Yesterday I was doing some comparisons between an older wired SRM and a Garmin/Powertap. I switched from the SRM to the PT this year, and I wanted to see how accurate they were to each other. I noticed a couple interesting things.
1) SRM has no data averaging, but the readings were far more stable and directly reflected effort level (with no delay)
2) Powertap on 3s averaging still jumped up and down ~10 watts every second
3) Despite this, power was within 1 or 2 watts after warmup and re-calibration—especially above 200 watts
The quality of the data coming from the SRM is dramatically better. When I used the SRM's display to regulate my effort instead of the Powertap, it was much easier to maintain. You could also see this when viewing the graph after the fact—it was much smoother when I was looking at that instead of the Garmin or TrainerRoad.
I know they're different technologies, but since the ultimate power data is the same, this suggests that this is something that could be controlled by software. For a Powertap to display power the same way, it might be possible to calculate it. Instead of a running average, using past data (or assumed data), there could be a way to have a data display that's actually readable and useable, without having to resort to 3s (or unfortunately even higher) data averaging.
I read somewhere that the Joule computers have more stable displays with better data averaging, but nobody expanded on it any further. Has anyone done any comparisons between the Garmin-calculated data display and a Joule computer?
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George Dedopoulos | @geodee | geodee.com | Team Atomica | Toronto Triathlon Club
1) SRM has no data averaging, but the readings were far more stable and directly reflected effort level (with no delay)
2) Powertap on 3s averaging still jumped up and down ~10 watts every second
3) Despite this, power was within 1 or 2 watts after warmup and re-calibration—especially above 200 watts
The quality of the data coming from the SRM is dramatically better. When I used the SRM's display to regulate my effort instead of the Powertap, it was much easier to maintain. You could also see this when viewing the graph after the fact—it was much smoother when I was looking at that instead of the Garmin or TrainerRoad.
I know they're different technologies, but since the ultimate power data is the same, this suggests that this is something that could be controlled by software. For a Powertap to display power the same way, it might be possible to calculate it. Instead of a running average, using past data (or assumed data), there could be a way to have a data display that's actually readable and useable, without having to resort to 3s (or unfortunately even higher) data averaging.
I read somewhere that the Joule computers have more stable displays with better data averaging, but nobody expanded on it any further. Has anyone done any comparisons between the Garmin-calculated data display and a Joule computer?
_____________________________________________________
George Dedopoulos | @geodee | geodee.com | Team Atomica | Toronto Triathlon Club