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GUFFE33
08-10-2009, 04:22 PM
Hi

Have any one experience the same problem the the elevation gain is way of? I road a tip on bike 143 km in flat Denmark and the elevation gain was about 4700 meters. ?

That is way of....

I cant link to the route because Garmin connent is just loading and loading and nope map showing of my activity.

Have any one experience that problem as well...

I think it is bad you paid that kind of money for a product that is cearly this is in a beta verison...


Guffe 33

DW152
08-10-2009, 04:36 PM
The 310 does not have a barometric altimeter, which can be a pretty good way of measuring altitude. Instead, the 310 estimates altitude from GPS, which is not very accurate. I do not have any confidence at all in the accuracy my 310 or my FR305 provides. IMHO, it is so inaccurate that Forerunners probably shouldn't report an altitude value at all.

The data can be post-processed (like MotionBased used to do) to give reasonably accurate elevation gains and losses, but GarminConnect currently does not do this. Supposedly, this capability will be brought into GC sometime in the future.

PLENTY2RUN
08-11-2009, 01:43 AM
...I do not have any confidence at all in the accuracy my 310 or my FR305 provides. IMHO, it is so inaccurate that Forerunners probably shouldn't report an altitude value at all....

I do not agree. The accuracy may not be so good but good enough for me while mountainrunning. For me it's an important feature while training or racing in the mountains because monitoring altitude is more important than distance. And it isn't that inaccurate, is it? I plotted several times the track on a detailed map and the accuracy mostly reaches 50m. Only in canyons it's bad.
At the moment I still (only) have the 305 and I hope the 310 does the elevation-job as well as the 305?

DW152
08-11-2009, 04:51 AM
I don't know much about mountaineering, so I don't know if it's accurate enough for you. However, IMHO my Forerunners haven't been good enough for running. My FRs have claimed that I gained and lost more elevation running on the beach than running through the hills in my neighborhood, and the run-to-run variation over the same course has also been high. When I used to run with a watch that had a baro altimeter, I could look at the altitude graph and figure out which hill corresponded to eachbump in the graph, but I wasn't able to do that with my FR.

ALAALA
08-11-2009, 05:07 AM
It has really nothing to do with Forerunners or even Garmin. It is a feature of GPS technology itself. This is, btw, a FAQ.

Hopefully accuracy will get better when(ever) the systems (GPS and GALILEO) transmit dual-band signals for free usage, so that people like Garmin can draw from that.

PLENTY2RUN
08-11-2009, 07:42 AM
When analyzing in SportTracks (with Rounding setting elevation set to 90) I get satisfying results (+/- 10%), compared with the figures of the Organization of a race (totals up and down).
And using the elevation during running I have enough accuracy to know how much vertical meters to go.
But of course, more accuracy would be nice!

GUFFE33
08-11-2009, 12:43 PM
I toke a ride on 40 km and the elevation gain was 2000 meter... I is like a ride mountain. The highest point in Copenhagen is 40-50 below sealevel...

Elevation is total useless...

EKUTTER
08-13-2009, 10:36 PM
Compared to using my Edge 705 or my Polar RS800 (both have barometric pressure), the 310XT is often off by more than a factor of 3 (600' vs 2000') and is allways way over. Everytime I look at the altitude, it seems fairly accurate. But when you download the data and compare the ascent to a more accurate device, it is obvious how useless the 310XT is for actual ascent. I suspect that is why they don't even give you the option of showing "ascent" as a field on the unit itself. The Edge 705 does let you display this.

MARTINSMAC
08-19-2009, 03:59 AM
I find the elevation to be reasonably accurate on 305. It's typically within ten metres, albeit with some spikes when sattelite coverage is poor, which is not suprising as it's totally dependent on good coverage.

I've compared the readings with those on my Oregon 300, which has a Barometer and they're usually very close - I personally find the calibration of the Barometer to be such a pain that detracts from the potential accuracy.

FOLLOWBEN
08-22-2009, 10:43 AM
I've got the same problem.

On any given activity, the starting elevation is correct & corroborated by OS maps. However on an average bike ride the data from my 310XT in TrainingCenter is 1.8x that of my mate's Garmin 605, which is pretty accurate according to those same OS maps.

It only gets worse when I upload the data to Garmin Connect, where it can be anything between 2-3 times the values from the 605 :(

I've contacted Support and am awaiting a reply. Be interesting if they say the same as @DW152. If so, I'm with @EKUTTER: why bother reporting the data at all if it's fundamentally incorrect?

JJJHAWK88
08-24-2009, 09:21 AM
Thank you everyone for posting good information.

The elevation discrepency seen within the FR310XT is an issue we are aware of and plan to have corrected in a future update. I am not quite sure the time frame but as I collect more information I'll make sure to keep this post updated.

Regarding GPS elevation data, there are many users who still like to have an elevation value along with total ascent/descent displayed. GPS elevation has a higher probability of inconsistent readings but the values can improve throughout a workout and many times be within 200ft and sometimes less compared to barometric altimeter elevation readings.

jjjhawk88

LONDONJ2009
09-22-2009, 04:02 AM
Am I right in thinking this is not addressed in the v2.6 firmware update?

At the least it would be good to have an option on Connect to fish the elevation data out of Google Maps and correct it accordingly.

JJJHAWK88
09-22-2009, 07:31 AM
You are correct this is not resolved in software version 2.60. We are working to resolve this as soon as possible.

It would be nice to convert .klm files from Google Earth to .tcx file but doing a quick search I didn't see anything that would offer such an option.

-jjjhawk88

CSTUEMER
09-22-2009, 07:43 AM
You are correct this is not resolved in software version 2.60. We are working to resolve this as soon as possible.

It would be nice to convert .klm files from Google Earth to .tcx file but doing a quick search I didn't see anything that would offer such an option.

-jjjhawk88

http://www.teambikeolympo.it/TCXConverter/TeamBikeOlympo_-_TCX_Converter/TCX_Converter_ENG.html

LESFAUFAU
09-22-2009, 09:29 AM
I have used a forerunner 305 and have just bought the 310 xt

The elevation date on the 305 is not very good...but it is completely off with the 310xt
As an exemple, a run along the Thames from Hyde Park to Greenwich foot tunnel results in :
- 2246 meters elevation gain / 2281 meters elevation loss with 310xt
- 493 meters elevation gain / 493 m elevation loss with 305

Readings from 310xt are typically 3 to 6 times those of the 305

So far, my enquiries to Garmin have remained unanswered

LONDONJ2009
09-23-2009, 06:01 AM
Thanks, good to hear you're working on it.



It would be nice to convert .klm files from Google Earth to .tcx file but doing a quick search I didn't see anything that would offer such an option.
-jjjhawk88

It is possible to convert kml to tcx and vice versa. The following app does it: TCX Converter (http://www.teambikeolympo.it/TCXConverter/TeamBikeOlympo_-_TCX_Converter/TCX_Converter_ENG.html). Also, web services like GPSies do it.

It would be pretty straightforward to approach the developer above and make an offer to license it. (It's donateware.) Amusingly, the developer claims the software is used by Garmin-Slipstream...

R.MCLACHLAN
09-23-2009, 04:28 PM
Elevation is pretty useless on the 310XT. I ran a loop starting and finishing at the same point. There was a variation of 14m on the elevation at the start/stop position!

Hopefully Garmin will address this quickly.

SEILOGRAMP
09-23-2009, 04:34 PM
Elevation is pretty useless on the 310XT.

Certain issues can be tweaked via firmware update. However, it's not specifically a Garmin issue that GPS technology does not permit more accurate elevation data. This is the main reason that Garmin has added a barometric altimeter to some devices, such as the Edge series.

R.MCLACHLAN
09-23-2009, 04:47 PM
I agree that barometric elevation would be preferable to GPS elevation and that no firmware update can correct the inherent limitations of GPS. However a difference of 14m on the same start/stop point is an indication of something wrong somewhere.

SEILOGRAMP
09-23-2009, 07:09 PM
Try resetting the satellite cache. Hold the down arrow while powering on. Then leave the unit still with a clear view of the sky until the accuracy gets down to less than 20 feet. Could be the unit has some bad satellite info. Also, make sure you have the latest firmware for the 310xt.

LONDONJ2009
09-24-2009, 12:35 AM
I understand the limitations of not having barometric pressure. (Which is surprising and curtails its usefulness as a bike computer in my opinion, but a fact nonetheless.)

However for those of us who at least want our records to be accurate post hoc, allowing map data from Google to override the satellite elevation data once the record is uploaded to Garmin Connect would be a reasonable option.

HENNIEVN
09-24-2009, 10:27 AM
Currently I export to SportTracks (free program) and there is a facility to do altitude correction at the push of a button. Exporting to this program also allows viewing data in a few more variations than is possible with the Garmin site, so is quite useful. I do not believe my running cadence sensor is exported from Connect, all other data seems OK - this issue may be on the SportTrack side.

Hennie

PHILIPSHAMBROOK
09-24-2009, 02:13 PM
Currently I export to SportTracks (free program) and there is a facility to do altitude correction at the push of a button. Exporting to this program also allows viewing data in a few more variations than is possible with the Garmin site, so is quite useful. I do not believe my running cadence sensor is exported from Connect, all other data seems OK - this issue may be on the SportTrack side.

Hennie

SportTracks is donationware, not free technically. If you use it, support them.

BIGDAD13
12-28-2009, 06:59 AM
I am also having huge discrepancies with elevation. I live in a very flat area and I am know that the elevation changes VERY little over the course of ANY run I am likely to do (South Florida). I am on a Mac so the Sports Tracks program will not work for me. I like the suggestion to allow Google Maps to override the data on the device.

It is troublesome that the top of the line FR310XT does not have better accuracy...and the comment that the Edge series is better in this regards is like saying "You spend $400 for a device that does not work well enough. To fix it, you need to spend $400 more and attach another device to your body". :eek: I understand the differences in technology...but it still 'hurts' to hear that this feature is not REALLY a feature.

DW152
12-28-2009, 07:31 AM
If you're on a Mac, you might try Ascent. It smooths the elevation data and will correct it a little bit. Having said that, I've also done some runs on the beach (with a 305) that showed preposterous elevation gains and losses, even after corrected by Ascent.

I agree with you that Garmin should probably stop advertising that any of the Forerunners give meaningful elevation data.

RVDOWNING
12-28-2009, 08:11 AM
RunningAhead (http://www.runningahead.com) also has an altitude correction option. Also, you can upload your data directly from your 310xt device.

EKUTTER
12-28-2009, 11:48 AM
Any algorithmic smoothing of the altitude data is still going to be insufficient. The best method for altitude on the 310 is using a database to translate coordinates into altitude. I believe Sport Tracks has a plug in that does just this. I believe you can also do it to a single file using http://www.gpsvisualizer.com/elevation. It still has problems though. Cross a bridge over a gully and the profile will show you going down and up, not straight across.
I was definitely disappointed that the 310 didn't include barometric pressure for the altitude as all the high end Polar watches have done for years. Garmin may have thought it risked water leakage, but you'd think they could figure out a way. Maybe Garmin incorrectly assumes runners and triathletes don't care about vertical!

RVDOWNING
12-28-2009, 12:08 PM
RunningAhead does not use algorithmic correction. it goes against a database of actual altitudes (presumably Google) based on latitude and longitude.

JJJHAWK88
12-30-2009, 09:59 AM
As an fyi...we did release software version 2.70 (https://buy.garmin.com/shop/store/downloadsAgree.jsp?product=010-00741-00&cID=142&pID=27335)and we did improve the elevation readings.

Since you are still relying on GPS elevation to provide elevation data there can be discrepencies, but the update should help improve the information.

jjjhawk88

THOMPD13
12-30-2009, 09:58 PM
As an fyi...we did release software version 2.70 (https://buy.garmin.com/shop/store/downloadsAgree.jsp?product=010-00741-00&cID=142&pID=27335)and we did improve the elevation readings.

Since you are still relying on GPS elevation to provide elevation data there can be discrepencies, but the update should help improve the information.

jjjhawk88

Great device! The ongoing firmware upgrades are encouraging (thanks everyone who requested the last lap data)! There is still work to do on the elevation front.

I upgraded to 2.7 before a 16 miler last Saturday that was made up of a 4 x 4-mile loop. The elevation readings at the low point of the route varied by 30' from lap-to-lap. And the relative height of the hills was all over the charts (including some downs that should have been ups).

From an elevation standpoint, the height of hills within the course is what I care about most. For now, it doesn't look like the 310XT can provide that level of elevation data in a reliable way. Here's hoping elevation functionality continues to improve.

JJJHAWK88
12-31-2009, 08:37 AM
As an additional side note, the following describes some of the complications with regard to "GPS elevation (http://www.ja-gps.com.au/what-is-gps.aspx#elevationreadings)".

Essentially, the only way to smooth this data, is to continue tweaking the algorythem or use a barometric altimeter. As stated above, there are programs that can continue to smooth the data, but there is a fine line because tweaking and smoothing can create other problems. Also, even adding a baro altimeter can yield errors. Certainly not always as great of an error as GPS, but error none the less.

Good feed back from the community and we will certainly continue looking into ways this kind of information can be improved.

jjjhawk88

STARWATCHERDE
12-31-2009, 09:01 AM
any measurement is only as good as the underlying equipment. A switch to a barometric altimeter would surely be the logical consequence. These types of watches were already sold in the mid-ninetees when I used them for recording purposes during mountain biking tours. I see no real sense in further datacrunching by smoothing algorithms et al. - these are useless discussions and lead to no acceptable progress.
The technology is on the market for nearly two decades and I would expect that Garmin is able to manufacture this into 3xx devices in the next generation as well.

DW152
12-31-2009, 09:19 AM
The technology is on the market for nearly two decades and I would expect that Garmin is able to manufacture this into 3xx devices in the next generation as well.

I agree, and so did a lot of people when the 310xt came out -- we were really disappointed that it didn't have a barometric altimeter. I realize they're not perfect, but they are far better than GPS, which really isn't useful. Before I got my first Garmin, I had a Suunto T6 with a barometric altimieter, and it worked great. Since the T6 didn't have GPS, when I was looking at the data afterwards I could use the altitude profile to figure out where key things happened during my workout. I realize that Garmin has to make tough choices on what features to include or not, but that's one thing I would have paid a lot extra for.

(And -- if they really wanted to do it right -- they would have a swim mode for the 310XT++ (new version with baro altimeter) that locks out the barometric altimeter while swimming. As I said, my T6 worked great, but when I swam with it, it would record huge altitude gains and losses, because everythime I plunged my hand into the water, it would cause a small pressure spike that the barometric altimeter would record. Do that a bunch of times over an hour, and I'd get 50,000 feet of elevation gain and loss:eek:)

BEOIRANDSHAM
01-02-2010, 10:05 AM
I use the 310xt Kayaking downstream on a flatwater section of river with a guaranteed gradual descent yet my elevation increased by 33 ft over 0.31 miles. Does this inaccuracy effect speed or pace over distance travelled?

Personally I would prefer to disable the elevation 'feature' if it cannot give accurate readings.

EKUTTER
01-02-2010, 10:40 AM
As for disabling the BP altitude while swimming, I actually found that useful on my Polar during Triathlons. It made it really easy to separate when I came out of the water from when I actually ran over the timing mats (often a few minutes later). On further though, I guess I can now figure that out via the GPS track overlaid on a map. A specific swimming mode could also be good since they could probably come up with an algorithm specific to swimming to smooth out the track and get decent distance on the fly.

In any case, BP altitude really is a key feature for this kind of device. That would be enough to get me to shell out another $350 to upgrade.

ALAALA
01-02-2010, 01:17 PM
Does this inaccuracy effect speed or pace over distance travelled?


This is a top rated FAQ, asked and answered many times.

The Forerunners do not integrate altitude data into the distance
calculations and thus not into the speed/pace calculations.

Even for hilly trails, this has little consequence, and is in practice
shadowed by the inherent GPS error marginals.

DW152
01-02-2010, 05:26 PM
I use the 310xt Kayaking downstream on a flatwater section of river with a guaranteed gradual descent yet my elevation increased by 33 ft over 0.31 miles. Does this inaccuracy effect speed or pace over distance travelled?


Here's a little more discussion on this:

https://forums.garmin.com/showpost.php?p=13884&postcount=3

DW152
01-02-2010, 05:29 PM
As for disabling the BP altitude while swimming, I actually found that useful on my Polar during Triathlons. It made it really easy to separate when I came out of the water from when I actually ran over the timing mats (often a few minutes later).

Interesting. I never thought of that. Actually, I was just sort of half-joking, trying to fend off the inevitable vocal complaints that people would post on these forums when their watch recorded a crazy high elevation during the swim with a baro altimeter. I'd be happy if Garmin would just provide a "swim" mode for the 310, instead of making us choose "other."

TRYING2GOFAST
01-03-2010, 04:25 PM
As an fyi...we did release software version 2.70 (https://buy.garmin.com/shop/store/downloadsAgree.jsp?product=010-00741-00&cID=142&pID=27335)and we did improve the elevation readings.

Since you are still relying on GPS elevation to provide elevation data there can be discrepencies, but the update should help improve the information.

jjjhawk88


Improved enormously. Thank you.

BEOIRANDSHAM
01-03-2010, 05:28 PM
Thanks.

PHILIPSHAMBROOK
01-03-2010, 06:04 PM
I am getting the impression that the elevation data more closely approaches reality with 2.7. :D

Problem is now that the numbers do not look as impressive and bragging rights are accordingly reduced :eek:

DW152
01-03-2010, 07:24 PM
I'm not convinced the elevation is improved with 2.7. They numbers still don't make sense.

One example: three days ago I did one 4.6 mile lap around a local lake. The path is pretty flat. I'd doubt that there is 100 feet total elevation gain and loss total. The 310 says I had 525 feet of gain and 607 feet of loss (note that I stopped and started at the same place). This morning I did two laps on the same path, and it says I did 607 feet of gain and 663 feet of loss (I did stop and start at the same place again, too) -- even though I ran around the lake twice this time.

Another 7-mile run I've done twice in the last two of weeks. It's got some hills on this route. The elevation gain and loss from the most recent time I did it is twice as much as when I did it two weeks ago. Elevation gains and losses for those runs, which were quite hilly, are less than the runs around lake on the flat path.

As far as I can tell, nothing has changed.

TRYING2GOFAST
01-07-2010, 02:56 PM
Problem is now that the numbers do not look as impressive and bragging rights are accordingly reduced :eek:

Same problem we're having with the calorie computations. :p

EKUTTER
01-07-2010, 04:11 PM
That total ascent has definitely improved for me since 2.7. Today I did a 16 mile run that showed 1070'. That compares to 720' by calculating the altitude based on coordinate look up which tends to match pretty close to my Edge with barometric pressure. In the past, the total ascent shown on the 310xt was generally 3 times the post processed value. 30% error is definitely better than 300%! I had a friend who was convinced he was always doing over 2000' on his 7 mile runs around town.

Unfortunately the 310xt graph still shows some pretty big hills along a totally flat trail along a lake. Some new laws of gravity!

So the ascent seems to generally be much more accurate and almost usable. The graph can still be pretty mis-leading. Bottom line is I doubt this can ever be sufficiently accurate to keep us satisfied without barometric pressure.

MEXIDOGS
02-14-2010, 02:58 AM
I've recently upgraded to the most recent software for my 310XT and did a surfski race last weekend and apparently I dropped 27m over the first 7km of the race and then climbed back over the next 8km. Interesting given the race was on relatively flat water in the ocean.

Based on this, IMHO the elevation function on the 310XT isn't worth using as its accuracy is rubbish.

IANMCSHANE
03-13-2010, 05:20 PM
I found this thread whilst searching for possible solutions to wildly inaccurate elevation readings on this device.

I've had a 310xt for 4 days now (upgraded to 2.7fw immediately) and I think I will be sending it back on Monday whilst it still falls under the '7 day cool off' period for online purchase.

Combined with other problems (crazy speed changes, taking up to 5 minutes to get satellite signal in open areas whilst my iPhone does it in 30 seconds...), this is the straw that breaks the camels back.

I start my runs on a seafront, around 3m above sea level. This morning, this Garmin 310xt had me at 400m above sea level. WTF?

I've been using Runkeeper (an iPhone app) for the past year and it manages to get the elevation correct.
Whether that is down to more sophisticated hardware in an iPhone 3GS vs a 310xt, I don't know. But, it seems I spent 250 on a device that *should* be much better but is probably comparable and perhaps actually WORSE than a 7.99 software application running on an iPhone 3GS.

Annoyingly, I spent a fair amount of time researching this device and found nothing bad to say about it - with the exception of no HRM and GPS in swim. Maybe most people don't use it to it's full extent? Or is this perhaps something to do with a bad batch of devices?

EKUTTER
03-13-2010, 06:57 PM
Any reviews you read must not have been by actual users. I don't know any user that would speak positively about the altitude features on the watch. Basically, any device that bases altitude off of the GPS signal is going to be pretty close to unusable. They made some improvements in the last firmware upgrade but it still doesn't give accurate enough results to be of much use. I actually wish they would give you an option to disable altitude features all together and use the processor resources for other calculations.

You still can get reasonable altitude numbers with post processing software that takes the GPS coordinates and looks up the altitude in a database. This still has some issues but is much better than the GPS only based altitude. SportTracks is the most common software used on this site but there are a number of other programs that will do this including some online sites.

Garmin sports devices in general have problems with altitude. There is a long running thread for the Edge 705, which has barometric pressure, concerning altitude problems, especially since the last firmware upgrade.

As for the satellite lock taking 5 minutes, it shouldn't take that long, usually 30 seconds max. But, if you try to do it inside or while moving, it will likely take much longer.

The iPhone isn't necessarily a good comparison because it uses the cell signal and tower locations to help it get a fix on the satellites. The FR310 obviously doesn't have this ability.

I suspect most of the reviews you read were for professional publications or by reviewers that don't actually use the watch on a regular basis. They tend to gloss over any negatives or rely too much on the Garmin marketing and don't really understand how these things are used.

Despite all the problems, most people I know that have these (15 just in my triathlon group) would hate the part with it.

PHILIPSHAMBROOK
03-13-2010, 11:53 PM
Agree with all EKUTTER has said. This device has never, as far as I am aware, been sold as a device for accurate measurement of elevation. I would suggest that anyone purchasing this device with that expectation failed to ask the relevant questions or failed to research the device properly.

Satellite lock on our devices is always fast in open areas. The only caveat is that the device should be static. If anyone is consistently having problems gaining satellite lock in open areas then Garmin Support should be contacted.

I think we pretty much use ours to their full capability, ie as a sports training device. We do not use them as mapping devices. We do not use them for measuring altitude.

IANMCSHANE
03-14-2010, 04:38 AM
Hi,


Any reviews you read must not have been by actual users. I don't know any user that would speak positively about the altitude features on the watch.

It's not that anyone spoke positively about it, it wasn't mentioned all.



Despite all the problems, most people I know that have these (15 just in my triathlon group) would hate the part with it.

That's a good thing to note, thank you.


This device has never, as far as I am aware, been sold as a device for accurate measurement of elevation.

Interesting point of view. I didn't buy my car as a device to play CD's but if the sound unit didn't work correctly when I bought it I'd still be annoyed.

EKUTTER
03-14-2010, 10:54 AM
That's the problem with most "official" reviews by people who don't use these things on a daily basis. They don't even know the right questions to ask. They look at the marketing material, "oh, it does altitude", they play with it a bit, "oh look, it is giving me altitude numbers", and then write their happy review. They don't know enough to follow up and realize the numbers are pretty bogus.

Most (but not all) dissatisfaction with the device has been due to unreasonable expectations, such as why doesn't this thing give accurate distance while swimming. Many of us were disappointed when they announced the product with no barometric pressure for altitude, but at least at that point we knew altitude would be inaccurate.

Garmin always seem to have a lot of problems with the firmware when new devices come out but they are pretty good about fixing those problems over time. Initial release problems are one area where dissatisfaction is completely justified. Luckily, most of the real bugs with the 310 of been worked out. Now it is just improving the existing feature set.

Each generation of these devices gets a bit better, and it really is amazing what they can now put on your wrist, but we always want more.

GMSAXTON
03-14-2010, 11:50 AM
I have only used the 310XT with firmware 2.7, and almost entirely use the watch for trail running.

I find elevation to be surprisingly accurate (+/- 50 feet) based on comparisons to topographical map data, 'official' race elevation maps and Google Earth. I've used real-time elevation data in races to determine how much is left of an uphill climb. I typically use peaks with unobstructed views from the sky to benchmark my watch data since they are also nicely marked on topo maps.

Whatever the algorithm or other technology being used, it works at least for my trail running purposes.

Now, elevation GAIN or the total ascent measurement is entirely different and I get very inconsistent numbers from the watch, SportTracks and race organizers. As we know, smoothing has a lot to do with those calculations anyway. I do not in any way rely on these numbers.

But, elevation itself has been very useful in helping determine where I am on a hill.

I suspect that the accuracy of the elevation data will be more prone to error on lower grade hills and rolling hills since the elevation changes are subtle anyway and GPS itself introduces measurement error.

IANMCSHANE
03-14-2010, 11:54 AM
I completely agree with you, which is why I didn't really read much into the reviews by the usual suspects but actually looked at 'real' users, through blogs and tri forums. Granted, for some reason I didn't spend much time looking through this forum here.

Perhaps my expectations were a little too high.

MWRINCH
07-04-2010, 10:54 PM
I have been using the 310xt for running and biking and I find it very good except when i ran a 16 KM 1,400m elevation gain race today, the watch told me the total distance was only 14.5 KM. I have a hard time believing that the race organizers would be so inaccurate so I have to blame the watch. This is a distance error of 10%. That is a pretty major error if you ask me.

The funny thing that I don't understand is that the bird's eye view route on the web is perfectly accurate so I don't understand why they can not interpolate the actual elevation gain and adjust the total distance from that.

Is there an update coming?

PHILIPSHAMBROOK
07-05-2010, 12:21 AM
I have been using the 310xt for running and biking and I find it very good except when i ran a 16 KM 1,400m elevation gain race today, the watch told me the total distance was only 14.5 KM. I have a hard time believing that the race organizers would be so inaccurate so I have to blame the watch. This is a distance error of 10%. That is a pretty major error if you ask me.

The funny thing that I don't understand is that the bird's eye view route on the web is perfectly accurate so I don't understand why they can not interpolate the actual elevation gain and adjust the total distance from that.

Is there an update coming?

Check it with someone else or by some other means. Race organisers are not infallible.

EKUTTER
07-05-2010, 06:59 AM
Check it with someone else or by some other means. Race organisers are not infallible.

Correct. How did they measure the course? I have known race organizers to be off by more than 10% on totally flat 3 mile courses and swear up and down they measured it. A route with 1400m of climbing would likely be hard to measure. But this is also a rare case where vertical distance maybe have a significant effect on actual distance.

DW152
07-05-2010, 08:39 AM
I have been using the 310xt for running and biking and I find it very good except when i ran a 16 KM 1,400m elevation gain race today, the watch told me the total distance was only 14.5 KM. I have a hard time believing that the race organizers would be so inaccurate so I have to blame the watch. This is a distance error of 10%. That is a pretty major error if you ask me.

The funny thing that I don't understand is that the bird's eye view route on the web is perfectly accurate so I don't understand why they can not interpolate the actual elevation gain and adjust the total distance from that.



Even adding in the vertical elevation in your case won't make much of a difference. 1,400 meter gain over 14,500 meters horizontal distance gives a total actual distance of 14,567 meters.

Was the 16km course certified by a running organization (not a club, but a governing organization)? If so, then I would be inclined to believe that it is actually 16km (although that is a non-standard distance). If not, then I would be suspicious. And if it's a trail race, then I would be really suspicious.

RUNGIRL3K
01-23-2011, 08:56 PM
Mine is having significant issues too. Today my house moved down 72 feet while I was out on a run. I knew it was having issues when I had been running up a steep hill for good while and looked at %grade and it said -1%. I am new to this GPS thing and really looking at the altitude to make sure that I am ready for a hilly race coming up. Should it be the same satellites tracking you out and back? Shouldn't those at least look like mirror images.

As for the 16k race. It is probably a combination of a few things. You are supposed to measure a course down the middle so if you run tangents then you can cut off a good bit. Measuring a course is harder then you would think (especially if the footing is not flat for the wheel or the wheel can dig into something like gravel). Along with those too the GPS could be a little short.

DW152
01-24-2011, 05:42 PM
Should it be the same satellites tracking you out and back? Shouldn't those at least look like mirror images.

The satellites don't track you. Your GPS receives the signal from multiple satellites, and these are constantly moving in and out of coverage.

Yes, your elevation should look like a mirror image. However, the Forerunner uses GPS to measure elevation, and this is not the most accurate method. Turn on elevation correction in Garmin Connect and it will improve the quality a bit.

KRYETMAN
11-11-2011, 05:41 PM
I too have noticed a significant miss with the 310xt's elevation data. Surprisingly, my 305's (I've owned 2 of them) seemed to do a considerably better job on elevation data.

Here's an example that appears to be typical:

This is the elevation profile of a hill repeats workout I frequently do as seen by the 305:

http://i272.photobucket.com/albums/jj192/ftkry/hillrepeats_305.jpg

This is the elevation profile of the same hill repeats workout as seen by the 310xt:

http://i272.photobucket.com/albums/jj192/ftkry/hillrepeats_310xt.jpg

For comparison I mapped the workout on USATF.org's website with the elevation profile shown:

http://i272.photobucket.com/albums/jj192/ftkry/hillrepeats_usatf.jpg

To me it almost looks like the 305's did a FAR BETTER job with the elevation data. it might not have been perfect, but the 310xt seems like their algorithm for the elevation is to use a random number generator. :confused: