Which makes the accomplishments of a mini-imp like Emma Pooley really stand out as superb.

Hugh

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Genetics load the gun, lifestyle pulls the trigger.

Sami typically doesn't include zeros in his numbers. Strava has his ride as 267 AP/274 NP for 4:33, which seems pretty reasonable.

I have tested 2 different powertaps vs 2 different cranks (SRM, QUARQ), on the road @ ~250 watts (all properly calibrated and zeroed).
In both cases, the crank-based watts were 2-3 watts higher.

Not sure what you mean by "calibrated" but you are talking about a 1% drivetrain loss, and I've not seen it nearly that low when accurately measured.

The HPVA site has a couple of lab tests... one by Spicer, and the other by someone famous from back in the day... can't remember his name. Of you could look at the Friction Facts lube test... and add in the pulley losses.

If zero wattages make your VI look higher, and you are absolutely flying along when you are at zero wattage, then my guess is that I'd rely less on VI in that situtation. Or said another way, when you do put out power make sure you are getting an advantage from it, especially the higer powers. Really cool to see you put out the same wattage over years but manipulated your coasting time. This premise may get lost among those that just gloss over your post, but there is absolute gold in the concept in there if you apply that knowledge to all IM bike rides.
FWIW, my VI was 1.07. I'd normally consider that unacceptably high if it was a long training ride. We were lucky that the Kona course and conditions that day left us many opportunities to save energy while still flying! I mentioned before that I was coasting by guys that were pedalling. Even if they were softer pedalling, there were missing opportunites to save energy, cool down and lower HR.

Cranks were calibrated with a known set of weights in order to recalculate the slope.
The details of this have been discussed on this forum.

You are right, the total drivetrain losses should be higher.
According to friction facts, total losses on a clean Dura Ace setup @ 250W should be around 6W total, so my finding of 2-3W is within the measurement error.

The point is the difference between PT vs SRM/Quarq is MUCH less than the 5-10% often quoted on this forum.
It should actually be closer to 2%.

I don't know what people usually state, but I figure 8W drivetrain loss. Which is 4% at 200W and 2% at 400W.

Friction Facts didn't have a derailleur attached, and so had no pulley losses. In their lube test the chain loss ranged from 5-8 W for a pristine system.

They did in fact do a separate pulley test, which for DuraAce measured at 0.15W (for the set).
Results of the different pulleys varied from 0.06-1.3W.

[/quote] Yes and no. I'm thinking about it for next year. At the same time, there were plenty of other indicators. It's another data point. For whatever that is and isn't worth.[/quote]

Rappstar,

Which would be your main indicators/data points besides HR regarding the state of your body (clumsy phrase, I know, but I can't think of a better one) at any given moment during a race?

Also, if you think that the state of your body at any moment during the race is important for overall performance, and if you think that monitoring that state in real time if critical for the same reason, which indicators/data points would be superior to HR?

And which indicators/data points would be most useful in comparing their real-time feedback with other indicators/data points?

For example, on the bike, which ones would be more useful than HR in comparing their feedback with power?

From your posts I get the feeling that you are an analytical mind who likes to work with factual, objective information, so I'm curious to know which ones of those main indicators/data points meet those criteria.

Thanks very much for your feedback and thanks for sharing your knowledge and experience in here and with such detail.

Nuno

Agreed. My post-race analysis of my file has made me much more comfortable with the high VI on the course on that day. I'm naturally a very low VI guy so I was a bit disconcerted during the race but I'll definitely use the knowledge I've gained to adjust my strategy in response to the course and conditions in my future races, and specifically at Kona if I do the race again. My impression from looking carefully at a few different power files from Kona this year and mine over the past few years is that the unique conditions of that course really provide some significant opportunities to impact your time by making more significant adjustments to where you output your power than in a typical IM course or training ride.

Definitely agree...VI is directionally helpful in a lot of cases, but in terms of understanding "the bad kind" vs. "the good kind" of variability, especially in a long race, it's worthless and misleading. I've written about this on another thread, but because of how Normalized Power works mathematically, its delta relative to the average is heavily influenced by zeroes, which are often good, more so than big surges, which are very often bad. Fun w/ numbers using my file to demonstrate...VI was 1.03 (236/229) with about 4 min 40 sec <20W. Back solving a bit, if I didn't coast at all, and instead during all those <20W times I surged, my VI would be the same only with 520 watt surges. VI would have been 1.03 (244/237W), and probably I would have not been all that much faster in terms of time since wind resistance at 30 mph is stout, and with all the variability coming from the wrong end of the bell curve (sum of 4 min 40 seconds at 520W). Better metrics needed for sure...

Dr. Skiba has probably something better with xPower, but all I've been able to really tease out is that xPower is lower and different and not necessarily better. The only difference is that he uses a 25 second exponentially weighted moving average rather than a 30 second moving average, and other than saying "the body does things exponentially", even Skiba does not say it's demonstrable better than Normalized Power. He just says it could be, might be, or thinks it might eventually be

http://www.physfarm.com/bikescore.pdf

Yes and no. I'm thinking about it for next year. At the same time, there were plenty of other indicators. It's another data point. For whatever that is and isn't worth.[/quote]

Rappstar,

Which would be your main indicators/data points besides HR regarding the state of your body (clumsy phrase, I know, but I can't think of a better one) at any given moment during a race?

Also, if you think that the state of your body at any moment during the race is important for overall performance, and if you think that monitoring that state in real time if critical for the same reason, which indicators/data points would be superior to HR?

And which indicators/data points would be most useful in comparing their real-time feedback with other indicators/data points?

For example, on the bike, which ones would be more useful than HR in comparing their feedback with power?

From your posts I get the feeling that you are an analytical mind who likes to work with factual, objective information, so I'm curious to know which ones of those main indicators/data points meet those criteria.

Thanks very much for your feedback and thanks for sharing your knowledge and experience in here and with such detail.

Nuno[/quote]
Ideal world? You'd have a ANT+ core temp pill that showed temp. There are some skin temp gauges, and having one of those built into an ANT+ HR strap would be nice as well.

It's definitely only a matter of time before we see both of these in BTLE versions, because they are so valuable for firefighters and military.

There are also HR straps that measure respiration rate (strain gauges in the strap); I don't know how valuable this would be, but if you were wearing a HR strap anyway...

But I think if you could get core temp during the race, that'd be one thing I think would be pretty neat. Because when it's been done, you can see some pretty dramatic implications.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Rappstar,

Appreciate your reply.

So, for now, no indicator for the main metric - core temp.

Still wondering if HR is of any use on race day (I have power too).

No use at all - none as an indirect measure of core temp for example?

I'm not a very experienced athlete. I've done a few MTB stage races, and I'm just starting with Ironman (I've only done two).

So very much on a learning curve, and eager to continue, and my question comes from that.

I still tend to go mostly by feel - ie, by my evaluations of RPE. But I want to know for what exactly might the other indicators be most useful.

Power I think I have a good idea now. Power and RPE I'm starting to understand and trust.

But HR, not so much. I have been surprised a few times on race day when I check it.

Which always makes me suspect that that indicator is trying to tell me something and I'm not listening/using it.

Thanks again for your feedback and insights.

Nuno

I've never worn a HRM for an Ironman. I'm thinking I might try one for IMAZ. Just to see if there's anything I might get out of it.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Thank you once more for the reply.

I'll be looking forward (again) to read you about IMAZ.

I always find what I would call your self-forensics - and the general forensics of the day too - extremely interesting and useful.

Nuno

Additional thoughts after yesterday's 4:02? I don't disagree with your skepticism, but still feels like 350W or so might be reasonable for that kind of speed...

If other files from Florida are available it might help

No new thoughts, unless he's a freaking brick.

ETA: Though I don't know what the wind was like yesterday, but looking at some of the times for riders I do know (in terms of power output), it was probably relatively calm/normal. But I'm open to being corrected.

I wish there were a quantitative analogue to power for the run as well. Here is Josh pushing Donna Mummert, former Kona and RAAM finisher and current ALS sufferer, in a wheelchair to a 2:59 at the hilly Harrisburg Marathon. While Josh is a veritable beast on the bike as his Lake Placid and Kona times and power numbers attest, I still believe his 1:18:29 run course record at SavageMan, a full 5 minutes faster than anyone else has ever gone there, is the finest achievement ever at SavageMan, the site of some pretty amazing swims, bikes, and runs over the years.

Video, may require you to like Appalachian Running Company to view: https://www.facebook.com/...hp?v=672481119438319

Had this thread saved from 2013! Be cool to see how 'twitchers faired on Saturday...