12 April 2010

Garmin & Me: The Adventure Begins

Yep, I'm now one of those smarmy Garmin owners.

Which is great. 'Cos I can now bore you to death with stuff like this:

And this:

And this:

The possibilities are mind boggling. As are the questions. Two that have come to mind for me so far are (and I'm just copying these straight from posts I have put on Rotorburn):

Yes - I know that Polar have the better (patented) algorithm for calculating calories burnt than Garmin etc etc. I know that comparing numbers between devices isn't going to be accurate, etc etc.

My question is - has anyone worked out a rough 'conversion factor' between the two?

The reason I ask - I've just bought a Edge 705 and gave it a test run this morning on the road. In my training diary, I track 'intensity' - pretty much calories burned divided by length of ride. This gives me a rough indication of how hard I was working. With 3 years worth of Polar data, this roughly works out to 40 - 50 kJ / min for road ride, 50 - 60 for quicker road ride, 55 - 65 on the MTB, and anything up to about 80 for a lactic XC sufferfest. (I convert Calories to kJ for my tracking)

Plugged my first Garmin data this morning into the sheet. What was a pretty relaxed ride (would have expected about 45kJ / min) came back as 93kJ / min. Obviously a bit of different between the data for the two!

I'm thinking I'm going to have to wear the Polar AND the Garmin for a few rides to see if I can't work out what the difference is between the two - unless someone has already crunched the numbers?


Well, interestingly enough, I ran the Garmin today for the Wagga 3+3, which gives me useful comparison data to last years race.

Intensity for last year (measured with Polar) was 71kJ/min. Intensity this year (measured with Garmin) was 63kJ/min. This year I'm about 5kg lighter, and was lapping around 4 minutes quicker, I'd expect intensity to be a little lower. So maybe the gap between the two devices is not that great?

One thought that did occur to me. Polar (at least mine, watch style F6) doesn't take into account bike / equipment weight, where Garmin does. This does mean it's important to make sure when I'm switching it between bikes, I change the bike profile (also to keep odometers correct). Maybe the reason the road ride's result was so far out the window was because I hadn't changed the profile, and it thought I was doing 50km/h on a 13kg duallie.

Anyway, still learning. It certainly looks like going close to being the killer device though!

So, sit down, settle in, and prepare to be amused as I struggle with the complexities of this new toy.

One good thing I've found though - public domain contour and street maps to upload. Check out Shonkymaps and Contours Australia if you're interested.

1 comment:

Grimzentide said...

I love looking at all this kind of data and the latest update to Garmin Connect is pretty awesome.