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Rick Murphy's Normanalized Power Thread
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TOPIC: Rick Murphy's Normanalized Power Thread

Re: Rick Murphy's Normanalized Power Thread 7 years, 3 months ago #26338

  • Ron Ruff
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Another interesting data point for me today. There is an awesome 6.25 mile about 6 miles from the house, and I've raced up it on many occasions. Today I thought it would be fun to do unstructured intervals on it. I haven't done intervals since last summer... none, zero. Last Sat I raced up it for the first time this year and averaged 268W, compared to my best ever of 276W.

The intervals were ~45 sec at ~400W with recovery periods of ~85 sec at ~175W on average. 21 intervals all together. That's just what I felt like doing I guess. About 2/3 of the way up I remembered that my iBike has a GP readout, so I switched to that screen, and was encouraged by a reading of 294W. That's a lot more than I should have been able to do. And I kept that pace going to the end... even increasing it a bit to 298W. AP was 256W. I expect I'll be able to raise both these numbers quite a bit with more practice.

In case you are wondering if the iBike was responsible for this anomaly, I did all the "on" portions seated, and I always tweak the results slightly after the fact based on a constant elevation gain... I figure the actual altitude of the mountain doesn't vary even though the altimeter does. Also, the period it uses for adjusting the tilt is 5 min, which is a lot more than the interval duration. So it couldn't have been over-predicting the "on" power by a significant amount.

I've had similar results to this when doing short intervals on a trainer... the AP is a lot closer to what I could have done with a constant effort than the GP. At least for me, the GP doesn't seem to work as well as AP for determining what I can do in this kind of variable effort.

Re: Rick Murphy's Normanalized Power Thread 7 years, 3 months ago #26353

  • kraig
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Ron Ruff wrote:
Another interesting data point for me today.

<snip>

The intervals were ~45 sec at ~400W with recovery periods of ~85 sec at ~175W on average. 21 intervals all together. That's just what I felt like doing I guess. About 2/3 of the way up I remembered that my iBike has a GP readout, so I switched to that screen, and was encouraged by a reading of 294W. That's a lot more than I should have been able to do. And I kept that pace going to the end... even increasing it a bit to 298W. AP was 256W. I expect I'll be able to raise both these numbers quite a bit with more practice.

In case you are wondering if the iBike was responsible for this anomaly,

<snip>



sounds like a fairly good "scatter the plot" type of ride.

the opinion I'm evolving to after using the ibike for a couple months in conjunction with my SRM Pro, is that the ibike generated #'s are conceptually very similar to the calculated GIZMO POWER generated #'s using my SRM/PT...y'know, in that the ibike #'s should be used for entertainment only (just like the inferred GIZMO POWER #'s), so to speak, for durations less than around an hour.

Over longer durations than that, though, I think the ibike provides far more actionable information than GIZMO POWER could ever hope to provide.
-kraig

Re:Rick Murphy's Normanalized Power Thread 7 years ago #26434

  • Kirk
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So, it's been a long while, but in the interest of applying evidence-based stuff to the world of exercise training...

I was wondering if anyone out there on the interwebs in the interim has discussed or noted the reasoning regarding why one would suggest that using a x^4th weighting on GP is valid when the data presented to support this weighting fits a linear function equally well? Especially when noting that basal metabolic rate is essentially 20-40 watts to start with and that lactate can exceed 1.0 at this level of exertion. I just thought I'd check back to see if anything has changed.

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26531

  • kraig
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I can easily do this workout:



but some folks don't think it's possible given my 55-ish MP of 270W at the time...hell, come to think of it, I don't even think you can do this ride.

Prove me wrong! ; - )
-kraig

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26532

  • SteveI
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kraig wrote:
hell, come to think of it, I don't even think you can do this ride.

Prove me wrong! ; - )

Is that intended as a challenge to all readers?

What exactly do we have to do to be deemed to have "done" the ride? 30 secs at 600W every 5 mins, with approx 120W in between each 30 sec effort? Looks like you put in an extra 30 secs effort between the first two but apart from that it was every 5 minutes? What was your 55 minute NP?

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26533

  • kraig
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SteveI wrote:
kraig wrote:
hell, come to think of it, I don't even think you can do this ride.

Prove me wrong! ; - )

Is that intended as a challenge to all readers?


I guess so.


What exactly do we have to do to be deemed to have "done" the ride? 30 secs at 600W every 5 mins, with approx 120W in between each 30 sec effort?


Oh, I don't know - if I was prescribing this, I guess I'd say something like ramp into a 30 second effort such that you wind up doing/averaging 85-90% of your 30 second max (for a 30 sec duration) and then soft pedal for 4:00-ish give or take...do as many as you can or stop when you get bored. Adjust as necessary next time.

What was your 55 minute NP?


GP seemed out of line with the supercomputer. Give the ride a shot.
-kraig

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26534

  • kraig
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Kirk wrote:

I was wondering if anyone out there on the interwebs in the interim has discussed or noted the reasoning regarding why one would suggest that using a x^4th weighting on GP is valid when the data presented to support this weighting fits a linear function equally well? Especially when noting that basal metabolic rate is essentially 20-40 watts to start with and that lactate can exceed 1.0 at this level of exertion. I just thought I'd check back to see if anything has changed.


IOW, x^4 when at rest (i.e x=0) is not zero?
-kraig

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26535

  • SteveI
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kraig wrote:
Oh, I don't know - if I was prescribing this, I guess I'd say something like ramp into a 30 second effort such that you wind up doing/averaging 85-90% of your 30 second max (for a 30 sec duration) and then soft pedal for 4:00-ish give or take...do as many as you can or stop when you get bored. Adjust as necessary next time.

GP seemed out of line with the supercomputer. Give the ride a shot.

Okay, gave this a go today, it wasn't a GP buster for me. My best ever 30 sec power is 745W, but that was out of the saddle up a hill, so can't really compare with a seated effort on a turbo. Only had time for 5 reps, but did the 30 secs at an average of 617W. Did 4 mins moderate in between each one at an average of 179W. Only gave me a GP of 330W for 19:40 vs my best 20 minute power on the turbo of 335W.

Having said that, I did a 277 TSS ride yesterday, and certainly couldn't have managed 335W for 20 mins today. I only did the 5 reps because I bailed out of my planned session of 2 x 20 at 303W after 10 mins because I couldn't take the pain in my legs any more. I'd say the 20 mins of 30 secs / 4 mins was less painful, overall, than the 10 mins at a steady 303W, despite the 10% higher GP.

Re:Rick Murphy's Normanalized Power Thread 6 years, 8 months ago #26536

  • kraig
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SteveI wrote:
I only did the 5 reps because I bailed out of my planned session of 2 x 20 at 303W after 10 mins because I couldn't take the pain in my legs any more. I'd say the 20 mins of 30 secs / 4 mins was less painful, overall, than the 10 mins at a steady 303W, despite the 10% higher GP.


Sounds busted to me...You did a maximal 10 minutes and then followed that up with a non-maximal 20 minutes at +10% - that's a lot of error...

Regardless, you have proved me right thus far...I mean, I told you that you couldn't do that ride. ; - )

When you have more time you should give it a go again...and, to be fair, you can stand for the first 6 pedal strokes of each of the "on" bits.
-kraig

Re:Rick Murphy's Normanalized Power Thread 6 years, 1 month ago #26769

  • Kirk
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kraig wrote:
Kirk wrote:

I was wondering if anyone out there on the interwebs in the interim has discussed or noted the reasoning regarding why one would suggest that using a x^4th weighting on GP is valid when the data presented to support this weighting fits a linear function equally well? Especially when noting that basal metabolic rate is essentially 20-40 watts to start with and that lactate can exceed 1.0 at this level of exertion. I just thought I'd check back to see if anything has changed.


IOW, x^4 when at rest (i.e x=0) is not zero?


Nope. Resting lactate can exceed 2. X^4 is not generalizable.

Re:Rick Murphy's Normanalized Power Thread 5 years, 6 months ago #26924

  • kraig
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Kirk wrote:
So, it's been a long while, but in the interest of applying evidence-based stuff to the world of exercise training...

I was wondering if anyone out there on the interwebs in the interim has discussed or noted the reasoning regarding why one would suggest that using a x^4th weighting on GP is valid when the data presented to support this weighting fits a linear function equally well? Especially when noting that basal metabolic rate is essentially 20-40 watts to start with and that lactate can exceed 1.0 at this level of exertion. I just thought I'd check back to see if anything has changed.


...it's been awhile, but, it seems that there are still some critical thinkers out there (thanks for the heads up from my GP sources!):

www.cyclingforums.com/t/488594/sequencin...ity/180#post_4029191

...that thread is full of some good entertainment...though, skimming the portions of the thread I was linked to, makes me feel like I man, that's totally 5 minutes of my life I'm not going to get back! LOL! Perhaps "Dancing with the Stars" would have provided more entertainment? But alas, if it wasn't enough entertainment for me, it's probably simply due to the fact that my "Functional Entertainment Threshold" was set too low? How might I test that hypothesis?

While I'm on this thread... it seems that Dr. Gizmo and his acolytes haven't seen the SRM screen-grab in this thread that shows that things in gizmo power land are beyond the realm of possibility for this guy...imagine how all those long course triathlete guys have been mislead by all of their soft pedaling moments...

Did I also read in that thread I just linked to that Dr. Gizmo has finally admitted that his "pinning a single number on the whole deal" based power meter work is not science, but, rather, something else?
-kraig

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