Elevation Correction WAY off sometimes

The F305 does not have a barometric altimeter. GPS for elevation changes is not at all accurate, especially when compared to the 705. Just make sure you have a good satellite lock before you start your ride. Verify that you have the latest software and firmware on your device. Try clearing the satellite cache so that your device will reacquire satellites. To do this, with the unit off hold down the down button while powering on the unit.

As SEILOGRAMP noted, the Forerunners do not have a barometric altimeter and use GPS to calculate altitude. However, in my experience, no amount of updating software or getting a good satellite lock has ever fixed the inaccurate altitude that GPS provides.

Garmin did implement altitude correction on Garmin Connect a couple of months ago. Some people reported good results with it, but on both my Forerunners, even with altitude correction the altitude data are worthless. I still get a lot of variation when running on the same course, and I've gotten completely unbelievable numbers, such as significant altitude gains while running on the beach.

As SEILOGRAMP noted, the Forerunners do not have a barometric altimeter and use GPS to calculate altitude. However, in my experience, no amount of updating software or getting a good satellite lock has ever fixed the inaccurate altitude that GPS provides.

It won't fix it, but there is a chance it might make it better, or at least as good as it can get, given GPS limitations. Not having a good satellite lock will only make matters worse.

Thanks for the replies, but I don't think I explained my issue clearly enough...

The problem I'm having is with elevation corrections implemented on Garmin Connect. I know my forerunner is not going to be very accurate for elevation. The problem is that on certain rides when I enable elevation corrections in Garmin Connect the elevation gains and losses go crazy.
I actually found another example of it tonight.

I did this ride a couple weeks ago. GC reports 405m of gain and 952 m of losses with elevation corrections enabled. These numbers sound about right judging from topo maps.
http://connect.garmin.com/activity/43330403

About a week later I did the exact same ride again:
http://connect.garmin.com/activity/44574901

This time GC reports 2144m of climbing and 2688 m of loss. That is ludicrous. If I disable elevation corrections on that ride I get 627m up and 1165m down. Not particularly accurate, but at least not completely out to lunch. Surely something strange is going on with the website here. I don't understand how the elevation corrections feature could make the data less accurate by a factor of 4 or 5.

I should point out that the typical accuracy I see while riding is usually about 4-7 metres. I don't have much experience with other units, but that seems reasonable to me for riding in trees in the mountains.

So no one else has this issue?

Elevation gain is way off

I have the same problem I was kayak racing on the ocean and the 310xt said I made an elevation gain of 350meters !!!

Is that with Elevation Corrections on or off in Garmin Connect?


I actually just noticed the other day that this problem started for me when I bought a cadence sensor.

Same in Singapore

Cycling with Edge 500 coupled with HR & Cadence sensors

Initial numbers on GC:

Elevation Gain: 61m
Elevation Loss: 87m
Min Elevation: 21m
Max Elevation: 66m

After corrections enabled:

Elevation Gain: 108m (+47m)
Elevation Loss: 111m (+24m)
Min Elevation: 2m (-19m)
Max Elevation: 44m (-22m)

Pretty significant!

For me I seemed to fix the problem by removing the wheel speed magnet from the bike. I don't really see a need to have it anyway since I never ride that bike indoors. Once I took that magnet off it seemed to work normally again.