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-   -   Just started training with Power? Post your questions/comments here! (http://www.bikeforums.net/33-road-bike-racing/488667-just-started-training-power-post-your-questions-comments-here.html)

tanhalt 12-03-08 11:44 AM

Quote:

Originally Posted by umd (Post 7956377)
4 power meters and no HR... :innocent:

Nope...IMHO, HR is redundant if you've got a PM.

After all, HR isn't a measure of the effort/load, it's a measure of a response to the effort/load...and a highly damped one as well. Not to mention the myriad of other things that can adversely affect HR one way or the other.

It seems to me that power and PE together work pretty well without any other "measures" :thumb:

That said, HR is better than nothing if you don't have a PM, at least for long, steady-state efforts.

umd 12-03-08 11:50 AM

Quote:

Originally Posted by tanhalt (Post 7956642)
Nope...IMHO, HR is redundant if you've got a PM.

After all, HR isn't a measure of the effort/load, it's a measure of a response to the effort/load...and a highly damped one as well. Not to mention the myriad of other things that can adversely affect HR one way or the other.

It seems to me that power and PE together work pretty well without any other "measures" :thumb:

That said, HR is better than nothing if you don't have a PM, at least for long, steady-state efforts.

I was just giving you a hard time about the 4 PMs. Did you end up taking the Polar or the iBike off?

kudude 12-03-08 11:50 AM

Quote:

Originally Posted by waterrockets (Post 7956526)
+1 to 5s power averaging.

I assume you choose to display on a 5s rolling average, but store data for each second. correct?

ZeCanon 12-03-08 12:48 PM

yep

tanhalt 12-03-08 01:10 PM

Quote:

Originally Posted by kudude (Post 7956679)
I assume you choose to display on a 5s rolling average, but store data for each second. correct?

Yes...the nice thing is that they are separately selectable.

Technically, the minimum sample rate on the PT is 1.26s and that's the best rate to use (if you aren't "memory limited" for the ride at hand) because selecting anything longer ends up in data being "thrown away" since the PT head unit will just store whatever happened in the last 1.26s before it stores...otherwise known as "downsampling"...not good :notamused:

bdcheung 12-03-08 01:13 PM

I still wear a HR strap, because i'm a data junkie. Plus when I preach about power meters to my teammates I can show them the graph and say "See how my HR goes up over the course of my 1-hr SST session, but power remains constant? If I was training based on HR alone, I'd be way under-doing it in the last half of the interval!"

tanhalt 12-03-08 01:13 PM

Quote:

Originally Posted by umd (Post 7956677)
I was just giving you a hard time about the 4 PMs. Did you end up taking the Polar or the iBike off?

I know ;)

The Polar is close to coming off since it's not telling me anything I don't know already about it, or about the other PMs...however, I promised one of the guys at Velocomp that I'd throw him a sample Polar output on a trainer to show how "flaky" it can be. The interest is if one could still use a Polar to "calibrate" an iBike for "trainer mode" despite the flakiness.... hmmm, maybe I'll do that at lunchtime today since I decided to take an "easy day"...then I can finally take that off.

My bike will suddenly be 1/2 lb lower weight :)

kudude 12-03-08 01:19 PM

Quote:

Originally Posted by tanhalt (Post 7957164)
Yes...the nice thing is that they are separately selectable.

Technically, the minimum sample rate on the PT is 1.26s and that's the best rate to use (if you aren't "memory limited" for the ride at hand) because selecting anything longer ends up in data being "thrown away" since the PT head unit will just store whatever happened in the last 1.26s before it stores...otherwise known as "downsampling"...not good :notamused:

i prefer to downsample in post-processing. throwing away data should be a choice that you can reverse

ridethecliche 12-03-08 01:49 PM

I'm pretty sure I have my SRM set at 1 second intervals. I'll download data after every ride or two and since most of my rides aren't longer than 2-3 hours, the 6 hour setup works well.

I do need to go back and read the manual since I kept going into interval mode while trying to calibrate it yesterday. I couldn't get out of interval mode, so I just kept pressing buttons till something else happened haha.

challaday 12-03-08 10:37 PM

OK, I just got my powertap two days ago. I purchased the Allen & Coggan book about a month ago and read it cover-to-cover. So tonight I did the test from Chapter 3 on Functional Threshold Power, and I would like to make sure that I'm on the right track.

I followed their instructions religiously by taping a small guide on my handlebars while on my Kurt Kinetic trainer. I did the warmup as they proscribe, and then the 20 minute time trial. Oh, and if it matters, yesterday was my "rest" day and I did about an hour's worth of light spinning.

After downloading the data, the 20 minute time trial average power was 263.2 watts. According to the book, that means that 95% of that number, or 250.04 is my FTP. Since I weigh 155 pounds, or 70kg, that means my wkg value at FTP is 3.57

Does this sound like the right methodology and conclusion? Is doing the TT on the trainer good or bad?

ridethecliche 12-03-08 11:18 PM

Quote:

Originally Posted by challaday (Post 7960896)
OK, I just got my powertap two days ago. I purchased the Allen & Coggan book about a month ago and read it cover-to-cover. So tonight I did the test from Chapter 3 on Functional Threshold Power, and I would like to make sure that I'm on the right track.

I followed their instructions religiously by taping a small guide on my handlebars while on my Kurt Kinetic trainer. I did the warmup as they proscribe, and then the 20 minute time trial. Oh, and if it matters, yesterday was my "rest" day and I did about an hour's worth of light spinning.

After downloading the data, the 20 minute time trial average power was 263.2 watts. According to the book, that means that 95% of that number, or 250.04 is my FTP. Since I weigh 155 pounds, or 70kg, that means my wkg value at FTP is 3.57

Does this sound like the right methodology and conclusion? Is doing the TT on the trainer good or bad?

I think you're on the right track. If you do the test on the trainer, make sure you repeat it on the trainer everytime to exclude outside variables. Personally, I think testing on the trainer is the way to go.

Also, I would do a MAP test and see if your 20 minute interval falls in the range of 72-78% of MAP. Use it as a check.

Heh, your FTP and W/KG is right around mine. I'm ~68Kg.

waterrockets 12-03-08 11:19 PM

95% is a very rough estimate.

On the trainer, you will likely be a little underpowered because of the inertial effects on your pedal stroke.

So, figure +/- 5% on the 95% number, and +/- 10% on the trainer effect, and you're at +/- 15%.

Just go train for a while and see what the numbers are showing you.

ridethecliche 12-03-08 11:26 PM

Quote:

Originally Posted by waterrockets (Post 7961210)
95% is a very rough estimate.

On the trainer, you will likely be a little underpowered because of the inertial effects on your pedal stroke.

So, figure +/- 5% on the 95% number, and +/- 10% on the trainer effect, and you're at +/- 15%.

Just go train for a while and see what the numbers are showing you.

Hm. I'm a little perplexed. I was under the impression that your seated W/Kg on a trainer would be higher since you're meeting resistance in every part of the pedal stroke and you can't 'con' your way out of your dead spot as easily as you can on the road.

When standing this isn't the case since you can't really move the bike under you and this generates power.

umd 12-03-08 11:42 PM

Quote:

Originally Posted by ridethecliche (Post 7961253)
Hm. I'm a little perplexed. I was under the impression that your seated W/Kg on a trainer would be higher since you're meeting resistance in every part of the pedal stroke and you can't 'con' your way out of your dead spot as easily as you can on the road.

When standing this isn't the case since you can't really move the bike under you and this generates power.

I can't get as much power on the trainer, seated or otherwise.

ridethecliche 12-04-08 12:16 AM

Quote:

Originally Posted by umd (Post 7961351)
I can't get as much power on the trainer, seated or otherwise.

Why do you think this is?

Is my logic reversed? Are we forced to spend more time in our deadspot while on the trainer?

This would reduce power during the dead spot, force more time there, and decrease average power.

ZeCanon 12-04-08 12:20 AM

I would attribute it to having nothing else to think about but my legs hurting.

At least outside I have to use some brain power to not fall over.

ridethecliche 12-04-08 01:01 AM

Quote:

Originally Posted by ZeCanon (Post 7961498)
I would attribute it to having nothing else to think about but my legs hurting.

At least outside I have to use some brain power to not fall over.

LOL!

I watch movies or blast movies while on the trainer. I actually don't mind riding the trainer while doing that. 1 hour max (with intervals) if just listening to music. I can go for 1.5+ hours if I'm watching a race, show, movie, whatever.

waterrockets 12-04-08 01:12 AM

I think it has to do with the inertial differences between the road and the trainer. If you stop pedaling on the trainer, it doesn't take long to come to a complete stop. On the road, it takes a really long time. So, on the trainer, the dead part of your stroke (with reduced power) is going to decelerate more than on the road.

This means that you're spending energy accelerating the wheel more with each pedal stroke, which means that your normal applied torque will be multiplied by a lower angular velocity on the crank or the wheel, until you get back up to speed during the stroke. Lower angular velocity means less power.

ridethecliche 12-04-08 01:34 AM

Quote:

Originally Posted by waterrockets (Post 7961626)
I think it has to do with the inertial differences between the road and the trainer. If you stop pedaling on the trainer, it doesn't take long to come to a complete stop. On the road, it takes a really long time. So, on the trainer, the dead part of your stroke (with reduced power) is going to decelerate more than on the road.

This means that you're spending energy accelerating the wheel more with each pedal stroke, which means that your normal applied torque will be multiplied by a lower angular velocity on the crank or the wheel, until you get back up to speed during the stroke. Lower angular velocity means less power.

That's basically what I was trying to say less elegantly. Thanks WR!

mista_chewey 12-04-08 03:53 AM

so basically those ftp tests are just testing your power in a 20minute time frame?
gotta go try that....

ljrichar 12-04-08 06:48 AM

Quote:

Originally Posted by mista_chewey (Post 7961806)
so basically those ftp tests are just testing your power in a 20minute time frame?
gotta go try that....

Not exactly. FTP is the power you can hold for a 60min time trial. That is why they were taking 95% of the 20min time as an estimate of FTP.

sgrundy 12-04-08 07:30 AM

Quote:

Originally Posted by waterrockets (Post 7961626)
I think it has to do with the inertial differences between the road and the trainer. If you stop pedaling on the trainer, it doesn't take long to come to a complete stop. On the road, it takes a really long time. So, on the trainer, the dead part of your stroke (with reduced power) is going to decelerate more than on the road.

This means that you're spending energy accelerating the wheel more with each pedal stroke, which means that your normal applied torque will be multiplied by a lower angular velocity on the crank or the wheel, until you get back up to speed during the stroke. Lower angular velocity means less power.

That's part of it. The other part is that it can be hard to stay cool indoors. If you have a trainer with a massive flywheel and a huge fan nearby you might actually be able to exceed the power that you can generate outdoors. However, I've read that after a few weeks of adapting to the trainer indoor and outdoor power numbers start to converge, so if you're on the trainer a lot there might not be a significant difference.

waterrockets 12-04-08 10:12 AM

Quote:

Originally Posted by sgrundy (Post 7962186)
That's part of it. The other part is that it can be hard to stay cool indoors. If you have a trainer with a massive flywheel and a huge fan nearby you might actually be able to exceed the power that you can generate outdoors. However, I've read that after a few weeks of adapting to the trainer indoor and outdoor power numbers start to converge, so if you're on the trainer a lot there might not be a significant difference.

yep

Psimet2001 12-04-08 10:14 AM

Watt?

fuzzthebee 12-04-08 10:39 AM

Quote:

Originally Posted by challaday (Post 7960896)
OK, I just got my powertap two days ago. I purchased the Allen & Coggan book about a month ago and read it cover-to-cover. So tonight I did the test from Chapter 3 on Functional Threshold Power, and I would like to make sure that I'm on the right track.

I followed their instructions religiously by taping a small guide on my handlebars while on my Kurt Kinetic trainer. I did the warmup as they proscribe, and then the 20 minute time trial. Oh, and if it matters, yesterday was my "rest" day and I did about an hour's worth of light spinning.

After downloading the data, the 20 minute time trial average power was 263.2 watts. According to the book, that means that 95% of that number, or 250.04 is my FTP. Since I weigh 155 pounds, or 70kg, that means my wkg value at FTP is 3.57

Does this sound like the right methodology and conclusion? Is doing the TT on the trainer good or bad?

You might want to round off your power numbers. Power meters are not that precise, and niether is estimating FTP.


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