Measured using a powertap g3, Turbo and trainer road, im 3.4w/kg. A lot of people tell me it must be measuring low, as to race and place where I do they’d estimate about 4w/kg – im not technically blessed to make up a shortfall.

TT’d with a powerpod today and its recorded 10m at 4.4w/kg for 23:40 at 40.5kmph average.

I suspect my real w/kg is somewhere in the middle although that ^^ might indicate a 3.8-4w/kg ftp is achievable, but i just find the inconsistency annoying, id have been quite slow if id relied on Trainerroad suggested threshhold indicated via the pod – henced i used RPE.

My much more aero club collegue (bmc time machine plus all the gear and more experience) rode 22:38 at 211w from Stages -2.2kmph faster than me yet 100w less.

Kinda thinking aloud really….

Maybe you’re not trying hard enough when doing TR FTP tests?

Hmmm. That’s making a lot of assumptions. It’s easier to assume neither his nor yours are correct, but they’re correct within their own right.
Use yours as an indication purely based upon your other tests, so if you know your Max is 4.3 then ride according to that, whether it’s actually 4.3 doesn’t matter, it’s only for you on your bike.

IMO an aero position better than yours ain’t making 100w difference over a course.

Ive always thought his ftp was low – a reported 230w for someone knocking out 10m in 22:38.

Anyhow im more worried about my two and what my w/kg actually is!!

Congratulations, your ride on 6/05/17 recorded an improved threshold power value! Your new power threshold is 304 watts. Would you like to set this as your threshold power for all future workouts

From Todays Plan (Torq). No way im putting that into Trainerroad, id die a horrible death!

My much more aero club collegue (bmc time machine plus all the gear and more experience) rode 22:38 at 211w from Stages

Maybe if he weighs 30kg and has the frontal area of a postage stamp!

My much more aero club collegue (bmc time machine plus all the gear and more experience) rode 22:38 at 211w from Stages -2.2kmph faster than me yet 100w less.

comparing other peoples power data is useless
and

id believe the power tap over the power pod

1. I’m very dubious of the basis of power pod numbers.

2. Loads of people’s FTP values appear to be fantasy. Don’t pay any attention to them.

3. It’s very annoying when you start to doubt your power meter. I’ve run my just serviced power tap and left leg Pioneer together and found a 7% discrepancy. I just choose to believe the biggest number

Theres quite a few tests whih show good numbers from powerpod, including the DC Rainmaker comparisons with other PMs.

I do wonder. My trainerroad power went down this year but my results and sustainable power had visibily increased. Perhaps my powertap has gone wrong or something in Trainer road has altered becuase my setup is the same.

Perhaps i should use the powertap wheel on my next TT and see what happens.

At least by doing this TT ive now got a power pod base measurement for threshhold with it.

Edit: oh wait hold on, I’ve just looked back at some of my data from Hillingdon TT’s which has coasting and a short downhill curve which I don’t pedal. Last year using an info crank I averaged 254w on my PB, last week 266w, and today on a dual carriage way with 100% continuous peddling a no coasting whatsoever 322w – and I’ve seen the last six weeks doing 2 x 20’s. And we all know that indoor power is “less”.

Could be more real than I think!

A) indoor ftp is probably bollocks, there’s nothing to distract you from the pain, so unless you are super strong mentally you don’t get everything out.
B) not sure about what if anything you can derive regarding ftp from a 23min race effort.
C) it doesn’t actually matter what your ftp is, or if its different with different equipment, just so long as its repeatable.

I personally stick with my same Stages across all my bikes and indoor and outdoor riding.

I can get very very close to outdoor figures indoors.

I want to like the Powerpod- that DCR article is such a good advert but quite frankly, it seems useless for actually telling you what output your body is producing. I think it’s forte would be CDA stuff alongside another PM- for everything else it just seems ridiculously fickle and unreliable.

FTP as a raw number for bragging rights is irrelevant outside of Zwift race Categories.
FTP for actually understanding your Lactate Threshold for pacing is crucial and the key metric in pretty much all Cycling!!

Just my 2p.

Don’t know your numbers, but assuming you did 310w at 4.4 puts you around 70Kg…or 240w at 3.4 on the trainer?

I’m consistently 10% down on the trainer so sssuming your the same then 265w…and 5% off your 20 minute TT effort is 295w.

I’d probably set it around 280w and see how it goes, but turn the intensity down to 90% when using TrainerRoad

I ignore indoor power and only believe field testing, after all where are you racing? Look on bikecalculator.com for ood ballpark figures for speed for power, and hence time for distance. The ios app has extra refinements for crr and aero efficiency – think skinsuit and shoe covers instead of jersey and shorts.

I find this provides a pretty good calibration. I suspect you PP is reading a little high, and mine is now a little low after adjusting for position and a disc, but within device consistency is really all that matters.

Powercal has always provided consistent results, that’s why I like it 😉

EDIT. Bikecalculator puts 40.5 kph at 260 watts. That’s what you did, or thereabouts. It won’t be over 300, I’d suspect accuracy of better that 3%.

Stages numbers always seem low to me. But as long as it’s consistent it doesnt really matter, unless it makes you think you are more aero than other people when you just have a low reading PM. If this means you dont spend time on aerodynamics when you should be, that’s a problem.

I dont know anyone I consider serious who’s using a Power Pod (just saying) but as long as it’s consistent, it doesnt really matter. Except if it misleads you about aerodynamics as above. Personally, I can’t see how it will work when you are using tribars, and DC rainmakers test was on road bike – he couldnt get a decent riding on his tt bike.

DC’s readings were low due to vibrations on the original set up. There is a much better mount now for TT bars. I find my TT readings are within 1% of bikecalculator values, and I validate bikecalculator predictions against other riders with DFPM’s. Hillingdon, being a short non-flat, closed loop is perfect for this I also use much longer loops up to 100 km.

Once correctly calibrated, I’ve found mine to be accurate and reproducible, and I use it racing. Off to do some testing later today on mine.

Cyclingtips did a podcast recently about power meter accuracy that was quite interesting. The message I took from it is that most power meters have to make some kind of estimation to give you your power and there are lots of factors that can affect how ‘true’ that number is.

As such, comparing power data between different riders, devices etc is of limited value. As long as you follow the manufacturers calibration/maintenance advice you should have a consistent number that is useful to you.

Oh and comparing indoor/outdoor power isn’t that useful either, even with the same device

I see no reason to ignore power indoors? Ultimately, Cycling is just turning a crank with your foot.

The power meters job is to report an objective measure of that input. Everything else being discussed is superfluous. Your body doesn’t know you are cycling or that you are on your TT bike or that you are indoors (obviously your mind does but that’s not the same as indoor power being obsolete 😉 )

The closer to your cleat you can record this input and the less assumptions and calculations that have to be made to produce the figure- the better surely?

We’re measuring power to quantify how much work we are achieving REGARDLESS of external influences.

That Powerpod and Cycling calculator can get close to each other merely shows they both use a comparable algorithm- albeit a very sophisticated one. But actually, anything that’s not measuring torque is hugely subjective.

Of course, for comparing efforts on one machine in one position, those guesstimates are accurate enough to provide a useful pacing tool.
But using the exact same strain gauge based meter, calibrated regularly for temperature, across all your bikes is the only reliable way to consistently measure your workload.

So I just completed a 150k road ride with the powerpod. It got more an more accurate, even showing 0 on coasting now. I’ve had my best club ride for ages, pulling strong turns, competing climbs and winning sprints. I watched current power and the reactions were fast and consistent in line with RPE.

Knowing previous results on the same ride I’d predicted a 225w average. I got home to find it showing 230w.

“Accurate to within 1 club run” quite an accolade 😆

Sorry it’s hot and it sounded funny in my head 🙂

Did you get rid of an info
crank for a PowerPod? Seems like a backward step

Not if your swapping between bikes on a weekly basis.

Crosshair, my point was I’ve done this ride many times with my info cranks, and although there are variable I’ve average 200-230 watts. For the PP to show 230W, and to acurately display coasting & sprinting within seconds on my head unit tells a story about its accuracy IMO.

Kryton that’s brill! As I say, I love the concept of the Powerpod but the more I read about it’s use in practice, the more apparent limitations seem to rear their head.

If you can get to a place where you are happy with the data then it’s serving it’s purpose 🙂

Not wanting to brag but i complained earlier in the thread i thought the numbers were high.

Well, doing my turns today its been commented about how strong im riding – on climbs too – and even asked to reign it in a bit after splitting the group, dropping riders. And these are decent riders too.

Perhaps im not doing myself or the PP enough justice!

It got more an more accurate, even showing 0 on coasting now.

No wonder your early numbers were out, when you’re initially setting a Powerpod up anything other than 0 when coasting means you’re doing something wrong.

When is set up properly not only does it show 0 when coasting but can also tell if you’re braking in a descent or suddenly get in a draft and display exactly when and where this happened using the GE plug-in for the Isaac software.

Well, doing my turns today its been commented about how strong im riding – on climbs too – and even asked to reign it in a bit after splitting the group, dropping riders. And these are decent riders too

Yeah, I bet they all sat there thinking how amazing you are, smashing it up on a club run…

You’re more than welcome to join ours and test your mettle flange, it wasnt easy.

This turnaround needs some Strava-nalysis I reckon

The only fit and forget, never have to worry, power meter I’ve used is the Powercal. For 30 second averages it provides fine summary data. For anything more detailed, it doesn’t.

The beauty of the powerpod algorithm is that it measures wind speed to calculate all opposing forces. As opposed to deflection in a Wheatstone bridge resistance circuit. CH, you should look at how bikecalculator predicts your circular rides, you learn a lot about relative position, for example.

The fact that instantaneous measurements, summed over a ride, coupled with wind and drafting, provides some nice info after a ride/race. The coolest thing is when it records zero watts on my fixed wheel when I’m not applying force. I can’t swap to put the Stages on that bike. But then cadence is power anyway 😉

But it’s not fit and forget is it.
If you hit a pothole, you have to check its level again.
If you adjust your set up so the wind deflects in a different way or in anyway blocks it, you have to recalibrate or move it.
If you put it on a different bike you have to recalibrate completely.
I appreciate the Powerpod calculates in an incredibly advanced way but it’s still calculating rather than measuring what is coming out of the balls of your feet- which is ultimate the purpose of a power measuring device.
The bike aerodynamics, your position, your clothing, draft, headwinds, rolling resistance, weight and gradient are all constantly and infinitely variable during a ride.
Accounting for all that to make a best-guess stab at something that can actually be measured directly seems woefully inefficient!

I don’t think a single sided Stages is perfect either mind you…..

But it’s not fit and forget is it.
If you hit a pothole, you have to check its level again.

He said the Powercal (which uses HR as a proxy for power) is fit and forget, not the Powerpod.

Nothing single sided is perfect, it’s a massively compromised solution. They can work well for a lot of people, but anything which only measures half of what you do and assumes the other half is identical is never going to be faultless. Stages is probably the worst of the lot with their shambolic reliability.

The bike aerodynamics, your position, your clothing, draft, headwinds, rolling resistance, weight and gradient are all constantly and infinitely variable during a ride

You might think so, but tests have shown that we are all creatures of habit when it comes to position. I ride on the drops a LOT. The gradient is measured extremely accurately. But adding a skinsuit and pointy helmet will change things – hence I went out fully aero’d this afternoon to try and not scare children!

Kryton, I’ve now calibrated my PP based on the 100 km ride this afternoon, and it reads exactly as it should based on prediction. To do this requires careful analysis of Wind Scaling and Aero parameters – basically these are mount-specific.

You need to open up a nice circular ride that has NO drafting in Isaac, the longer the better. Then go to Analyse/Check Calibration. this will provide an estimate of the goodness of fit for a closed ride and make suggestions on rescaling the wind and aero. For some reason, mine was set for drops not TT this afternoon. look at the new change in watts (mine changed from Avg 247 to 196) and “Accept” this change.

Isaac will then extract a new profile that you can upload to the meter. Future readings will benefit from this increase in accuracy immensely.

I’ll be riding a 10 on Thursday and will check the predictions again then.

As I say- I see how for a fixed position ride it has meaning but for multi-discipline or indeed any kind of dynamic riding, it’s putting a wet finger to the wind.

Practical example from today. Absolute toast 25miles into the group ride. Long climb. Off the back. Not wanting to get left behind but similarly, wanting enough in reserve to complete the remaining duration.
Sometimes on the drops in the wind, some out of the saddle, some on the tops for maximum lung capacity but one important metric required- to stay beneath Lactate Threshold! So I look at my power and target 300w regardless. The same 300w measured indoors, outdoors, on four different bikes and in every different position and corresponding to my current FTP.

50mph descent down the other side and bingo- get back on. (Ok so they had to wait at the junction 10 seconds 😀 )

But the important thing was no matter how I threw myself around on the bike- I had objective context to my output.

I don’t see how an algorithm based device can get close enough in anything approaching this kind of example.

Since most of that power is “gravity watts”, you’ll find that your position for CdA estimation will not change the power appreciably. The algorithm estimates power to overcome air resistance, friction and gravity. The proportions of these change with terrain. If I climb at an indicated 330 Watts most of that power is rate of increase of potential energy (although friction increases too with incline). I did just this last night up Hedsor hill.

I cross check long circular rides with bikecalculator, because this negates wind and terrain completely and provides a good estimate of summary output. In fact, I’d believe this over and above my Stages (broke two in wet and cold rides).

I love Physics, in case you hadn’t guessed 😉

Ok appreciate the point about gravity smoothing out the guesswork by weighting the sums in that instance but it was just an example to illustrate that not all rides are mono-positional.

It doesn’t change the underlying problem either- it’s calculating what you probably have done rather than measuring what you are doing. And instead of relying on one sensor- it’s cross referencing 5? (wind speed, incline, temperature, altitude and wheel speed?) so way more scope for inaccuracies.

As I say, I’m not anti PP- I find it fascinating. But for the average user, it’s unduly fickle.

When Kryton mentioned that perhaps his PP was right after all earlier, my thoughts were “if only he had had some kind of device to measure his power- then we’d know for sure!” Like, well, a Power Meter 😆

Well the future for every Tester is to couple a powerpod and a DFPM, and give real time CdA readouts. At the moment this can only be done post ride, but that is a Garmin problem, not a Powerpod one.

It’s basically a pitot tube, accelerometer and inclinometer. It takes speed from a speed sensor to give Power = Force x Speed. DFPMs do something similar, in that they all have an accelerometer to measure cadence to give speed of crank, and do the same sum – hence you get cadence from a Stages. Powertaps, measure hub speed.

When set up correctly, like most things, it’s very good, reproducible and accurate. It just takes a little care to do so properly.

all I need to do is lose 30kg and I can turn pro