surgeonstone

When I upload my gamin into a variety of web programs ( ridewithgps),
I get the usual data but I noticed that on the ridewithgps it gives an average power in watts for the ride. Now I do not have the power tap and so this must be coming from speed, heart-rate etc. How accurate is this info? Todays ride was an average of 250 watts.

mvnsnd

I would say it's optimistic. I don't have a power meter either, but uploaded a trainer ride from a KK trainer. The ridewithgps number was higher than the KK number based on average speed. I already thought the KK numbers were supposed to be a little high.

surgeonstone

That was my thought as well.

psuaero

Should be easy to see... if I get time in a little bit I'll pick one of my rides or a portion of a ride and upload it to ridewithgps. I'll post results.

Done...

It's pretty optimistic. I put in a fairly hard effort 28 mile ride from March. RidewithGPS says 299W (me likey)... TrainingPeaks Powertap combo says 199W (normalized 233W).

Here are the rest of the stats from both:
RidewithGPS.com
Departed: Mar 08, '11, 11:58AM
Starts in: Elkridge, MD 21075, US
Distance: 27.8 mi
Selection Distance: 27.8 mi
Elevation: + 1722 / - 1713 ft
Max Grade: 13.2 %
Avg. Grade: 0.6 %
Total Duration: 01:34:12
Selection Duration: 01:34:12
Moving Time: 01:31:28
Selection Moving Time: 01:31:35
Stopped Time: 00:02:37
Calories burned: 1690
Avg Watts: 299
Max Speed: 43.1 mph
Average Speed: 18.1 mph
Max Heartrate: 192 bpm
Min Heartrate: 94 bpm
Average Heartrate: 164 bpm

TrainingPeaks
Entire workout (190 watts):
Duration: 1:32:25 (1:35:52)
Work: 1044 kJ
TSS: 201 (intensity factor 1.164)
Norm Power: 233
VI: 1.22
Pw:HR: 2.08%
Pa:HR: 4.52%
Distance: 27.99 mi
Min Max Avg
Power: 0 686 190 watts
Heart Rate: 91 192 165 bpm
Cadence: 32 209 85 rpm
Speed: 0 36.8 18.2 mph

PS: The small difference in ride times are probably due to the GPS data coming from my Garmin Edge 500 and the Power data coming from my wired PowerTap. If anyone things it makes a huge difference I can go back and fine tune the data and re-import into RidewithGPS but I don't think it will make more than a couple watts difference.

LowCel 

According to power calculators I've used I'm a god. According to my power meter I suck. Unfortunately I think my power meter is right.

colombo357

Fabian Cancellara won Tour of Flanders last year with an average of 285 watts.

https://www.youtube.com/watch?v=s_OXoBbKv5c

psuaero's data shows an overestimate of 50%, which seems about right.

psuaero

Riding with a group or peleton has very different affect on power. All the coasting and drafting lowers it significantly.

Yesterday I hit the local Saturday morning ride. I hung on to the faster guys for ~30 miles and managed to more or less stay with the lead 7-8 (started with 20+) from beginning to end. At times I was right with them and not pedalling while being sucked along in the draft. At other times (when they turned on the gas) I was yo-yo'ing off the back putting in a TT like effort just to keep them in sight.

I averaged 180W over the entire 28 miles (19.4mph). The middle hour was 19.93 miles, 193W average, and 19.9mph, with an ave. HR was 179bpm which is pretty much my threshold.

surgeonstone

Thanks, that helps. What is the difference between the combo (199 w) and the normalized (233 w).

surgeonstone

Shoot- that means it's not too late for me to join the pro circuit. Wait, I'm 57, maybe...just maybe...nnaaaah.

psuaero

I was going to cut-and-paste the definition in there but it's pretty long. The basic short answer is that 199W is my average including all the light pedaling, coasting (power rolls off to zero in a sample or two), etc. Normalized power is more like if I was to hammer on a flat ride all by my lonesome in the wind. It takes other physiological response into account which is why it's higher.

merlinextraligh

that doesn't tell you much. My typical race file is often over 285 watts average power, admittedly for shorter races than the Ronde.

In a 7 hour race, lots of time Sparticus would be tucked in the pack and not working har, particularly before the decisive climbs.

Add in that I'm heavier and less aero, and its not surprising that my averag pwoer is higher for a race.

The interesting data would be Cancellara's peak power in w/kg for 1 minute, 5 minutes, and 20 minutes from a classic. Those are the numbers where you would see a big difference.

surgeonstone

That would be my ride today, 20 miles at 13 mph into a 30+ mph headwind. Sucked the life right out of me but the return was sweet.