Hoping someone can can offer some explanation to this…
It’s only become apparent to me this year and it’s only really obvious in races, but Garmin Connect seems to calculate average power differently to everyone else, despite it all coming from the same source (fit file?)
So today’s race was recorded by my Edge 530 and initially uploaded to Garmin Connect:
Garmin Connect = 236w average power
Strava = 225w
Trainerroad = 225w
Intervals.icu = 225w
I could handle 1 or 2 watts, which is generally the case in other rides, but for races there are these large differences.
Anyone know why or notice the same on their rides/races data?
Surely average power is a standard formula with no variables such as FTP, body weight etc.
it was a road race so in theory it shouldn’t even be one second out.
But i think drop outs is the most logical explanation and i can only assume that Strava/Trainerroad/Intervals.icu etc all count these these as zero whereas Garmin look to exclude them or maybe fill with a 30 sec rolling average. So is Garmin actually the more accurate, despite being in the minority?? I’m just struggling to find anything online to support this.
As mentioned, it’s only obvious in races, so i’m thinking with 60+ other riders also using ant+/bluetooth connections is why there is the increase in drop outs…
According to this thread on the garmin forums: https://forums.garmin.com/sports-fitness/cycling/f/edge-1030-plus/258340/incorrect-average-lap-power : The power meter sends accumulated work (kJ) data in addition to the power readings (Watt) for each record it sends. So in case the headunit misses some records, it can use the accumulated work to still calculate average power correctly. Apparently the headunit and garmin connect use this data for that purpose, while strava, trainerroad, and many other tools do not. In summary: the data Garmin gives on the headunit and in garmin connect is more accurate.
I may try to switch to bluetooth (now using ANT+), because I think in theory bluetooth should be less susceptible to dropouts.
I agree. It all has to do with dropouts and Garmin does a really good job at filling out all the possible data fields of a fit file, while other companies dont. This is part of the reason why garmin fit files are bigger. Garmin fills in alot of summary entries (activity, session, lap). So in GC they just read these headers to display your summary data. Because other sites like strava have to process fit files from many headunits, they have to process the actual 1sec data entries to compute the summary data instead of using the summary entries because some don’t put data in them. I actually prefer the strava method as it’s a good indicator that dropouts are occurring.
Get Faster with TrainerRoad
Sign up and download the app to start training. Available on iOS, Android, Windows and Mac devices.
Ask a Cycling Coach Podcast
This is the only podcast dedicated to making you a faster cyclist. Listen to the latest episode and more.
We Are Here to Help!
Browse hundreds of articles in our Support Center or contact our world-class support team to get back on track.