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· No Crybabies
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Discussion Starter · #1 ·
Did a 10 mile time trial last night. Purpose was to get good data for new coach I'm using. Almost flat, straight out and back. Full aero equipment. Very strong tail wind first half, head wind second half. Plan, this time, was to be very cautious with power on first half, keeping it around 270 watts and heart rate under threshold. Ended up averaging 30 mph on the out, and 20 mph on the return, for final average of 24 mph, 24:56 time. Found it useful to almost ignore speed, and just focus on power and heart rate. For what it's worth, this was the best time of about a dozen riders there last night, too.

Amazing how much different it was doing the pacing more correctly than I have apparently done in the past. The first half never felt strained (could have been the tail wind), and second half never seemed like a blowing up was in the works, but from 7 miles on it just seemed like a gradual building of stress. Never experienced the issue of power falling off while heart rate stays the same as I have recently.

Still finding it difficult to pace with the SRM, as there is no smoothing on the display (only on the computer afterwards). The power reading jumps all over the place, and you sort of have to do your own averaging on the fly. Maybe with much more experience you get a better feel for what a certain output feels like.

Looking for comments on pacing based upon the SRM info. Did I actually start out too easily? Thanks.
 

· leon2982
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Smoothing

I use a PT so the SRM might not work the same. On my PT I found changing sampling to every 10 seconds works a lot better than the factory setting. It's still not as smooth as I would like but it's managebable. Good work on you 10-miler. I do 3 intervals of 10K weekly with the goal of a gradual increase in power on each interval and each interval more than the previous. That last interval is really hard to maintain composure. This seems to help me train for how-to maintain near max effort in a manageable, under control manner; as much as possible anyway.
 

· No Crybabies
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Discussion Starter · #3 ·
Srm

leon2982 said:
I use a PT so the SRM might not work the same. On my PT I found changing sampling to every 10 seconds works a lot better than the factory setting. It's still not as smooth as I would like but it's managebable.
The way I understand the SRM works, you can vary the sampling interval. However, this is only for data recording purposes. For example, if you set it at 5 seconds, it will average, then record that data point, every 5 seconds. However, the display is completely independent of data recording. The display updates power every crank revolution, with no smoothing at all. Looking at the display, it's like this 263 - 271 - 258 - 277 - 290 - 255 ... and you sort of have to guess where you are. You can view the average display, but that's only the average since the start. You might be way off that at any given time.

They really should provide a smoothing feature in the display. Pacing was the primary reason I bought this thing.
 

· Squirrel Hunter
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Ask your coach!

Fixed said:
...Purpose was to get good data for new coach I'm using...

Looking for comments on pacing based upon the SRM info. Did I actually start out too easily? Thanks.
This is a question you ought to be asking your coach. In fact this is something you and your coach ought to have discussed in advance and worked out in training for this time trial. I assume that is the type of advice you are paying for. If you don't have confidence in your coach to either ask the question or take his advice then perhaps you ought to be looking for another coach.
 

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Discussion Starter · #6 ·
new

Keeping up with Junior said:
This is a question you ought to be asking your coach. In fact this is something you and your coach ought to have discussed in advance and worked out in training for this time trial. I assume that is the type of advice you are paying for. If you don't have confidence in your coach to either ask the question or take his advice then perhaps you ought to be looking for another coach.
Just started with him as of Sunday, so this was the baseline test for power/threshold.

Not that I don't trust him, but more heads the better.
 

· Cycling Coach
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Fixed said:
Looking for comments on pacing based upon the SRM info. Did I actually start out too easily? Thanks.
It's a little hard to tell on that horizontal stacked chart. A vertical view, perhaps with 30 second smoothing would better tell the story.

Part of the issue here is were you pacing for:

- maximal average power for the duration, or
- least time on course?

The two are not necessarily the same thing, and it depends somewhat on the nature of the course and conditions. Maximal average power is obtained by riding at an isopower. But that is not always optimal from a quickest time perspective.

As a coach, in performance testing I want to know what power a rider is capable of for a given duration/distance. However in preparing for a TT, then other considerations are factored into training, such as developing an optimal pacing strategy for the course and conditions, as well as managing the start pacing.

For interest, I have built a power pacing optimiser that will provide power pacing for each segment of a ride to minimise overall time (within the physiological contraints for the rider) and given the course profile and wind conditions. Here's a sample output:



Note how the rider can save 43 seconds in a 25-mile TT over an iso-power ride but average 5 watts less than their FTP (maximal average power for 1 hour).
 

· No Crybabies
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Discussion Starter · #8 ·
good thoughts

Interesting information. Doubt I'm quite up to that level of sophistication, but when I get a much better handle on what to expect, I think that will make sense.

Would your strategy apply to a completely flat course, or is it designed more around power climbing vs. descending and flats, etc?

With exception of start, turn around, and finish (last 1/4 mile?), my assumption was that on flat ground, highest average power would produce fastest time, so I was thinking the goals of determining average power and best time were close to the same. Not sure what I would do differently if I had either of the goals in mind.

One more question -- is that much variation in power normal, or would a more experienced time trialer be expected to maintain power more evenly and closer to average, if that were the goal?
 

· Registered
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sounds like the conditions (wind) make the data not very representative. 10 miles is also pretty short--why didn't you work harder earlier? I train/race with a power meter, but always keep in mind the advice Roy Knickman gave me a while ago (a pretty good source): in the end you've got to relate those numbers to perceived exertion. Time trialing is all about finding that spot right on the edge of perceived exertion-don't be a slave to the numbers alone.
 

· Cycling Coach
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Fixed said:
Interesting information. Doubt I'm quite up to that level of sophistication, but when I get a much better handle on what to expect, I think that will make sense.

Would your strategy apply to a completely flat course, or is it designed more around power climbing vs. descending and flats, etc?

With exception of start, turn around, and finish (last 1/4 mile?), my assumption was that on flat ground, highest average power would produce fastest time, so I was thinking the goals of determining average power and best time were close to the same. Not sure what I would do differently if I had either of the goals in mind.

One more question -- is that much variation in power normal, or would a more experienced time trialer be expected to maintain power more evenly and closer to average, if that were the goal?
The model is applicable on a flat course if you know what the head/tailwind conditions will be on each segment. Nevertheless, it is optimising power on variable gradients where the biggest time savings are made. If it's pancake flat and little wind, then the answer is easy - iso-power all the way, with perhaps a little easing up to that level in the first few minutes being sensible.

Iso-power is a very good place to start for fastest time but once there are significant chunks of the course with not insignificant gradients and different winds speed/directions, then iso-power is not the most optimal for fastest time.

The classic flat out and back with headwind/tailwind scenario for example is marginally optimised by slightly variable pacing (<10 seconds improvement over 40km). Slightly harder into the into the wind and slightly less with it. Wind is tricky though, as it typically gusts and so maintaining a smooth rhythm is difficult.


The variation in power recommended by the model is also determined by the individual physiological characteristics of the rider being modelled. These constraints are part of the model, so that, if for example, you could not sustain more than 110% of FTP for the 6 minutes required to get up a climb, then a segment would not make that pacing suggestion but instead limit power to no more than your physiological constraints.

At the least, FTP and MAP (Maximal Aerobic Power) are needed but if more data is available, then it can help.


Application in a TT by a rider "on the fly" means that modelling such a course needs to focus on large enough segments that matter.
 

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This sort of discussion, while interesting on an intellectual level, reminds me why I like cyclocross and mountain bike racing.

Although, heck, someone'll probably come out with a power-optimizing software for those, too.
 

· No Crybabies
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Discussion Starter · #13 ·
worse

threesportsinone said:
I really like all the data you find with your SRM, and thanks for sharing, as well.

However, just as an experiment, I think it would be interesting to see how your results differ without using the SRM, or just without being able to see the display.
I've done lots of time trials without a power meter or even HR. Typically, I go out too hard and blow about 2/3 of the way, resulting in slower over all speed. With the nasty headwind on the return on this one, it likely would have been worse.

It is amazing how good 320 watts can feel at the beginning of a 10 mile time trial, even assuming threshold is somewhere around 270. Takes a good minute or two for heart rate to catch up.

A few years ago, I was doing frequent tests on a Computrainer. After zeroing in on average power, I found that staying as close to average power as possible seemed to result in the best times. Also, it is much easier to maintain steady power on the CT compared to on the road, as conditions are more controlled, and maybe because there is some inherent smoothing that the SRM does not have.
 
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