one with my Garmin 520 but I've never checked to see if the two bits of data are actually different. IE if the wheel sensor measures 9kms and the head unit measures 10kms. Guess I could disconnect the wheel sensor and try the two loops with it on and off.


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## Amt0571 (May 22, 2014)

attention_to_huh said:


> Anyone compared a phone to the bike specific GPS computers? I would expect my old phone to perform better.


I compared several phones over more than 8 years to a Dakota 20 and an Etrex Touch 35.

All phones were mid to high end and were crap in their GPS precission, and even worse when recording altitude.

Phones are so bad that I finally bought a GPS enabled watch that I always wear, to record rides or hikes when I unexpectedly want to record something and don't have the GPS unit with me.


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## 908811 (Apr 7, 2021)

They might not have gotten 4 satellites locked, I don't know how the service provision works with these things , perhaps though the GPS watches have better access to satellites ? You can still get a location from less then 4 but less accurate. Apparently GPS works on 1 second intervals , I wonder if our phones are stingy and ping every 3 seconds or something.

The hardware itself is dirt cheap, I would guess the antenna and service provision was more important unless the GPS watch used a 9dof to throw away dodgy GPS data .

**EDIT* looks like service provision has a lot to do with it. Apparently Hardware too as WAAS needs specific hardware.

15 m: Typical GPS position accuracy without SA.

3-5 m: Typical differential GPS (DGPS) position accuracy.

< 3 m: Typical WAAS position accuracy.



Garmin | What is WAAS?





Amt0571 said:


> I compared several phones over more than 8 years to a Dakota 20 and an Etrex Touch 35.
> 
> All phones were mid to high end and were crap in their GPS precission, and even worse when recording altitude.
> 
> Phones are so bad that I finally bought a GPS enabled watch that I always wear, to record rides or hikes when I unexpectedly want to record something and don't have the GPS unit with me.


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## 908811 (Apr 7, 2021)

Just based on them being high end expensive modern electronics and the GPS chip themselves being dirt cheap old tech. I think the antenna would be the most important.

Although the poster below you seemed to indicate otherwise from his experience.



Mudguard said:


> How would you know the real answer? Probably the best option is to run a wheel sensor. I use one with my Garmin 520 but I've never checked to see if the two bits of data are actually different. IE if the wheel sensor measures 9kms and the head unit measures 10kms. Guess I could disconnect the wheel sensor and try the two loops with it on and off.


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## Amt0571 (May 22, 2014)

attention_to_huh said:


> They might not have gotten 4 satellites locked, I don't know how the service provision works with these things , perhaps though the GPS watches have better access to satellites ? You can still get a location from less then 4 but less accurate. Apparently GPS works on 1 second intervals , I wonder if our phones are stingy and ping every 3 seconds or something.
> 
> The hardware itself is dirt cheap, I would guess the antenna and service provision was more important unless the GPS watch used a 9dof to throw away dodgy GPS data .


They were definitely locked to more than 4 sats.

I don't know why, but phone GPS is crap compared to Garmins. Its OK to get directions when walking or on the car, but recorded tracks are definitely more imprecise than a Garmin. Maybe it has something to do with antenna design. I don't know.


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## FIF (Oct 5, 2018)

attention_to_huh said:


> Anyone compared a phone to the bike specific GPS computers? I would expect my old phone to perform better.


Since starting this thread several weeks ago I've had a chance to do a bit of research as well as some testing of a few different GPS units (it should be noted that none of the GPS units had wheel sensors).

*IMHO, a phone or Garmin 1030 Edge Plus are the most accurate.*

The GPS units that I was able to test are the Wahoo Roam, Wahoo Bolt, Garmin 530, Garmin 830, and Garmin 1030 Edge Plus. In the effort of time, here is a quick snap shot of my distance findings when riding the same course over a short time as to not have much difference in vegetation/tree coverage:
*Phone: 9.32 - 9.41 miles (consisted of several rides and ran this in tandom with the GPS tests below).
*Garmin 1030 Edge Plus: 9.27 - 9.36 miles (over 3 rides).
*Wahoo Roam & Bolt: 8.36 - 8.61 miles (ran both side by side several times and showed similar results).
*Garmin 830 & 530: 7.76 - 7.85 miles (borrowed from friends / ran both side by side twice and showed similar results).

It should be noted that the test above was done on an extremely winding course through lots of trees and I tend to move at a pretty good pace which can make GPS drift add up quickly. *If this was done on a course that was a bit straighter or at a more relaxed pace, my guess is that the results would be greatly different.*

Now this is just purely my speculation, but accuracy might be improved with antenna size (as mentioned by others in the thread above) and possibly the power of the unit. While many bike GPS units are designed to be compact for convenience, the size could possibly affect the unit's ability to get an accurate lock when obstructed by trees; this could be why a phone or the larger Garmin 1030 seemed to be more accurate. Again, this is only my speculation so there is no need for the internet trolls to come out.

When comparing a single GPS over multiple runs, it seemed to show the same route and drift so they were fairly consistent from that standpoint.

Below are a couple of Strava screenshots that may help illustrate drift. The 1st pic is the phone, the 2nd is the Garmin 1030, and the 3rd is the Roam. I did not include the 530 & 830 since they were borrowed, only used twice, and seemed to be outliers when comparing mileage.




















After my testing, I have purchased the Garmin 1030 Edge Plus.

I should probably note that the main reason why I ride with a GPS on the handle bars is for the heads up stats screen which shows heart rate and avg speed; unfortunately the courses I ride would not permit me to look at a watch GPS without slowing down. And while it appears my phone may be more accurate, I am a little reluctant to put my phone on the handlebars as I am hoping a GPS is more resilient during those random gravity checks.

*Please take the information above with a grain of salt and understand that there are many variables which could affect performance. This is just my findings for my riding style on a single course. So again, no need for the internet trolls*.


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## PTCbiker (Sep 15, 2020)

Interesting results but I think a speed sensor would make all the difference on any of the Edge models. My experience with Garmin products is they're all reasonably accurate if the same generation across the range of models. I don't see why a 1030 is more accurate than a 530 since I think they came out out the same year.

The trails I ride and run are very twisty. Over a 7 mile track as measured by the 530, my Garmin vivoactive watch will be closer to 6 miles. Next time I ride perhaps I'll ride the exact same distance twice and measure it with and without the speed sensor.


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## iSeeker (Jun 18, 2017)

Just to understand terminology are you saying strava uses the wheel sensor when reporting the total activity distance and speed but not when reporting individual segments? Is that the main point? TIA


acedeuce802 said:


> Just a note that Strava doesn't use wheel speed for segments and GPS devices don't correct their GPS with wheel speed. A wheel speed sensor is critical for getting accurate speed and distance for the activity, but it won't help at all with Strava segments. Strava segments basically measure the time when you cross the starting and ending gates, then do a check to make sure you didn't deviate from the path over a certain amount. Then they calculate your average speed for the segment based on the segment distance (which is often incorrect as it relies on the activity speed of the segment originator) and time elapsed.


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## acedeuce802 (Jun 30, 2017)

iSeeker said:


> Just to understand terminology are you saying strava uses the wheel sensor when reporting the total activity distance and speed but not when reporting individual segments? Is that the main point? TIA


Correct. For example, a trail I frequent has the segment as the whole trail (so my whole activity was basically the same distance as the segment). Without a speed sensor, the mileage was reported as like 12 miles and 13mph, but the whole trail segment is 14 miles and I averaged 15.2mph. Another time I had a speed sensor, but forgot to change the calibration from another bike/wheel size, so it overestimated activity distance/speed. So I got like 15 miles and averaged around 16mph, whereas the segment was still reported as 14 miles and I averaged around 15mph (ran similar time as the first example).


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## NordieBoy (Sep 26, 2004)

acedeuce802 said:


> Without a speed sensor, the mileage was reported as like 12 miles and 13mph, but the whole trail segment is 14 miles and I averaged 15.2mph.


Strava segments also depend on what was used to create the segment in the first place.


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## richj8990 (Apr 4, 2017)

acedeuce802 said:


> Just a note that Strava doesn't use wheel speed for segments and GPS devices don't correct their GPS with wheel speed. A wheel speed sensor is critical for getting accurate speed and distance for the activity, but it won't help at all with Strava segments. Strava segments basically measure the time when you cross the starting and ending gates, then do a check to make sure you didn't deviate from the path over a certain amount. Then they calculate your average speed for the segment based on the segment distance (which is often incorrect as it relies on the activity speed of the segment originator) and time elapsed.


So if someone loads Garmin GPS data into their Strava app, it doesn't superimpose the more accurate time at all?

Here's another bummer, from the Strava website: 

We do not sync downhill segments to devices for Strava Live Segments. Please keep in mind that our system recognizes even the slightest negative grade so there may be segments that display a 0% grade that is considered downhill and therefore will not sync to devices.

So if Strava downhill times are off (ex. the moving time is faster than the posted activity time, even if you never stopped on the segment), then the Garmin's increased accuracy won't fix that because it only lets Garmin data sync with level or uphill segments???


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## NordieBoy (Sep 26, 2004)

richj8990 said:


> So if someone loads Garmin GPS data into their Strava app, it doesn't superimpose the more accurate time at all?
> 
> Here's another bummer, from the Strava website:
> 
> ...


Only for live segments.
They'll still sync to Strava no problem.


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## Hexsense (Aug 10, 2021)

My Garmin 530 is accurate on GPS location. But terribly out of sync on elevation.
Ride a loop and it shows where I stop is 200 meters lower than where I start, despute I start and stop at the exact same place.

Any idea why gps is good but elevation is wrong?


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## Harold (Dec 23, 2003)

Hexsense said:


> My Garmin 530 is accurate on GPS location. But terribly out of sync on elevation.
> Ride a loop and it shows where I stop is 200 meters lower than where I start, despute I start and stop at the exact same place.
> 
> Any idea why gps is good but elevation is wrong?


elevation measurements are vague guesses at best.

a barometric altimeter needs fairly frequent calibration to stay accurate. climbers know to do this.

the longer you're recording, the more opportunity you have for your barometric altimeter to drift because of changing weather. especially if you are out during fairly rapid changes in local barometric pressure, your altimeter will conflate it with changes in elevation. unless you calibrate frequently. which nobody riding bikes does. Garmin has a rudimentary "auto calibration" feature. it's not perfect. but it's better than never calibrating your altimeter.


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## Amt0571 (May 22, 2014)

Hexsense said:


> My Garmin 530 is accurate on GPS location. But terribly out of sync on elevation.
> Ride a loop and it shows where I stop is 200 meters lower than where I start, despute I start and stop at the exact same place.
> 
> Any idea why gps is good but elevation is wrong?


Calibrate the altimeter manually before every ride, and check that the continuous auto calibration is turned on.

My etrex touch 35 shows deviations of less than 15m between the start and the end if I do it this way.


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