I know the strava calculated Watts output figures are not the most accurate but anyone shine any light on this:
Two of us rode the same road segment on Sunday separately, both similar age and height but he is 10-15kgs heavier than me.
We completed the segment with one second difference, segment is uphill and about 400m long. I got KOM he was second so neither of us were hanging around. Both using Garmin 800/810. Average heart rate was 1 beat different for us both.
My calculated power output 615 watts, my mates 375 watts. How can the two be so different???
One of you has entered your weight incorrectly in your profile?
your cadence was different?
As he is carrying more weight. The weight of the bike also counts.
are both bike and personal info correct for both of you?
check the height gained.
strava/garmin combo quite often gives mad height gained.
I'm guessing bike weight? Presumably Strava makes an allowance for rolling resistance and worse aerodynamics on an MTB by using a different formula for heavy bikes rather than light ones?
Also Strava gives you the option after a ride to 'correct' the elevation profile by superimposing your route onto it's maps. If it's map is wrong or your data wobbles up and down the hill a bit then it could knock either out. I'm more inclined to believe my Garmin than the websites elevation based on my old 305 always agreeing with the OS map to within +/- 2% or so, and mapmyride and the like consistently being 50% lower.
your cadence was different?
Power/cadence aren't related unless you're doing quadrant analysis.
I would tend to ignore the Wattage estimates and just compare the directly measured variables. Did you both have cadence sensors?
Stick the segment url in http://raceshape.com/ and have look at the altitude profile for you and your mate.