tallmantim

Went out on a regular ride yesterday to try out my new PowerTap Elite.

Quite happy with it so far, although I need a little more work on getting used to the new computer - plus not sure of the reliability of the virtual cadence calculator.

Here are the stats through from the ride.


Time Ave Watts Watts/kg Ride/Time offset

5 sec 1,103 11.31 02:57:06
30 sec 668 6.85 01:36:11
1 min 552 5.66 01:36:10
2 min 447 4.58 01:54:47
3 min 434 4.45 01:04:13
4 min 425 4.36 01:04:16
5 min 417 4.28 01:04:16
10 min 383 3.93 02:00:46
15 min 378 3.88 01:54:15
20 min 363 3.72 00:54:03
30 min 351 3.6 00:48:15
40 min 328 3.36 00:41:07
60 min 310 3.18 0002
90 min 293 3 00:22:57
120 min 273 2.8 00:10:21



Average Power, Watts 245
Maximum Power, Watts 1,354
Normalized Power 316
Average Watts/kg 2.5
Maximum Watts/kg 13.9




Total Elapsed Time 02:58:59
Distance, km 65.85
Work, kJ 3058
Temperature, °C --
Average Power, Watts 245
Average Cadence 63
Average Speed, kph 27.2
Average Heart Rate --
Ride Time (Time Moving) 02:54:47
Weight, kg 97.5
VAM --

lazerzxr

How come the average speed doesnt work out? 65.85km in 2:55 is'nt 27.2 average? Just wondering

tallmantim

I think it includes periods of 0kmh while the computer is turned on...

rollin

I like that it's post's a when it thinks you were riding like an old man!

BostonBullit

I sat the PT computer on my handlebar next to my Garmin 305 w/cadence sensor on the trainer to check the PTs cadence calculations and found it to be relatively accurate; within an RPM or two. it does flip out every once in a while and go completely inaccurate for a few seconds but it settles back down quickly.

mattm

I believe it's also only said to be accurate between ~40-130 rpm.. so when mine says ~200 when spinning down a hill, I doubt it's quite that high. But in the range they define it should be more or less accurate.

achoo

I just finished my first good ride with my new PowerTap, too. I went 75 km in 2:59:15, so a bit faster than the OP. And I'm about the same weight. And my peak wattage is extremely similar to the OPs.

Yet where the OP averages 245 watts, I got 156. And where the OP's normalized wattage is 316 watts, I got 205. Any ideas?

However, I'm using a Garmin 705 for a head unit.

I've had the Garmin for about a month, and just added the PowerTap. Interestingly, with the PT on I'm also seeing wonky cadence numbers every now and then, even though I have the Garmin cadence and speed sensor. Pre-PowerTap my cadence numbers never jumped all over.

Urthwhyte

The OP had a headwind, or you had a tailwind, or one of you did more or less climbing, etc...

heckler

nice always wondered what some of the bigger average strength guys like me would look like numbers wise.

achoo

Maybe so. I didn't have much wind, and I climbed about only about 600m over my ride, although some short sections (1 km or so) were maybe 10% or slightly higher grades.

Still, though, I don't think I should have been seeing "90 w" on my Garmin when it's set to show a 3 sec average power and I was going 35 kph while pedaling away at a steady 90 rpm. On a plot of my ride, I see a point where I accelerated from 25 kph to 38 kph over about 30 seconds on level ground, yet my average power over that entire time is 155 watts. I'm close to 100 kg - that seems like an awfully low wattage under those conditions.

I also keep track of what I eat, and the Garmin's calorie calculations have been a bit high but pretty consistent, and the Garmin says I burned 3524 cal on today's ride. That's probably more likely to be in the 2,800-3,000 cal range given how much I'll have to eat to not wake up ravenous at 2 AM tonight, but I'm seeing 1665 kJ from my power numbers, which off the top of my head tranlates to about 1,900 cal.

I originally had the Garmin set to show "Power" instead of the three-second average, and the raw power reading seemed to be dropping out pretty often, with lots of really low readings in the 10-20 watt range.

Add all that up, and I was a bit suspicious of my numbers. Then I looked here and saw the OP's post, where his ride is superficially really, really close to mine AND he weighs about the same, yet his power numbers are not just a bit higher, they're a LOT higher.

I'm wondering if my now jumpy cadence is to blame? Prior to putting the PowerTap on my bike, the cadence I'd get off the Garmin cadence reader would be really steady. Now, with the PowerTap, it jumps all over the place, moving up and down 10 or more RPM all the time. And more than occasionally being completely and obviously wrong. "238! - umm, I wish"

patentcad

I keep reading that kJ = calorie burn, but that seems awfully low given some of the readings I get for 50+ mile rides. Somehow I think that on a 55 mile ride, 3+ hours on the bike, I'm burning somewhat more than 1900 calories, or whatever the Ptap kJ reading is.

FlashBazbo

The OP is listed as a 215-pound rider, spinning an average of 63 rpm on a flat course, at a fairly low average speed! Impressive watts. Was the rear tire flat to produce that kind of wattage? Was the bike pulling a trailer?

Otherwise, on hills or sprints, I think we could see 5,000 or 6,000 watts!

Urthwhyte

wut

gregf83 

If you're suspicious about the accuracy of your numbers zoom in on the 1km hill at 10%. You should be able to check the reported average for that section vs an online calculator. Better yet google "Coggan stomp test" and check the calibration on you powermeter.

gregf83 

I didn't see any indication that the course was flat but with an average cadence of 63 my guess would be there was a fair amount of coasting and climbing going on which would explain the relatively high power numbers.

Urthwhyte

0's should be averaged in though, unless he's configured it funky

gregf83 

Correct, so when you average in the 0's while coasting your avg cadence goes down.

Urthwhyte

But so should your avg. power. Nearly 3.2 w/kg seems very high for only ~17mph

LorenzoNF

You can turn off the counting zeros for cadence and power separately. So it seems the OP had zeros counted for cadence but not for power.

petalpower

I'm waiting for my power meter ( Quarq ) and was wondering what all you guys are using for software to interpret the data?

I was leaning towards WKO+ - just unsure what the differences are between their packages.

tallmantim

LOL - yeah just noted that!

;-)

Isn't the garmin unit ANT+ that would get picked up by the head unit during configuration?

As someone else said - had cadence spike out to 200, which I was certainly not doing! LOL

FWIW, this was a climbing ride out to the Dandenongs locally - about 1100-1200 metres climbing plus I was pulling the group most of the way out there and back (although it was a lovely still winters day).

Cheers

BostonBullit

The Garmin is ANT+ but I hadn't configured the CycleOps cpu to use the garmin cadence sensor because I wanted to get an idea of how its cadence and distance readings where going to be. In the end it wasn't a very useful exercise because I decided to sell the 305, get a refurb 705, and upgrade the SL hub to ANT+.

mike868y

Can we please save this post for the next time some jackass tries to argue that average speed is a good determination of ride difficulty?

achoo

I still have something weird going on.

I loaded my ride into WKO+, and I see that I spent maybe 10-12% of my time with a cadence of zero - coasting. But the power profile graph shows 19% of my time I was putting out 0 watts. Also, the "power vs. time" graph that I'd think should drop smoothly from high power over short to lower power over longer times has a sudden drop in it where it falls from maybe 250 watts down to 200 or so watts in just a few seconds.

It looks like at lower power levels I'm getting some kind of dropout.

This is going to be FUN to track down. Not.

First thing I'll probably do is swap the cadence/speed sensors around since my PowerTap is almost certainly never going to find itself on my commuter bike. Or maybe try running without the Garmin cadence sensor.

grwoolf

I'm not sure this is the difference, but you can be turning the cranks and still have zero watts when soft pedaling. Also, I'm not sure about WKO, but some software does not factor in cadendence zeros, but does factor in power zeros (at least for average, may not apply here).