Garmin 405 - 4323 kcal during the bike ride my a**
Posted Dec 23 2008 9:13pm
This weekend I did a long bike around the lake Nockamixon - it is the race venue for my 2 races this year (the Steelman and EnduraSport Half Iron ). It is a great 18.5 mile loop around the lake on rolling hills with two fairly good hills - one pretty steep and one fairly long. So it is a great place to ride and train for the terrain common in PA.
On this ride I took my Suunto T6 to monitor my HR, Polar S625X was strapped on the bike as a power meter and just for fun I threw the Garmin 405 in my pocket to get a GPS record of the ride. All went well and the ride was quite nice. I got it done before the huge heat wave came in. I had to re-fuel quite a bit. I may have made a mistake (again) of not taking salt tablets during the ride. But that is not why I'm writing this - the main reason is that as I use the Garmin 405 more and more I found another two major issues new users may need to worry about. I already wrote about the one issue with the elevation data that is just messed-up even on shorter runs or bike rides. But this weekend dring the ride I came across another issue related to energy consumption on the bike. I switched the 405 to bike mode, but even with that setting the darn thing thought I consumed 4323 kcals during the ride. Well not so - according to the Suunto log it is more like 1550 kcal which sounds more accurate. I'm seriously questioning the method Garmin uses to calculate calories. I like the Polar approach better - no HR = no calories information. Better than bad guess in my opinion. Difference between 4300 and 1500 is just too great to be useful.
Second new issue is related to software - Garmin Connect web site where the ride is reported as aerage speed of 11.5mph. Well the math just does not add up on this one - no matter how you slice it riding 56mi in 2:45 is more close to 20mph than to 11.5. Looks like they took the last lap average speed instead of averaging the speed over the entire distance. I hope they can fix this one quickly. The calory consumption issue shows up in the watch so Garmin you really need to release a fix the elevation data and the estimate of calories for biking. I do not burn 77 kcals per mile on the bike. It may be best not to estimate calories expenditure if there is no HR data provided. But that is just my uneducated opinion.