Why am I getting different data on Garmin Connect vs. GTC?

[berkeley]

OK, I just got a Garmin 305. When I upload to Garmin Connect, I get one set of numbers. When I upload the same ride to the Garmin Training Software, I get different ones - particularly when it comes to total climbing. And it's not even close.

For instance, here are the totals for today's ride according to the GTC:
Elevation Gain: 4.107 ft
Elevation Loss: 3,679 ft

And Garmin Connect:
Elevation Gain: 2,444 ft
Elevation Loss: 2,132 ft

Other times, my average speed changes between the two, though it didn't this ride.

Am I doing something wrong? :confused:

[SadieKate]

Do a search on Motionbased and on Sporttracks. You can read about it to your hearts content. I haven't heard that Garmin Connect is any better and I won't waste my time testing it when there are better ways.

http://forums.teamestrogen.com/showthread.php?t=27852&highlight=sporttracks

PS - "Search" is your friend.:)

[berkeley]

Do a search on Motionbased and on Sporttracks. You can read about it to your hearts content. I haven't heard that Garmin Connect is any better and I won't waste my time testing it when there are better ways.

http://forums.teamestrogen.com/showthread.php?t=27852&highlight=sporttracks

PS - "Search" is your friend.:)

Why would I think to search on software I'm not using? :confused:

I did search for any related Garmin Connect issues, and found nothing.

Thanks for the link though, I'll give it a read. :)

[SadieKate]

Why would I think to search on software I'm not using? :confused:How about Garmin and elevation? Get creative. You'll find loads of discussion.

[berkeley]

But none with issues specifically with using Garmin Connect - which was my question. Do I need to use some sort of correction with Garmin Connect? Or is it GTC that needs correction? Which one is causing the problem, I have no idea, and I can't extrapolate that from the ST or MB discussions. Perhaps the solution is to ditch both. :rolleyes:

I can find the discussions on other programs (I'm not a total dolt). I do appreciate the tutorial on searching though. :p

[gnat23]

ALL the programs seem take the raw data (GPS coordinates/altitude) and interpret it differently with different sensitivity, as far as I can tell.

Just pick one software and stick to it for consistency.

-- gnat!

[Mr. Bloom]

Hey Berkeley. This has been submitted to ongoing debate. Other search words would include "MotionBased", "Barometric"

There are a couple of posts out there that I've participated in:
http://forums.teamestrogen.com/showthread.php?t=29926&highlight=garmin+elevation
http://forums.teamestrogen.com/showthread.php?t=27385&highlight=garmin+elevation
http://forums.teamestrogen.com/showthread.php?t=27852&highlight=barometric

There are other posts that I've partcipated in that I am unable to find myself even though I remember partcipating in them.

Suffice it to say that this continues to be an interest for me as I often do hilly rides...although others are fatigued by the issue...

Yes, I do use the Correction Feature in Motion Based and I (although others debate it) find it to be useful and accurate. I've tested the result against some of the online mapping software and find it to be reasonable accurate.

[berkeley]

Interesting. Thanks.

So here's maillotoplis' quote from one of those threads "It's not really a Garmin issue, because the barometric adjusted Garmin data run through Garmin training center is pretty spot on - consistent with my old HAC4 data for the same rides and with other people's Polars, etc. "

But my GTC numbers seemed WAY off - so yeah, I'm confused.

So, not wanting to rehash this clearly long-running debate, has anyone found that the Garmin Connect is particularly problematic? From what I can tell, it's more accurate than the GTC, but that's a guess on what I thought I did yesterday. It seems that others have found GTC to be accurate, but I can't seem to find anyone using garmin connect or commenting on the elevation accuracy.

My 305 is the Edge, if that makes any difference.

Off to google again...

[TrekTheKaty]

There was a discussion here last summer about the accuracy of elevation on a Garmin 305. The consensus was the elevation is inaccurate with this device--I forget why. However, if the numbers looks impressive--I say they are correct :D

I use a Garmin 305 with MotionBased. I have a Mac and could only use the Garmin software when it was updated recently. I downloaded some old rides and the numbers were slightly different. When I compare distance and speed with two other riders using different brands of bike computers--it is very accurate.

Motionbased does have a very active and informative forum--it was purchased by Garmin.

[OakLeaf]

My 305 is the Edge, if that makes any difference.

Yes, it does, actually.

The Edge 305 has a barometric altimeter. The Forerunner series, including the Forerunner 305, does not.

[SadieKate]

Some searches from the world wide web:
http://forums.bicycling.com/eve/forums/a/tpc/f/612104717/m/3731042216

http://cyclingexperiences.com/2009/03/05/garmin-connect-update-0302/

Examples with a non-barometric device
http://gpsrunner.blogspot.com/2009/06/gps-elevation-data-error-and-correction.html
http://getsatisfaction.com/garmin/topics/the_data_doesnt_match

Quote from Garmin at some point in time (Iforget when):
Garmin Connect is using a different methodology to smooth elevation gain/loss compared to MotionBased. As a result, especially for Forerunner devices, the elevation gain/loss numbers will be inflated. We are still working on our smoothing algorithm and intend to run this across all activities at Garmin Connect in the future to more accurately reflect the actual gain/loss.
Garmin Connect does not support weather at this time. We plan on introducing this feature at Garmin Connect. When we do, it will run against all past, present, and future activities at Garmin Connect.

I lurves me Sporttracks (http://www.zonefivesoftware.com/SportTracks/).