i don't know what this "one-sided" vs "two-sided" business is ... but i have vectors and am very happy with them. i switch them around quite a lot now, i broke one of the original pods but i am pretty sure it was cause i had the washer on the wrong side.

By far, the wired PT provides the most accurate and consistent data

There is a reason why strain gauges on the crank arms were not used for PMs until recently. There are inherently higher inaccuracies, even if you equip both arms. Maybe it's good enough for your purposes, but don't expect too much.

Of the new systems coming out, I think the Powertap crank spider one is the most promising for potential accuracy and price.

I've had stages for quite some time and I find it really consistent. Put a Powertap on my bike as well and the average was only 2 watts from each other.

I'd expect the Stages to be ~8W higher if they were both perfectly accurate.

Reminds me of the iBike data. You can always make the *average* come out the same as an SRM via calibration, but the interesting parts are where they differ greatly.

Everything is a use case, and everyone has different needs and constraints. There are differences in ease-of-use, cost, and data quality across different PMs. People make decisions based on cost and ease-of-use -- but many seem either to be unaware of differences in data quality or to think that those differences, should they exist, are unimportant. I've been pointing out that there are differences, but whether those differences are important I leave to the individual since they know their use case.

As it happens, I also have multiple bikes, of multiple types and components, in multiple locations, so I'm familiar with your conundrum.

What's important isn't how close they are on average. What's important is knowing when they're different, and by how much.

Agreed, it's the sole reason I went with a Vector rather than any other type.
I have two bikes with different crank lengths (shorter on the TT bike) and different chainring sizes, I ride both each week, and I have need (well... good use cases) for several different rear wheels.

It boiled down to the fact that the pedal type is the only thing that I keep constant every time I ride. I was using Shimano SPDs before, so the switch to KEO style was an easy one.

That's been my experience too.

This said, once PowerTap chainrings come out, and if the price stays as reported, I am buying me that.

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Next races on the schedule: none at the moment

I've now found that I'm too lazy to swap devices between bikes. I have my Stages on my Tri bike and it'll stay there. I'll buy either the Powertap Chain Ring system or a 4iii for my road bike this spring. That leave my commute bike and mountain bike without power. Seeing as I use both of those for commuting, at some time, I may do "something" about those.

So, for me, the argument about how easy these things are to swap is, at best, a moot point. I have power on the Computrainer and during the training season the Tri bike is on it so I can ride in aero on it. And, I have the Stages on it as well so I can compare the Stages power to the Computrainer power. Then, when I'm out on the road with the Tri bike I can see what power is happening. What I don't have at this point is power on any of my other bikes but I'm hoping that prices fall enough I can equip at least one of my bikes with it, just not sure which one for sure. And, being Canadian, the price of all that shit went up 25% over the past year due to the disparity between C$ and U$.

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BC Don
Pain is temporary, not giving it your all lasts all Winter.

I think that nicely links into my questions and concerns about the heated aspect of the 'which power meter' debate.

A. What is better.. A more accurate power meter or a power meter that is on only one of your bikes?
B. Why would I be bothered about a power meter that is 2% less accurate than another one when my gps computer is less accurate than both of them?
C. Is it better to train with a power meter that is a bit variable in its recordings than to train without one?


It seems like power meters are creating a sports team culture and people are more concerned about defending the reason they chose a specific device than they are about helping someone in their choices.

A.I would prefer a powermeter on the bike that I use the most and race on.
B.Umm, what the hell does GPS have to do with this? The reason to use a powermeter is because it is accurate and that accuracy is what is used for training, GPS is not accurate enough to give the sort of detailed information to get the same, so you would never use it for similar things.
C.It is better to train without one. Look, I spend a lot of time training. I want high confidence in the numbers to show if my training is working. If I had less confidence in my numbers, I may question the investment I made in the training. If my numbers do no improve over a block of training, is it because my powermeter is not accurate or is it because my training has not worked? Inaccurate data is worse than no data.

I don't necessarily agree.

If you're using the same powermeter on the same bike and it is accurate to itself it doesn't matter if it's not accurate against another powermeter as you're not using the other one.

I would just say that there is one caveat. It has to be accurate to itself, if not then yeah it's proved ly not worth the money.

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I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes

Well if it is accurate to itself, or it is precise, it should be able to be made accurate. Some like the power2max you will have issues with since it does not allow the user to change the slope, so that is an issue but will hopefully be addressed at some time.

The issue is that some powermeters on the market are not accurate to themselves.

What does "accurate to itself" mean?

Sorry.. should have explained more..
The GPS reference is in respect to run training. Many (myself included) use it to monitor our run trainiing to get detailled information from.

But.. I would probably guess safely that more people use GPS on a bike as their detailled training tool than people use powermeters purely because powermeters are a luxury item.
There are also people using their GPS bike computers more effectively and getting better performance improvements from, than others who are using their powermeters. I will put my hand up in shame as being one of those stupid powermeter owners! (I am re-entering the powermeter arena for the second time around now and am determined to actually use it much more effectively this time around)

So why would teams like Sky use the Stages PM? I'm assuming they want reliable data?

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Cervelo R3 and Cannondale Synapse, Argon18 Electron Track Bike

"built on a Look Keo platform"

What does this mean? Can I use it with my Shimano based cleats? Would I have to replace all my pedals?

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Cervelo R3 and Cannondale Synapse, Argon18 Electron Track Bike

They haven't won a Grand Tour since they switched to Stages. Just sayin'.

Consistent.

If that's what he meant, he could use a wristwatch. That's consistent. Speedometers and HRMs are also consistent.

Consistency is necessary but that may not be enough. If you're going to pay much (much) more for a power meter than you would for a wristwatch, a speedometer, or a HRM, you may want a bit more than consistency.

I see, but I would say that I would never use my gps pace from a run to the same level of precision as I would my powermeter data. If I went out and did a run and my average pace was 4 seconds per mile faster than a week before I would not necessarily think I was in better shape. It may have just been that I got luckier with stoplights. Instantaneous pace is even more of rough guide. My pace on a track I would treat much more like a powermeter though. But that is only part of it, because powermeters are going to help measure training load much better than a GPS computer.

Ok, so now we are getting somewhere though. I think you need to understand how to use a powermeter and what the data can show about your training. So when you had a powermeter, did you track your training stress balance? How did you measure your fitness? How did you set what your power goals for a certain workout were? I think you may have been using your powermeter similar to how you would use a GPS and that is why you may not be clear why the accuracy is important.