I am in the market for a GPS sports watch and I just stumbled across the Amazfit T-rex. It seems legit for the price. I am wondering if anyone has some real world experience with one? How accurate is it? Is it tough?
Amazfit T-rex GPS Sports Watch
My next "bike computer" will be a watch style but I want a really simple one. I don’t want or need the vast majority of features that the Garmins for example offer. I’ll be watching your post for activity though.
If you are riding/running/hiking in the forest and you care about accurate data keep in mind there is quite a range of GPS accuracy when it comes to these smaller devices. I did a trail run and tracked it with my phone, watch and a backpacking GPS then overlaid the resulting tracks and it was amazing how different they were and therefore how different the reported distance/elevation/etc... was. If you are out in more open areas moving in straighter lines the differences are less stark.
Last edited by: Vikb on June 7, 2022, 8:31 a.m., edited 1 time in total.
I would echo Vik B. Had one of the smaller garmin gos watches and it struggled to pick up satellite and maintain coverage across the north shore.
Using a garmin edge 530 now with no issues
FWIW I've been using a cheaper Amazfit watch (the Bip S) since the start of this year. In general it works pretty well, even in the forest. Most of the time the GPS is accurate enough for my needs but every once in a while the position seems to drift way off track mid-activity. On the map you can still recognize the roads or trails in the shape of the track but it's just transposed in a random direction. Also the elapsed time for the activity shoots up when this issue occurs. I like to think it has something to do with Einstein's theory of special relativity but more likely it's related to how the GPS antenna locks onto the different moving satellites.
Heart rate seems reasonably accurate but I have nothing to compare it to so take it with a grain of salt.
I'm not sure how helpful this is since the Bip S is less than half the price of the T-Rex. In my case I received the watch as a gift from a business relation so I'm not too bummed about the GPS issue. In general I can live with the occasional hiccup and when I want to make sure I'll have an accurate track I just use my phone to record a redundant track just in case.
Last edited by: [email protected] on June 7, 2022, 10:09 a.m., edited 3 times in total.
Reason: fixed typos
Here's an example of an activity where you can clearly see how the GPS went walkabout. This was an out-and-back ride from Lower Lonsdale to Dundarave. Sometime after the turnaround point the position is suddenly transposed in a northwestern direction. You can still recognize the route I took, just not in the right place. Also elapsed time shows as 4h 50m instead of 1h, moving time is still accurate though.
Last edited by: [email protected] on June 7, 2022, 9:54 a.m., edited 1 time in total.
One of the reasons I deleted Strava was due to the poor GPS in my iPhone 6. It had me cross the Cheakamus river and back where there is no bridge. My friend wanted to know where the new trail was.
Posted by: andy-eunson
One of the reasons I deleted Strava was due to the poor GPS in my iPhone 6. It had me cross the Cheakamus river and back where there is no bridge. My friend wanted to know where the new trail was.
My iphone SE2 has pretty decent GPS accuracy but it matters a lot where I store it on a ride. In my backpack or hippack it's good, in my shorts pocket it's sketchy.
It also helps to give it some time to get a good lock after starting Strava (or whatever GPS app). Even though it will say it has a GPS lock, you can often see it moving around a bit circling your actual location before it gets more accurate. I find if you wait for that before you start your activity it is more likely to stay on track.
The nice thing about the GPS watch is that the battery lasts very long and it's also easier to start/stop than a phone stored in a pocket.
Is there a way to see how accurate a device is? Some sort of rating or measurement?
They don't say much on their site.
Posted by: heathen
Is there a way to see how accurate a device is? Some sort of rating or measurement?
Not really, there are too many factors that can affect the accuracy of small GPS devices. Side-by-side comparisons like Vikb described are pretty much it, and even then you'd want to know if the testing was done in terrain, foliage, etc, similar to where you will be using it.
I have an old-school Suunto watch that is very accurate when running and biking on the Shore. It has a huge antenna compared to current watches, but it too exhibits the track "shift" phenomenon every once in awhile. I think it is a quirk of consumer grade GPS hardware that it occasionally gets offset somehow.
Posted by: heathen
Is there a way to see how accurate a device is? Some sort of rating or measurement?
They don't say much on their site.
No and I wouldn't trust anything the vendor tells you. If I was buying a new device I would look for an independent review. There are some sites/people that specialize in the topic and GPS accuracy is something they routinely cover.
I like this site. Here is the review for a watch I bought ---> https://www.dcrainmaker.com/2018/10/garmin-instinct-gps-watch-in-depth-review.html
If you scroll down you'll see a pretty good section on GPS accuracy. This GPS review is one of the more critical of this particular watch and also the most realistic now that I own it. So it always worth hunting down multiple reviews and using the most critical as your expectation baseline. Outdoor Gear Labs [usually a decent review site] rates the GPS accuracy more highly than I have found is achievable in practice.
Depending on how popular the device you are interested in is you'll have more or less review options.
If you can't find any reviews you are happy with, but you can return the product try it out against some other GPS options you own or can borrow and go for a ride deep in the forest. Lots of tree cover, steep slopes and tight twisty trails seem to test these devices the most. Obviously you want to enable the device's settings as much as possible to get the best performance [ie. faster position reporting catches corners better than slower, run in GPS only mode and the GPS + other satellites like GLONASS - either can be better so worth trying].
Posted by: heathen
I am in the market for a GPS sports watch and I just stumbled across the Amazfit T-rex. It seems legit for the price. I am wondering if anyone has some real world experience with one? How accurate is it? Is it tough?
Curious, are most on this thread finding Strava or Trailforks mapping inaccurate? Or losing cell service in places? This watch looks really good but. Lots of interesting features not in my phone, to be sure. Trying to figure out if I need the features of bringing another piece of kit.
Last edited by: craw on June 8, 2022, 8:20 a.m., edited 1 time in total.
Posted by: craw
Curious, are most on this thread finding Strava or Trailforks mapping inaccurate? Or losing cell service in places? This watch looks really good but. Lots of interesting features not in my phone, to be sure. Trying to figure out if I need the features of bringing another piece of kit.
Apps like Strava or Trailforks only interpret the data received from your phone's GPS chip/antenna or sync'ed from your GPS watch so their accuracy is almost entirely dependent on the quality of the GPS chip & antenna in your phone or watch. The interpretation of the data will still differ between the different apps which results in small differences in calculated distance, elevation etc. but that's just the nature of GPS.
For my simple tracking needs there is no significant difference in accuracy between my phone and my watch but the watch has benefits like the battery lasting 10X as long as my phone with GPS actively recording, easy access (on wrist vs phone in pocket/pack), water resistance for recording kayaking trips, etc.
Posted by: [email protected]
Posted by: craw
Curious, are most on this thread finding Strava or Trailforks mapping inaccurate? Or losing cell service in places? This watch looks really good but. Lots of interesting features not in my phone, to be sure. Trying to figure out if I need the features of bringing another piece of kit.
Apps like Strava or Trailforks only interpret the data received from your phone's GPS chip/antenna or sync'ed from your GPS watch so their accuracy is almost entirely dependent on the quality of the GPS chip & antenna in your phone or watch. The interpretation of the data will still differ between the different apps which results in small differences in calculated distance, elevation etc. but that's just the nature of GPS.
For my simple tracking needs there is no significant difference in accuracy between my phone and my watch but the watch has benefits like the battery lasting 10X as long as my phone with GPS actively recording, easy access (on wrist vs phone in pocket/pack), water resistance for recording kayaking trips, etc.
I was hoping this watch would be more accurate then my phone. My phone is better than most, but still makes mistakes.
Posted by: heathen
I was hoping this watch would be more accurate then my phone. My phone is better than most, but still makes mistakes.
Like Vik said, best to find some good independent reviews of the watch you are looking at.
Even with the best GPS receiver you can't rule out mistakes. Occasional GPS inaccuracies will always happen from time to time due to the nature of the system. If accurate tracking data is important, making redundant recordings using different devices significantly increases you chance of getting at least one accurate one.
The way I see it, it's actually pretty amazing a regular person can buy a relatively cheap device that fits on their wrist or in their pocket and have an accurate GPS signal most of the time. I once worked with a guy who had pioneered the first route planning software, to gather all the road data they drove around the country with GPS equipment that filled the entire trunk of their car and a big antenna on the roof.
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