Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon rogermbyrne am Mo 19. Mai 2014, 21:13

So I went against all of my previous comments and bought the Stages power meter ;) should be here end of May :fingers crossed:
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon Erdnah am Mo 19. Mai 2014, 21:27

Congrats!
Please share your impressions once you collected some experience using it.
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon mi67 am Mo 19. Mai 2014, 22:37

Erdnah hat geschrieben:P2M as well as Stages only calculate left right power!

P2M (like SRM or Quarq) measures both sides, because torque from both sides is delivered via the P2M spider to the chain. The only additional requirement is to recognize which stroke comes from the left and which one from the right leg. To do so, P2M has a position sensor, which also serves as the cadence sensor, and of course to calculate the power by multiplying torque and angular velocity.

Rotor needs two sensor devices because Rotor doesn´t measure in the spider, but with strain gauges in the crank arms. Stages measures one only the left side.
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon vantage84 am Di 20. Mai 2014, 07:25

rogermbyrne hat geschrieben:So I went against all of my previous comments and bought the Stages power meter ;) should be here end of May :fingers crossed:


I'm excited about your impressions! I think the concept is as good as P2M or SRM and it's not so susceptible to crashes like a pedal power meter. :daumen:
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon Erdnah am Di 20. Mai 2014, 20:31

mi67 hat geschrieben:
Erdnah hat geschrieben:P2M as well as Stages only calculate left right power!

P2M (like SRM or Quarq) measures both sides, because torque from both sides is delivered via the P2M spider to the chain. The only additional requirement is to recognize which stroke comes from the left and which one from the right leg. To do so, P2M has a position sensor, which also serves as the cadence sensor, and of course to calculate the power by multiplying torque and angular velocity.

Rotor needs two sensor devices because Rotor doesn´t measure in the spider, but with strain gauges in the crank arms. Stages measures one only the left side.


Let us agree on: P2M (any powermeter measuring torque in the spider) always measures a cumulated value of both sides.
They cannot discriminate between the two cranks/legs, ie pedaling with only one leg will lead to a calculated value for left right due to the position sensor. In other words: a heavy upward pull of the left leg will lead to a (calculated) higher right leg power.

I can see drifts of left right power distributions according to different efforts/conditions and degree of fatigue.
Low power flat terrain spinning: more "left" power. Heavy grinding uphill and/or fatigue: more "right" power.
I cannot say whether this is due to actual changes of left right leg power output or plus/minus mobilization of the opposite leg by upward pulling.
I do not trust the absolute numbers and oftenly actaully mistrust them. I guess unless you constantly see differences of >10% any value is "okay" and will depend on whatever. If you always read 60%-40% (or even bigger differences) power distribution, you might concentrate on your pedaling and try to find out the reason. Yoou will find relevant tests on DC Rainmaker´s hp.

I am pretty sure I lately saw a pro using a Spider based powermeter (SRM?) plus a left Rotor crank (presumably in order to get the "real" left leg power output).

vantage84 hat geschrieben:
rogermbyrne hat geschrieben:So I went against all of my previous comments and bought the Stages power meter ;) should be here end of May :fingers crossed:


I'm excited about your impressions! I think the concept is as good as P2M or SRM and it's not so susceptible to crashes like a pedal power meter. :daumen:


NEARLY as good as a Spider based powermeter, ie astonishingly good result according to DC Rainmaker. Spider based measurements are still "the Gold Standard" compared to crank and/or pedal based powermeters. Prices definitely are good arguments for eg Stages. I am also looking forward to the testing by rogermbyrne!

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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon mi67 am Mi 21. Mai 2014, 00:15

Erdnah hat geschrieben:Let us agree on: ...cumulated value of both sides. ...

Agreed upon this and all following thoughts.
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon rogermbyrne am Fr 30. Mai 2014, 12:47

It has arrived..... Stages promised delivery on the 29th which of course was a bank holiday so no problem.

Still fresh in the box, now a quick install and use it, then find out I don't have any Power ;)

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I assume Power data will now be uploaded to Strava after each ride so I guess we'll see how it's working, don't have another so can't compare it.

Anything you'd like to see tested that I could test or just get on and use it? ;)
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Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon cl am Fr 30. Mai 2014, 14:15

Coggan has some test rides in "the book". I gave my book to some one else for reading, so I can't tell you how to ride these specific tests. But you can ride Coggan's short FTP-Test:

kurtkinetic hat geschrieben:Figure out your Functional Threshold Power. Be sure your body is rested, this is like a short race effort. Allen and Coggan's protocol is as follows:

20 minutes easy warm up
3 x 1-minute wind ups with a minute rest between (100 RPM pedal cadence)
5 minutes easy
5 minutes all out (hard at first, but not so hard that you can't complete the effort)
10 minutes easy
20-minute time trial effort (like the previous 5-minute all out effort, keep in control, hard but steady, you don't want to over cook it and die at the end)
10 to 15 minute cool down


& something to read:
http://www.flammerouge.je/factsheets/functhresh.htm
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon cl am Fr 30. Mai 2014, 14:29

... and the best way is to ride & ride & ride with the PM AND to analyse & understand your PM-data (GoldenCheetah is a great program and it is for free). If you do so you will get a feeling for your powerdata and your FTP (the most important value for the training zones)
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Re: Leistungsmesser - wie zum besten Kosten/Nutzen Faktor?

Beitragvon rogermbyrne am Fr 30. Mai 2014, 14:47

Thanks for the links will read up!

Yeah I think I'll go out tonight and do a couple of times 20 min Teststrecke and just see how the data comes out.
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