Garmin Training Centre and Sportracks readings .....

[Slowbee]

Yes I know they are both very different programs. Currently I am using a 705 edge with cadence and speed sensor

 

I have been using Sportstrack for a while now, but decided to give GTC a try.

 

The first thing I noted was the different readings. As an example, in sportstrack my avg. cadence is 63, while in GTC it is 71. The calories, avg speed, heart rate etc are all different.

 

Anyone have any idea as to why this may be so.

 

The garmin threads have lots of comment about how the 705 calculates speed if you have the speed sensor (vs GPS only).

 

Is it possible the one program is picking up different data (although the cadence can only come from the cadence sensor).

 

Any idea's?

[Tiny K]

Sportstracks could be reading the total revolutions and dividing it over the time whereas GTC could be taking the actual reading and where there are zero's, treating them as such.

 

The Garmin also picks up moving and non-moving time whereas ST is most likely not reading that - it is just taking total time. I know mapmyride is like that. So if I upload my ride onto mmr just for the route, I need to correct the ride to to Garmin's moving time and not the total time read by mmr.

 

For some reason, GTC doesn't want to work on my laptop. so I upload my files the Garmin Connect site.

 

Edit: typo

Edited January 12, 2012 by Tiny K

[Slowbee]

So you saying that GTC is more accurate with its data ?

[Thug]

I don't understand how theoretically they can be different as the information source for both is one and the same file, be it .gpx or .fit.

 

My figures between the 2 programs as far as I'm aware are the same.

Edited January 12, 2012 by Thug

[Minion]

It depends what you're looking for. I personally think the Sporttracks method is more accurate: I want a record of every single second of my training. Just because I'm stopped at a traffic light, doesn't mean it's not having some effect (in this case recovery).

[Slowbee]

I don't understand how theoretically they can be different as the information source for both is one and the same file, be it .gpx or .fit.

 

My figures between the 2 programs as far as I'm aware are the same.

 

That is what I was thinking, from the same source - but I checked, both programs give different results

[walkerr]

FWIW - I use GTC and the online Garmin Connect and FitTrack forums. And there is often slight differences in the numbers. My only conclusion so far is all of them have to "average out" a mass of individual GPS log points, and possible some also discard or smooth out any bad ones. Given that, I'd guess each possibly has their own approach/algorithm for averaging and smoothing the raw data.

 

But I could be wrong .... I usually am ....

[riaanb]

That is what I was thinking, from the same source - but I checked, both programs give different results

 

I think it's like what Tiny K was saying. Take cadence for example - Garmin has a setting to ignore or include zeros in the average. You might not be stopped, but you could be free-wheeling, so the averages are different depending on the different settings.

Edited January 13, 2012 by riaanb

[Tiny K]

So you saying that GTC is more accurate with its data ?

 

I would think so - when I download my data I get actual time and moving time. So if I stop at a traffic light, the time continues running but my moving time stops i.e. I get an accurate average speed and average cadence.

 

Here is an example - http://connect.garmin.com/activity/138557049 , vs, http://www.mapmyride.com/routes/view/62780776

 

Strangely enough, the elevation data is different even with Garmin elevation correction...... I can't compare that to sportstracks as I have never used it.

[Minion]

 

I would think so - when I download my data I get actual time and moving time. So if I stop at a traffic light, the time continues running but my moving time stops i.e. I get an accurate average speed and average cadence.

I think it might also relate to whether or not you use auto-pause on the device. I don't use it - I feel my Garmin should be tracking every second of my ride - and I get the same average values in GC, Mapmyride and ST:

 

 

 

 

What's interesting is the distance value. The true distance is closer to 39.4km. I deliberately set the wheel size for my GSC10 sensor about 15% smaller. This shows that the speed sensor takes precedence over GPS values when calculating speed and distance.

 

If you tell Sporttracks to calculate the values, it uses the GPS track to give the true speed and distance:

 

This can be useful to determine whether your wheel size is correct.

 

PS. I can't see your Mapmyride file - its security setting is set to private.

Edited January 13, 2012 by Edman

[Tiny K]

I think it might also relate to whether or not you use auto-pause on the device. I don't use it - I feel my Garmin should be tracking every second of my ride - and I get the same average values in GC, Mapmyride and ST:

 

 

 

What's interesting is the distance value. The true distance is closer to 39.4km. I deliberately set the wheel size for my GSC10 sensor about 15% smaller. This shows that the speed sensor take precedence over GPS values when calculating speed and distance.

 

If you tell Sporttracks to calculate the values, it uses the GPS track to give the true speed and distance:

 

 

This can be useful to determine whether your wheel size is correct.

 

PS. I can't see your Mapmyride file - its security setting is set to private.

 

Yip, mine is set with auto pause off too, so I get moving time and elapsed time. It helps that way if I, for eg, do a Franschoek ride and stop for coffee (which turns to breakfast) and stop for almost an hour. I leave the garmin running knowing that once I finish, I can see the moving ride time and average speed relative to the time I was actually on the bike.

 

Also, I don't use the speed sensor. The GPS functions well enough on it's own. Just click on elevation correction once uploaded - changes due to barometric pressure changes on the ride - can cause inaccuracies without speed sensor.

 

Lemmie go look at that setting quickly.....

[Slowbee]

I think it's like what Tiny K was saying. Take cadence for example - Garmin has a setting to ignore or include zeros in the average. You might not be stopped, but you could be free-wheeling, so the averages are different depending on the different settings.

 

how would the two software packages know the difference ?

 

I uploaded the same set of data without changing anything. ST had 63 as opposed to 71 on GTC

[Tiny K]

how would the two software packages know the difference ?

 

I uploaded the same set of data without changing anything. ST had 63 as opposed to 71 on GTC

 

Not got a clue Slowbee! Maybe ST does not read the zero's but GTC does. Does ST give you a cadence profile at all?

[nochain]

Have you guys tried Strava.com?

 

If you train with a Garmin, iPhone or Android device it is brilliant!!

 

You can download your files and then compare your times on segments of your route (for example a specific climb) that other riders have done before. So it shows you how many other riders have done that climb and how you rate. You can also create your own segment and compete against your previous efforts and if anybody then rides that segment it will show you their result.

 

If you ride Groenkloof for instance most of those single track sections are segments and you can then see how you fare against others riders and your previous rides.

 

It also has a social component to it, you can follow friends and pro's to see what they are up to.

[SwissVan]

how would the two software packages know the difference ?

 

I uploaded the same set of data without changing anything. ST had 63 as opposed to 71 on GTC

 

That sucks, how difficult can it be for something like a garmin gps and related software to accurately record cadence?

BTW both figures 63 and 71 look a bit low, either your cruising the beach roads or both have got the cadence wrong.

Borrow a polar CS 400 and double check those cadence recordings.....

[Minion]

how would the two software packages know the difference ?

 

I uploaded the same set of data without changing anything. ST had 63 as opposed to 71 on GTC

Have you tried uploading the data to Garmin Connect? GTC is not the most well-regarded of software packages.