Powercranks - yes or no?

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CoachFergie
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by CoachFergie

Zoro wrote:
CoachFergie wrote:
Magellan3000 wrote:The PT was calibrated and zeroed for each ride.


You can calibrate Powertaps? When did this happen?

I thought it was a standard thing. It may be a Garmin thing, but there is an option for that that I use. I calibrate to 0 Watts with no load.


It was a rhetorical question, you can't calibrate Powertaps. The Garmin thing is just zeroing them.
Hamish Ferguson
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Zoro
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by Zoro

I can't calibrate my bathroom scale either, but I can zero it.

Why does anyone need to calibrate a power meter?

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CoachFergie
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by CoachFergie

Zoro wrote:I can't calibrate my bathroom scale either, but I can zero it.

Why does anyone need to calibrate a power meter?


Seriously?
Hamish Ferguson
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Zoro
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by Zoro

Well, yes. Why? Tell us.

If someone has a device, that gives a consistent number based on zero, why does it matter if it is nowhere close to any standard?

What matters is it is consistent / precise. I don't see the value in accuracy.
Last edited by Zoro on Thu Sep 04, 2014 6:35 am, edited 1 time in total.

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CoachFergie
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by CoachFergie

Zoro wrote:Well, yes. Why? Tell us.


Well seeing you spend $1000 to $5000 on a power meter one would assume you would like both valid and reliable data from it.

Personally it was doing my Masters thesis on cyclists racing and training with a power meter it was quite important to ensure the data came from a calibrated power meter. The NZ head Sport Scientist calibrates the High Performance squads SRM's before every session.

Even when you are not quite ready for marginal gains accurate power data gives you a better idea if you are making progress or just riding your bike with an expensive toy.
Hamish Ferguson
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Zoro
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by Zoro

Like my scale that says the same number all 5 times I step on it, that is all that is needed. Nobody wins anything on power readings. If it is consistent and precise, that is all that is needed. How did/does the unit matter in you NZ masters thesis?

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CoachFergie
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by CoachFergie

Zoro wrote:Like my scale that says the same number all 5 times I step on it, that is all that is needed. Nobody wins anything on power readings. If it is consistent and precise, that is all that is needed. How did/does the unit matter in you NZ masters thesis?


How do you know your scale is showing the right weight? Just because it is zeroed does not mean it is showing the correct weight.

Correct that power meters don't win bike races, but they do have a lot of other handy uses.

So you like precision, how do you know what you are seeing on the head unit reflects what is happening at the pedal?

Like any test of equipment used to test in an experiment one needs to calibrate it to ensure it is reading correctly.
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Calnago
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by Calnago

I think what Zoro is trying to say is that absolute accuracy in the power readings is not important in ones individual training. But consistency is. For example, if the meter is consistently measuring whatever force begin applied, and it shows a higher reading when more power is applied does it really matter what the absolute numbers are to an individual. As long as it can reliable measure an increase or decrease that is the important thing. Am I better than yesterday? Am I better than last week, etc. True, you may not necessarily be able to compare your exact power with someone else's exact power but in ones individual training program who really cares till race day.
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Dalai
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by Dalai

And what happens when you use a different scale or your old scale breaks so you need to buy a new scale? Can you rely on the previous weights noted and saved? Or what if you use multiple scales at the same time? Personally I would like to grab any set of scales I own and know the data is the same across scales...*

*I use 5 wired and wireless SRM's across my various bikes. I find great value in being able to calibrate each unit to confirm its accuracy so my data is consistent.

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CoachFergie
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by CoachFergie

Yes and no.

I have two sets of scales that use bioimpedence to give a body fat measurement. Both say zero when I jump on them but are 5kg apart when I jump on and the body fat measure vary hugely. Okay, for me this means just use one set of scales to see if numbers are tracking where I want them to.

Comparison of power is only relevant at the pointy end of the racing scene.

However any rider can use the power profile function in WKO+3.0 to see where they sit in relation to others even if it is just to track ones own progress. Or one can look at data from races to determine the demands of particular events to help with the preparation process.

Finally just because a power meter is zeroed before each ride does not mean it is giving reliable data from ride to ride. I have tested various power meters for NZ wholesalers and commonly find the zero offset drift quite a bit in a single ride.
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nathanong87
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by nathanong87

powercranks are kinda cool cuz u can do the kangaroo style

conversely you can't bunny hop with them though

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