Robert Dempster

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*** Welcome to my PMB blog, the sixty ninth! ***
Satellite Tracked Cycling Stats
More hit than miss?
26 September 2017

Being able to track ones ride while out cycling using a satellite tracking enabled device such as a custom sports watch, a cell phone or a custom device fitted to the bike is not only great fun, it also provides useful statistics to anyone wishing to monitor and improve their perfomance. Since installing Sports Tracker on my then Nokia N8 back in October 2012 I have clocked up more than 12500 kilometers. I said, "more than" because some kilometer were lost either because of mistakes I made, or because of failings on the part of Sports Tracker or the cell phone it was running on at the time.

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Right from the outset I have been and continue to be impressed by the huge accomplishment associated with what is achieved in terms of satellite tracking by the Sports Tracker app running on a cell phone. Of course it does not stop there as it can now also be achieved by wearing a Sports Watch. At the same time I have also been intrigued by the manner in which the accuracy of the satellite tracking recording process is affected by factors such as the terrain through which the cyclist cycles, the surroundings i.e., tall trees, tall buildings, surrounding hills and mountains and of course the weather.

Generally it would seem that the route followed is recorded fairly accurately to the extent that it may be obvious that a rider rode up on side of a road and returned riding on the other side of the rode. What the system does seem to struggle with is altitude and this is immediately noticeable in terms of the starting and ending elevations for a ride that started and terminated in the same place is not necessarily the same. It then follows that the ascent and descent will also not be the same for such a ride. It is also true that there are differences between what is recorde by different devices and I would guess that this is to be expected given that these are not high spec devices.

What I would not expect, is that the ascent and descent reported by the TomTom and Strava websites that receive the same data sets from my TomTom Sports watch are different. Two plus Two is Four and that is it. For the ride included in this blog Sports Tracker (using the cell phones' data), TomTom (using the sports watch's data) and Strava (using the watch's data) report an ascent of 673m, 851m, and 678m respectively. How can these results be so different?

Ironically the figures suggest that Strava does a better job with the TomTom watch's data than TomTom does itself. I also don't care too much for the manner in which TomTom presents the ride profile. The elevation is plotted agains time and while it is interesting to see how much more time is spent climbing as compared to descending, I much prefer the symmetrical plot produced by Strava as a result of plotting the elevation against distance. Perhaps this should be optional i.e., either time or distance. As for TomTom using a zero based scale for the elevation, well that in my book is simple "dumb". If anyone thinks otherwise I would love to hear the argument.

Money can't buy happiness, but it can buy a bicycle.

Some links

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Takes a while to load, but then proceeds quite smoothly. Looses image aspect ratio for portrait images i.e., squashes them.

If you have any comments, corrections, suggestions or plain criticism, I would appreciate it if you would communicate the same to me.

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