Garmin/Training Peaks/ Strava power differences
Mine is consistently 10-15% off e.g. a near 3hr ride at the weekend produced a 204 watts NP and 161 average on Garmin and Training peaks. However when loaded into strava, its 182 weighted and 159 average. From first glance, a completely different ride. It would appear I road steady according to strava, but in reality it was tempo.
I suspect that everyone is the same as Strava don't appear to use the same maths as Garmin. This is worth taking into account if anyone is using Strava to analyse there power data. Its quite a bit off so should be taken with a pinch of salt. Especially if you are using anything like TSS or intensity factors.
use something like TP's or Golden cheetah (free) if you want real analysis.