Strava Power Zone

skinnydog1973

Hi i was after a bit help what does the power zone analysis on strava mean towards my cycling, i did a 13 mile ride last night average speed 17.8 mph and the power zone said 439kg energy output and 163 average power,im new to all this so are these figures good or what figures should i be aiming for the ride i did was a flat 13 miles cheers for any help

16mm

I'd largely ignore these figures, as they are estimates unless you have a pwoer meter.

schweiz

it said you used 439 kJ (kilojoules) of energy and averaged a power output of 163 W (Watt energy (in J) divided by time (in seconds)

I'll start by saying that Strava power and energy values are not accurate. They are calculated by using the body weight you've entered into Strava, possible the bicycle weight and then average values for rolling resistance, wind resistance and there's probably other factors in their too (such as gradient). On flatish sections, the estimates are often way out, they get closer to real values on steeper climbs 7-8% + where aerodynamic drag becomes less of an issue for us mere mortals

As to what you should be aiming for depends mainly on your weight as what is important in not the raw power value but the power to weight ratio. So if you weigh 60 kg and can sustain 300 W then that is 5 W/kg. An 80 kg rider would have to sustain 400 W (80 x 5) to be able to climb at the same speed.

Unless you are young and/or extremely light then 163W is not particularly high. For reference I weigh 81/82 kg and can sustain a NP of 320 W (measured with a PowerTap hub) but get my ass kicked regularly. The guys beating me are probably generating the same power or less but weigh 10 or more kg less!

hatch87

schweiz wrote:

Unless you are young and/or extremely light then 163W is not particularly high. For reference I weigh 81/82 kg and can sustain a NP of 320 W (measured with a PowerTap hub) but get my ass kicked regularly. The guys beating me are probably generating the same power or less but weigh 10 or more kg less!

My last ride I averaged 116w, I think my best is 145w which gave me a 17.4 mph average over 25 miles. Although thats based on Stravas estimates so I'm hoping I produce double that

slowbike

Ok - just double your reported weight and see the difference ...

roger_merriman

hatch87 wrote:

schweiz wrote:

Unless you are young and/or extremely light then 163W is not particularly high. For reference I weigh 81/82 kg and can sustain a NP of 320 W (measured with a PowerTap hub) but get my ass kicked regularly. The guys beating me are probably generating the same power or less but weigh 10 or more kg less!

My last ride I averaged 116w, I think my best is 145w which gave me a 17.4 mph average over 25 miles. Although thats based on Stravas estimates so I'm hoping I produce double that

Strava guesses 130ish average watts for myself as well, mind you seem to get the same for flat out or pottering...

Grill

hatch87 wrote:

schweiz wrote:

Unless you are young and/or extremely light then 163W is not particularly high. For reference I weigh 81/82 kg and can sustain a NP of 320 W (measured with a PowerTap hub) but get my ass kicked regularly. The guys beating me are probably generating the same power or less but weigh 10 or more kg less!

My last ride I averaged 116w, I think my best is 145w which gave me a 17.4 mph average over 25 miles. Although thats based on Stravas estimates so I'm hoping I produce double that

Without looking at any variables I can safely say that you won't get anywhere near double that and that 146w figure is actually in the realm of what you produce (unless that route is hilly as balls).

schweiz

Grill wrote:

hatch87 wrote:

schweiz wrote:

Unless you are young and/or extremely light then 163W is not particularly high. For reference I weigh 81/82 kg and can sustain a NP of 320 W (measured with a PowerTap hub) but get my ass kicked regularly. The guys beating me are probably generating the same power or less but weigh 10 or more kg less!

My last ride I averaged 116w, I think my best is 145w which gave me a 17.4 mph average over 25 miles. Although thats based on Stravas estimates so I'm hoping I produce double that

Without looking at any variables I can safely say that you won't get anywhere near double that and that 146w figure is actually in the realm of what you produce (unless that route is hilly as balls).

Strava estimates are out, but they're not 100% out. I did half a dozen tests (admittedly not enough to form any reliable statisical analysis!!). Sometimes it was up to 10-15% on flatter routes when there was a strong wind, but sometimes they're surprisingly close to powertap data!

Grill

There's another thread on this somewhere, but my P2M and Strava power overlap so infrequently that it may as well be a random occurrence.

Gruge

Strava seems to make a big deal of the bike weight. I weigh 95kg and have two bikes, one weighs 15kg the other 10kg. The same 15 mile ride flags as 146W on the lighter bike and 278W on the heavier bike. Now that's not my riding it twice; just correcting which bike I did it on.

If it's based on the combined weight of bike and person then there should be comparitively little difference.

PhunkyPhil

I ink like most information on Strava it should've ignored as its just them guessing information.

For them to display power output on the leader boards is pointless as comparing the power of a 140lb rider against a 200lb is meaningless. They should be displaying the power to weight ratio because if both riders did the same speed on a section they can't be generating the same power as the heavier chap must be using ore watts.

You may also notice if you look at your best times for a section that on the same bike your slower times sometimes have a much higher power output. It's doesn't make sense if they don't know the actual wind speed and direction for the section. If you are going slower you are generating less power.