BigPoser

So someone in my club mentioned Power Pod to me the other day and after looking them up a bit today, it really doesn't look too bad. At least DC Rainmaker seems to like it.

PowerPod In-Depth Review | DC Rainmaker

Anyone have any experience with it? Used their products? Thoughts?

Thanks in advance.

Brandon

PepeM

I used to have a Newton, which was the previous version of the PowerPod. Unfortunately I never compared the numbers with my 'real' power meter, but it seemed to work reasonably well. I think that as long as you understand all of the caveats of the way it measures power, it can be a useful tool. Funnily, I think that its biggest issue is that most will always be wondering just how reliable the numbers they're reading are. Another thing work considering is that if you do a lot of indoors training it won't be very useful in those instances.

dr_lha

Biggest issue with it is that for not much more you can get an actual strain gauge based power meter. For only $60 you can get a 105 crank arm version of the 4iii Precision Power Meter (with DCR Clever Training discount) for example. If it was $50 or $100 cheaper I think it'd be a killer product.

Otherwise, worrying about accuracy of power meters is only something to do if you have 5 of them on your bike like DCR does. If you only have 1, why worry?

RPK79

I've thought about this product. Still on the fence.

BigPoser

That does sound good in theory, but since I have Campy my options are certainly limited. 4iii doesn't even make a Campy compatible version and I won't get a new crank just to accommodate a power meter.

Others I've looked at are Brim Brothers and Power 2 Max (still $1290 though).

dr_lha

Fair enough. Stages make Campy compatible ones I believe, but they don't have them on their online shop, so no idea how much they cost.

With a Campy drivetrain, Powerpod is clearly the cheapest way to get power for you. Well there's PowerCal as well I suppose.

Cychologist

I have been riding with the Power Pod most of the season. Seems to work pretty well. (Actually it measures my power about 200 watts less then I'm sure I am putting out. ;-) )

I haven't used any other power meter to compare it to, and just picked this up to be able to converse with my son who is a serious duathlete. He said there are so many variables that you can't really compare one person's power with another, thank goodness. But the Power Pod does give meaningful readings for me to compare efforts on my rides.

For the price and with Rainmaker's review, I went for it and am pleased I did.

PepeM

As far as I know the Brim Brothers thing has yet to be shipped anywhere, so I wouldn't bother with it, especially since you can get a proper power meter for the price that one is supposed to cost.

BigPoser

That is too bad. They have a great set up. I really like the idea of switching bikes, not moving any gear, and still having a power meter. Oh well.

The Power Pod is looking pretty good.

PepeM

Yes, I agree. All power meters seem to come with a compromise hardware-wise (pedals being the most versatile.) Just checked the Brim Brothers facebook page and they claim their first units have finished production, but who knows when they'll ship, plus they'll probably go to early backers first. Then there is the question of whether it actually works... Fwiw Luck recently announced power meter soles for their shoes at Eurobike, which is another interesting approach but again, until I see them actually being sold I wouldn't hold my breath.

K.Katso

A friend of mine has one. It was a ***** for him to calibrate and he's still not sure it is completely right. He says it really wasn't worth the trouble and wishes he had bought a Stages instead.

Redbullet

The system might have strong limitations, such as:

- Riding on the hoods vs. on the drops might require some 5-10% bigger power for the same speed and the same road, but I doubt the system can identify the difference.
- Lateral wind might require important increase in power for the same speed and the same road, which might not be measured by the device (it looks that the device is influenced by the front wind only).

Overall, the inconsistency of the measurement in various conditions might be somewhere around 10-20% (or maybe more). Not so appealing...

As a benchmark: it took me 4-5 months of hard training to increase my power with 10% on an indoor trainer. If the inconsistency of the device would be 10-20%, then... it is only a toy.

RNAV

Ha! You're funny. Have you even read DC Rainmaker's review?

chaadster

The calibration ride has to be done how often? Is it before every ride, just the first ride, or some periodic interval? I presume you'd recalibrate if you made any significant equipment, position, or clothing changes (e.g. between summer and winter kits).

BigPoser

I think you're right. The CEO of the company replied to a quite a few of the questions asked in the DC review and mentioned that the calibration is only done on the very first ride.

Cychologist

It recalibrates on the fly. So after the initial calibration, just ride.

Redbullet

DC Rainmaker does not say that the device compensates for changes in position (on the hoods / on the drops), nor for lateral wind; only those together might create inconsistencies of 10-20 % or more in measurements. He only makes some indirect suggestions, to make the reader to self convince that everything is accurate. Subtle (but well known) marketing technique. Furthermore, he says something about some "miraculous" auto healing, suggesting that no matter what, the system will finally be accurate.

I am way above 6 years old, I can't believe in miracles, thus, I don't "buy" it.
But, whether you "buy" those or not, I will not say you are funny. Ha!

RNAV

Actually, DC Rainmaker says this:
In other words, the unit was accurate, regardless of the position he was in.

So, I couldn't find that statement anywhere in his in-depth review. Would you be willing to cite, specifically, where DC Rainmaker made that statement?

Actually, he provides a plethora of data in which he simultaneously compared the Power Pod against up to three other well-established power meters, and the result was that the Power Pod largely mirrored the results of the other meters. So what, exactly, are you considering "indirect suggestions . . . that [it] is accurate"?

Here's what he actually says:
I think what he did was provide a data point. Nowhere could I find the word "miraculous," nor could I find any suggestion that "no matter what, the system will finally be accurate." Could you help me find where he said that?

Bottom line, your opinions are predicated with a whole lot of "might"s, and not a lot of facts. You're welcome to pull things out of thin air if you like, but I consider it disingenuous to just make stuff up and pass it off as fact. In other words, you might be full of bs, and significantly lacking in facts and data.

Redbullet

Hey, hold your horses, there's too much passion ...

There is no problem if somebody is confident that a hole directed forward can measure the impact of lateral wind and that the same hole can identify the differences in power spent between "on the hoods" and "on the drops", or between various levels of resistamce of the roads, or the influence of tire quality, tire pressure, etc. Or if somebody believe that systems misteriously "heal" themselves.

There is no problem if some people do not believe those because there are no technical grounds to support such assumptions.

I don't use a power meter - because it's too expensive yet, nor a power pod - because I don't trust it. Also, I don't think DC Rainmaker can overrule physics.
But if others believe that, in fact, DC Rainmaker makes the rules, be sure that's not a problem for me.

Cheers!

RNAV

Excellent disarming, btw

Here's the big picture: you're claiming this thing is a toy, because physics says a forward facing hole can't account for crosswinds or changes in position (and other things), right? Or am I mistaken?

Being that I'm an aviator, I am intimately familiar with the fact that nearly all aircraft operate with only a forward-facing "wind meter" a.k.a. static line port -- no other direct measuring device for crosswinds or tailwinds. Yet, using only a forward-facing static line port, aircraft are able to account for crosswinds and tailwinds.

So you claim a forward facing wind port can't account for anything other than a headwind, which contradicts my knowledge and experience. I ask you to provide some kind of proof or data that supports your claim. Then you put your hands up in the air and say "Hey, if you want to believe that malarky, I'm not stopping you."

How this power meter works makes sense to me. You say it can't be accurate, and cite physics as the reason why. Can you please explain your position further so that I can understand why you feel the way you do?

And as you explain yourself, please understand that thousands of aircraft flying around the world are quite literally doing exactly what you're saying can't be done. So make the explanation a good one.

Redbullet

Ok, see a huge post below. But anything more would be wasting time. I don't want to convince anybody to buy or not to buy the device.

1. A number of factors influence the power that is generated whilst pedaling: The front component of air resistance / friction, the lateral component of the same, the aero characteristics of the system (e.g. on the drops, on the hoods, clothes characteristics, etc), the road type (surface characteristics), tires pressure, tires quality, others. All of them change from one ride to another and most of them change during the same ride.
Power Pod only measures the first component of the above and tries to aproximate the power used to overcome it. But the rest of components that are not measured have a large influence (e.g.: change in aero position easily account for 5-10%.). I think that failing to measure and include those parameters in a complex algorithm is a strong limitation that prevents obtaining consistent results.
The traditional power meter ignore all those individual parameters and directly try to measure the forces used to overcome all the factors together (measurement force / power at pedal, crank, chain ring or wheel level). They are not prone to missing measurement of many complex individual factors, because they simply measure the aggregate result of all together.

2. In practice, the difference between “on the drop” and “On the hoods” is around 1.5-3 km/h – another 5-10% change in air speed without modifying power. I doubt that the front hole of powerpod can identify your position and keep the power reading constant, as long as it perceives change in air speed.

3. When weather prognosis shows lateral wind around 15 km/h (50% of my speed) on my favorite road, that usually slows me down with 2-3 km/h, which means 6-10% of my average speed in calm conditions. I only guess that a plane flying with 500-900 km/h does not encounter lateral wind of 50% of its speed, thus, the influence of lateral wind versus its forward speed (or versus frontal air speed) might be much, much lower than in our case. And in lateral wind, the planes rotate their position and have some kind of “plan parallel” movement; that angle and other parameters might be used to calculate the lateral component of the wind – I guess. But there is no such rotation and plan parallel movement of the bike.
Besides, I guess that airplanes do not use the measured air speed to calculate the power that is generated by their engines - do they? (although airplanes are free from road rolling resistance, tires quality and pressure, passengers’ clothes and their unexpected changes in aero position, etc…).

chaadster

I'm not a pilot, aeronautical engineer, physicist, or in any way qualified to assess the validity of the science underpinning the Power Pod, so I won't enter that fray, but I will say that, even back through the iBike Newton, that everything I have seen regarding this type of indirect force measurement has validated its accuracy as a power meter. Are there caveats? Yes, sure. Is it inferior to direct force measurement? Yes, sure, in an absolute sense. Is it inappropriately or ineffective as a training tool? Absolutely not. For most types of general riding and training regimens, it is both accurate and consistent, providing good foundational data.

For cyclists trained enough that drilling down into 10sec data blocks is revealing and instructive, then PowerPod is not the tool for you. But for riders doing 2 minute intervals and 10min blocks at Tempo type training, I have not seen anything to call into question PowerPods utility for such use.

RNAV

Ok, thanks. I don't want to waste time either, or convince (or not convince) someone to buy the darn thing. So I'll just say my piece and we can call it good.

This device measures power by doing math. 1 W = 1 ((kg * m2)/s3). In other words, how heavy you and your bike are, how far you go, and how quickly you do it. That info is easy: you tell the system how much you and your bike weigh, and it reads your speed from your speed sensor and distance from your cycling computer. Do the math, and you've power. Now, what about wind?

If there is zero wind, then the velocity of the air entering the wind port is equal to your speed. Headwind? The velocity of the air entering the wind port is greater than your speed. Tailwind? The velocity of the wind entering the wind port is less than your speed. Crosswind? If it is a truly perfect crosswind, then the device reads the same as if there were no wind, because in effect there is no actual headwind or tailwind component. But that pretty much never happens, so any crosswind would be registered by its corresponding headwind or tailwind component.

Thus, on a perfectly flat road, maintaining a constant 15 mph, it requires more power if you have a headwind; less power if you have a tailwind.

If you keep the power constant (200W), then you go faster with a tailwind; slower with a headwind. Hence, your position is irrelevant to measured power output. If you keep the power constant 200W and the wind constant (5mph headwind), but make yourself more aerodynamic (in the drops), then you go faster. If you make yourself less aerodynamic (on the hoods), you go slower.

The device also has an accelerometer, to measure rate of acceleration, and inclinometer (to detect grade), and a barometer (to detect changes in pressure, and hence, elevation). In other words, it's got all the necessary data inputs to do the math to determine your power output.

And this is demonstrated by the data provided by DC Rainmaker. If there might be inaccuracies and errors, as you assert, then why does the Power Pod's numbers so closely match the other 4 strain-gauge based power meters that were also on the bike? Shouldn't there be huge discrepancy? Interestingly, strain-gauge power meters don't directly detect power either; they detect gauge factor and then do math to convert that info into power. Anyways, the fact remains that, based on the actual data DC Rainmaker provided, the Power Pod is just as accurate as any other major player on the power meter market.

My understanding is that is not how things work. Your power is your power, period: 1 W = 1 ((kg * m2)/s3). No where in that equation is air resistance, bike position, tire pressure, etc. All of those things impact how fast you go for a given power output, but they have zero influence on what power you actually put out.

Again, not really. None of those things have anything to do with power. They do, however, affect speed for a given power output. The device simply does math to determine power.

You just proved my point. If you keep the power the same, but improve aerodynamic efficiency, you will go faster. And the Power Pod will detect that the bike speed and the air velocity increase at an identical rate and an identical amount, thereby recognizing the improving aerodynamics and will display the same power.

Depending on the aircraft, it is entirely possible to experience a crosswind that is 50% of forward velocity, especially in the takeoff/landing phases of flight. Specifically in the landing phase, it is necessary to align the longitudinal plane of the aircraft with the landing runway, so as to not land angled. Otherwise in flight, yes, planes do "crab" into the wind to fly drift-corrected. I don't personally know of a plane that determines engine power output via airspeed computations, but I digress.

Anyways, thanks for keeping a cool head and settling me down in a mature fashion. Kudos to you!

PepeM

Your description of how it works is not quite accurate. This device does use things such as an estimated drag coefficient and rolling resistance (both of which it gets from the calibration ride) to do its calculations. So changes in position and/or equipment do affect the accuracy of the measurement. The conditions will have to be somewhat extreme for the error to be 10-20% though, especially if you look at longer time intervals. During instantaneous measurements it could be off by such amounts, but the same occurs within different 'real' power meters.

One neat side effect of the above is that if you have both a 'real' power meter and a power pod, you can do aero experiments on the fly to determine how many watts changing position saves you or what difference those $2k wheels really made.

PepeM

Good description here*:

*As you probably noticed, that is from the Newton, not from the Power Pod. As far as I know the principles used in the Power Pod are the exact same, but I could be wrong about that.