Oh yeah, I realize that a lot of people don't want to share their power data on a forum so please feel free to e-mail me at: chris at chriswhyte dot net.

Thanks, Chris

Probably because the goal of a race is to go as fast as you can, and that is not necessarily equivalent to having your AP close to your NP.

Paulo, I would actually disagree with that statement. I think the goal of a race is to go as fast as you can on the least amount of power. The point is that there's a balance. I believe that your AP is reflective of your bike split time and NP is reflective of the true physiological cost of that ride. So, high AP with low NP is one approach to achieving that goal. It's also reflective of a well-balanced ride, imho.

Your comment implies that if my NP was 195 watts, for example, I would have gone much faster. If so then I don't necessarily agree. Keep in mind, I'm not just trying to ride fast, I'm trying to perform the bike and run as fast as possible.

Thanks, Chris

No offense, but you're too much of a numbers geek and I'm not enough, although I like to think I'm just enough of a numbers geek.

What I said still stands as my opinion, having your NP close to your AP is not the best racing strategy for any kind of course. Also "burning matches" might prevent you from winning a bike race, but I'm not convinced it will affect your running performance.

Oh, let me clarify one thing... When you've ridden with a PM as much as I have then get pretty in tune with your power, bike split time in different conditions. I'm interested in seeing other people's power data between the two years since things aren't quite adding up in my mind. If you have some explanations as to why then I'm all ears...

Thanks, Chris

I apologize for giving you an explanation that you can't fit into your somewhat distorted way of seeing racing. Racing is, and always will be, about going faster.

I know that you spend a ton of time tracking this sort of stuff and have looked at a bunch of data so you are in a much better position then me to give an accurate answer. I wonder though if you pedalled(worked) too much coming down from Hawi which obviously gave you a higher average power for that stretch which then would have given you a tighter VI. Was the incremental speed that you gained there worth it in terms of total time. If you coast more there and "save" those watts would you have been better served to have a higher VI and pushed more watts where it would given you more bang for the buck?

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http://bigisland-will.blogspot.com/

Thanks for the post. I also usually bike around 5 1/2 hours. I haven't done an IM since I bought my Ergomo this summer so I'm interested in your numbers. It's funny, 185 watts doesn't sound like a lot, but after a few hours, 185 gets tough.

Anyway, I can't find info on the VI data you refer to. I see it on my summary data in my software and I figure it must indicate the variability of your power. Is this correct?

Geoff from INdy

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Geoff from Indy
http://www.tlcendurance.com

Geoff

VI is from cyclingpeaks and it is the Variability Index. VI = norm power/average power. You might want to check out http://www.cyclingpeakssoftware.com/power411/defined.asp for details as to how norm power is calculated.

As you can see with the exchange between Paulo and Chris, there is debate about the extent that VI matters, particularly with regards to pacing an Ironman. What you'll see if you take a look at power files from IM rides is that a VI much higher than 1.1 will not be followed by a good run.

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Jason
Dig It Triathlon and Multisport
http://www.digittri.com

Coasting would raise VI?

I think sometimes with a powermeter sometimes people must be tempted to conclude they need to ride with nearly even effort but here's why I think that is flawed to some extent. When you ride uphill at a slow pace, wind resistance is greatly reduced, so there is a bigger payoff for increased effort. When going downhill, because wind resistance is exponential, it would seem wasteful to use a lot of watts.

But what you are saying, it is easier on your body to go at a nearly even power all day, especially since you still have a marathon to run.

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Geoff from Indy
http://www.tlcendurance.com

Paulo, it seems to me that people who result to insulting others during a response have simply unconsciously conceeded that they have nothing constructive to offer in their defense -- usually because they're wrong or don't understand. So that's the best you can do?? Wow, I'm thoroughly disappointed...

Ok. I'll bite (as unconstuctive as this might be)... I could have done that bike averaging close to 200 watts -- I have no doubt. Producing that kind of power would have produced a very fast IM bike split (for me). Unfortunately walking the IM run isn't my goal. Care to elaborate?

Btw, you have agreed wholeheartedly with Rick Ashburn's specific comments on racing with power in a few threads I've read on this forum yet, somehow, my approach (which very closely reflects his approach) is "distorted." Interesting...

Thanks, Chris

What is interesting is that you feel insulted by what I am saying.

I am done with this subject and wish you the best of luck in your quest. Thank you for your posts.

[reply]....

But what you are saying, it is easier on your body to go at a nearly even power all day, especially since you still have a marathon to run.[/reply]

That would depend on how you train. I personally cannot accelerate and decelerate a lot without zapping most of my power (hence being one of the crappiests road racers around)

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Reverend Dr. Jay
Lake of the Pines Triathlon fastest bike course record holder - Golden State Super Sprint fastest tri course record holder - Wildflower Long Course slowest run course record holder (4:46:32)

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"If you have a body, you are an athlete." -Bill Bowerman

Hence, one reason for the experiment... :-) I can tell you that my AP at IMC last year was 181 watts and my NP was 200. I did not run well at all (3:52). My bike and run fitness as compared to IMH '06 were very close to the same, imho.

I think a look at some power data of other athlete's who did IMH this year and last year would help a lot. Conditions on Saturday were definitely trickier than last year and, as we all know, conditions are a large part of the puzzle.

Thanks, Chris

However, if you climb that roller at well above FT there's a good chance the physiological cost was much greater over that period of the same distance (which included uphill and downhill) and yet you gained zero time. Prime example was all of those people who passed me working very hard going up the rollers and then I blew by them on the downhills. I'm not working hard on the downhills because they're coasting and recovering. Do this repeated times over a period of 5hrs and you end up with a higher physiogoical cost with little debate.

So, this is not directed at your comment specifically, for someone to make a blanket statement that "burning matches" won't impact the run is rediculous in mind. If that was the case then we should all be doing the IM bike at an IF of something well above .85. If you burn enough matches at some point then the physiological cost of doing so will not only impact your run, it will impact the remainder of your ride. The challenge and, therefore, the question is: Where's the balance?? I'm simply doing a little experimenting in attempt to share my experience and data with others. That's all...

Thanks, Chris

Depends on what you mean by, "best racing strategy." If you mean fastest time for a given amount of effort -- then we have to wonder how we go about measuring the effort of a long, variable bike ride. Is the total effort the average power, or the normalized power? Or is it something else that doesn't lend itself to such measurements?

Any thoughts?

Yes. Some people love their powermeters way too much.

The best racing strategy must be that which leads to the fastest time, and placing relative to your peers. The optimal AP vs NP depends on the course - the best strategy will depend on hills, flats, and wind, and for those racing in the front like pros in hawaii - tactics.

Many athletes with power meters are now over thinking the bike - similar to when heart rate monitors became popular.

Joel

Some observations to throw out...

Keep in mind that Chris' AP is what is tied to his bike split. NP is a "physiological cost" estimator. It's interesting that Chris had a higher AP this year, but a slower time. The only reasonable explanation is that his aerodynamics were different -- and that includes course conditions. What appear to be "similar" conditions are rarely so. Little changes add up. Bike, helmet, how many people are around you, etc. Something to keep in mind.

Here's the notion behind comparing NP and AP: AP determines your bike split (as long as you're not too variable in your riding). AP is the actual total work divided by the actual total time. It's the "real, actual" average power.

NP is, instead, an adjustment of the power file that, in essence, "punishes" a rider for parts of the ride that are harder than others. Harder efforts (in 30 sec chunks) are exponentially more costly than easier ones. NP is not a "real" power number, but is a way of converting the actual AP effort into something that more closely reflects what the rider actually did.

As NP becomes greater than AP, we see something interesting. If equally fit twin riders A and B both had an AP of 180 watts, their bike splits will be very nearly identical. If, however, rider A had an NP of 185 and rider B had an NP of 200, then we would conclude that rider B is going to be more tired getting off the bike. Rider B rode significant parts of the course at a very high effort, and coasted on other parts. Same bike split -- different "tiredness." Who's going to run better?

This is not to say that a perfectly even effort is best. It's not -- variable courses require variable efforts for the fastest time. The question is "how variable?" Lots of IM rides are in the VI = 1.08-1.10 range, among both elites and AG'rs. What Chris (and I) is (are) trying to figure out is whether a VI in the 1.03-1.04 range is better. On the one hand, I can think of lots of reasons why it is. On the other hand...ultra-distance fatigue is a funny and mysterious thing. Maybe we are best off going steady; maybe we need rest periods (coasting & soft-pedaling), even though they might not appear optimal under the NP calculation. Maybe different people need different things.

Chris ran well, but he always does. So, that's no help. ;-)

Have any other powermeter users compared their AP and NP at different races and found any patterns in how they feel getting off the bike? I've had good success keeping VI in the 1.03 to 1.05 range, and not so good success (running) when it creeps up into 1.08-1.10.

"If equally fit twin riders A and B both had an AP of 180 watts, their bike splits will be very nearly identical."

There are instances where two identical riders with the same AP would have two different splits. What if rider A rode the same watts for the entire race at 180w. AP = 180, NP=180. Rider B pushed the hills harder (less wind drag) eased up on the downhills (more wind drag) and ended up with AP of 180, but NP of 190. Which rider was faster? Of course rider B would be more 'spent', but they both produced the same amount of kj.

Can't tell for sure -- it's one of those things where you'd have to actually run the numbers. In variable conditions, a VI > 1.0 is almost certainly faster, but only up to a point. There is an optimal VI and going farther above it is slower. I settled on the 1.03-1.04 range because that's what works out to be fastest on real-life rolling, breezy courses, assuming each athlete has a maximum NP they can muster for the course (by choice, in the case of triathlon).

Still -- if their APs were the same, and their VI's were in the 1.0 to 1.10 range, the bike split will be very close. But their fatigue level might be very different. Hence, our quest to better understand pacing choices. Various pacing strategies (within reason) can all produce IM splits within minutes of each other. But, the resulting fatigue cost can move disproportionately among the group of riders.

Interesting point that just occurred to me: Powermeter users know that riding in a group paceline produces a far more variable power profile than riding alone. Imagine you settled into a group (legal, of course) in an IM, riding at your target average power. I would suggest that you can still blow up because your VI is so high. A paceline is far from steady. Coasting, surging, coasting, surging...we see plenty of paceline-sitters still blow up on the run.

pretty simple to do on analytic cycling. Going to bed now, maybe I'll run a model tomorrow to see how much time we are talking about. I will make the comparison between VIs of 1.00 and 1.08.

Here's a concept that might just blow your mind. What if the fact that they blew up was related to their running training and ability? ;-)

Rick,

Nicely put. Thanks for taking the time for doing something that I probably should have done earlier in the thread. Although, you explain it much better than I do.

Like I said earlier, I haven't always run well (IMC '05) but maybe why I usually do is because I ride pretty conservatively and well balanced. At IMC '05 I rode with an IF of .78 and a VI of 1.1 (my highest ever). So that's a little bit of help...

Thanks, Chris