Different riders at constant power

Actually, I don't think your experience has anything to do with VP pacing. Rather, it is consistent with one of my first observations after I got my PM -- it was difficult to hold power downhill and downwind and I always increased power when I started up a hill. Even today if I were to cover up the watts display I would inadvertently increase power going uphill. It does point out the difficulty of riding at a constant power without a PM (regardless of what people "feel" they are doing).

Hence one of the many great things about a meter, the efficiency of training increases!

Weight plays a factor, but I don't think you were doing as good a job at keeping power constant as you thought. When you get your power meter you'll see. I can feel like I'm busting my butt going down a hill, look down and see...... 175w. Later I may be trying to take it easy going up a hill, look down and see......285w.

Seeing the true power like that certainly shakes ones confidence in their ability to pace properly during a TT. (Cue RapDaddyo to start in about TT pacing in 3... 2... 😄 )

frenchyge said:

Seeing the true power like that certainly shakes ones confidence in their ability to pace properly during a TT. (Cue RapDaddyo to start in about TT pacing in 3... 2... 😄 )

Nah, I'm too busy trying to figure out how to actually ride a course at an optimal pace (whatever that is😕 ). But, when I figure it out you'll be the first to know.😄

frenchyge said:

Weight plays a factor, but I don't think you were doing as good a job at keeping power constant as you thought. When you get your power meter you'll see.

I'm sure that's some of it. I did have a HRM on though, and HRMs are pretty decent at gauging this sort of thing (approximately similar effort for many minutes), and my HR went DOWN on uphills, whereas if I wanted to ride alongside my friend on downhills, I would have my tongue out, eyes popping, HR getting into low zone 4, etc.

But that wasn't really the point I was trying to make. Just assume that for some reason we were both doing a perfect job of maintaining constant power, and that we were both going to end with the same average speed. It would still be likely for us to ride very different splits along the way. I guess I never really realized that before today. This always used to confuse me when watching the pros time-trial on TV; why do the splits seem to always be going back and forth? Don't these guys know all there is to know about pacing? They do, of course, but they have different weights.

kmavm said:

HRMs are pretty decent at gauging this sort of thing (approximately similar effort for many minutes)

After you get your PM, you might want to test this hypothesis.

kmavm said:

But that wasn't really the point I was trying to make. Just assume that for some reason we were both doing a perfect job of maintaining constant power, and that we were both going to end with the same average speed. It would still be likely for us to ride very different splits along the way. I guess I never really realized that before today. This always used to confuse me when watching the pros time-trial on TV; why do the splits seem to always be going back and forth? Don't these guys know all there is to know about pacing? They do, of course, but they have different weights.

I got that from your post, but like RDO I don't really think that's the cause of the effects you were seeing.

If 2 riders put out the same power over the same course, the lighter rider will win unless the course has a substantial net elevation drop. Their average speeds won't be the same, and that's why VP pacing works. (insert file-footage of RDO talking about VPP here since he's too busy to chime in.... :p )

frenchyge said:

If 2 riders put out the same power over the same course, the lighter rider will win unless the course has a substantial net elevation drop.

Actually, I should have specified that I was actually thinking of an up and down varying course like the one the OP mentioned.

If the course is slightly downward without any variation, then that favors the heavy rider. Weight is irrelevant on a perfectly flat course with no variation.

[quote="frenchyge If 2 riders put out the same power over the same course, the lighter rider will win unless the course has a substantial net elevation drop. [/QUOTE"]
That's not what I'm talking about. I wonder why I'm having so much trouble expressing this.

Imagine two different riders, both of whom are capable of averaging, let's say, 22mph over a given course. They do so at different powers, of course, because of differences in aerodynamics and weight. However, imagine that both of them have chosen a constant power output strategy, so they're each riding along, at their different, but constant for them, power outputs.

What I'm saying is, even though a time trial over this course for these two riders is a dead heat, the two riders' splits can be wildly different. E.g., it could appear to a spectator that a heavier. more powerful rider "dug in" during a flat part of the course, or that a lighter, less powerful rider really went all out on an uphill portion when both riders were just riding their maximal sustainable power from start to finish.

Am I wrong? If I'm not, I think that's slightly counter-intuitive. Maybe I'm just stupid, though 🙂.

Ok. Now I gotcha, and no you're not wrong as long as you're acknowledging that their power output will be different.

It's like in the TdF stages, where the big guys let a climber go off on an early climb, knowing that they'll be able to pull him back on the descent or flats. Different portions of the course are suited to one style or another, even if all riders can complete the entire course in about the same time.

kmavm said:

Imagine two different riders, both of whom are capable of averaging, let's say, 22mph over a given course. They do so at different powers, of course, because of differences in aerodynamics and weight. However, imagine that both of them have chosen a constant power output strategy, so they're each riding along, at their different, but constant for them, power outputs.

What I'm saying is, even though a time trial over this course for these two riders is a dead heat, the two riders' splits can be wildly different. E.g., it could appear to a spectator that a heavier. more powerful rider "dug in" during a flat part of the course, or that a lighter, less powerful rider really went all out on an uphill portion when both riders were just riding their maximal sustainable power from start to finish.

Am I wrong? If I'm not, I think that's slightly counter-intuitive. Maybe I'm just stupid, though 🙂.

I think you are correct. But, of course, both of these riders would lose to a clone of either one of them who rode the course at an equivalent power (NP) but with a VP pacing strategy.😄

FWIW, a number of times I have compared the power output profiles of experienced riders TTing the same hilly-to-rolling courses. What I've found is that, if you normalize the power to 100% of the individual's average (thus accounting for differences in absolute power output) and plot the data against distance instead of time (thus accounting for differences in absolute performance), the plots are usually nearly superimposable. IOW, experienced riders seem to pace themselves similarly when faced with the same problem of how to best distribute their effort to achieve maximum speed. That's not to say that mathematical modeling approaches to determine an optimal pacing strategy aren't useful, as they can be helpful in accelerating a less experienced rider's "learning curve", or for planning strategy when forced to compete on a course that the rider hasn't seen before. Still, I think what this does is illustrate is the power (pun intended) of self-optimization based on subjective perception/assessment of not only our effort, but also how fast we are covering distance.

both of these riders would lose to a clone of either one of them[/QUOTE]

Off-topic, but I've always thought it would be fun to rider with/against my younger self, if only for a day...I think it would be interesting to see/experience the age-related decline in my performance in such a direct fashion.

acoggan said:

FWIW, a number of times I have compared the power output profiles of experienced riders TTing the same hilly-to-rolling courses. What I've found is that, if you normalize the power to 100% of the individual's average (thus accounting for differences in absolute power output) and plot the data against distance instead of time (thus accounting for differences in absolute performance), the plots are usually nearly superimposable. IOW, experienced riders seem to pace themselves similarly when faced with the same problem of how to best distribute their effort to achieve maximum speed. That's not to say that mathematical modeling approaches to determine an optimal pacing strategy aren't useful, as they can be helpful in accelerating a less experienced rider's "learning curve", or for planning strategy when forced to compete on a course that the rider hasn't seen before. Still, I think what this does is illustrate is the power (pun intended) of self-optimization based on subjective perception/assessment of not only our effort, but also how fast we are covering distance.

Have you ever compared these performances against a mathematically derived optimal pacing strategy?

acoggan said:

Off-topic, but I've always thought it would be fun to rider with/against my younger self, if only for a day...I think it would be interesting to see/experience the age-related decline in my performance in such a direct fashion.

Interesting? Yes. Depressing? Also, yes. 🙁

Is there anyone who *wouldn't* want to see a 1999 Lance Armstrong race against a 2005 Lance Armstrong? That should be the next Discovery Channel special. They could even superimpose a virtual Mercx, Hinault, and Indurain in for comparison. Now THAT'D [censored] some people off! 😄

acoggan said:

IOW, experienced riders seem to pace themselves similarly when faced with the same problem of how to best distribute their effort to achieve maximum speed.

That's cool. I'm observing that the same effort distribution can still lead to wildly different splits, given riders of different weights. Am I on-track here?

kmavm said:

That's cool. I'm observing that the same effort distribution can still lead to wildly different splits, given riders of different weights. Am I on-track here?

Actually, I wouldn't anticipate "wildly" different splits. Assuming two riders of different weight (and power) are equally adept at deploying a variable power pacing strategy for fastest total time, they will be using more power in the same places (uphill, upwind) and less power in the same places (downhill, downwind) and in similar proportional amounts (e.g., 110%FT or 90%FT). So, while the actual speeds will be somewhat different as a result of the power/weight ratio (uphill) or power/frontal area ratio (flats, downhill), they won't be as different as they would be if the two cyclists were deploying completely different pacing strategies.

acoggan said:

Off-topic, but I've always thought it would be fun to rider with/against my younger self, if only for a day...I think it would be interesting to see/experience the age-related decline in my performance in such a direct fashion.

Heh, my old cycling club's records have my hill climb results from 1991. I constantly compare myself against those benchmarks 14 years later.

F1_Fan said:

Heh, my old cycling club's records have my hill climb results from 1991. I constantly compare myself against those benchmarks 14 years later.

Cool. So how are "you" doing then?