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Elevation Correction WAY off sometimes

Former Member over 15 years ago

I have a Forerunner 305 that I use strapped to the handlebars on my bike.
Lately I've noticed that every now and then I'll upload a ride to GC and the elevation gains and losses are way off when elevation correction is enabled.

For example I did this ride yesterday:
http://connect.garmin.com/activity/46781019
With elevation corrections disabled I get:

Elevation gain: 1143 m
Elevation loss: 1383 m

With corrections enabled I get:

Elevation gain: 4334 m
Elevation loss: 4558 m

Elevation corrections more than tripled my gains and losses!
Looking at someone else's activity that did the same trail with an Edge 705 the numbers produced without elevation corrections are pretty reasonable. Obviously the corrected numbers are not...
I had a similar problem occur with a different ride a few weeks ago as well.

Is this some sort of bug occuring? Errors with the elevation correction database?

Is there anything I can do to fix this?

0 rfruns over 11 years ago

I experienced this on Sunday. Went out for a ride with E810, I've done the ride before. Comparing to the previous ride; the "shape" of the elevation (too smooth), and the implied elevation of my end (& start) point are wrong. The corrected elevation is wrong from the halfway point, coincidentally when 2 hours of heavy rain started. I can see some in unit measurement could have been thrown, but external map based should not.

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.