IDT with PowerTap

[Marius]

I want to know, when you use a PowerTap on a IDT will there be a difrence in power output depending on how much friction there is where the wheel makes contact with the IDT tyre resting area.

Surly it should not, if you pedall harder / have more resistance the power will be more and when you pedal softer or the resistance is less the power will be less.

 

SO then, if tha tis true, the resistance does not matter right?

 

Sooo, then weight also don't play a part or does it? I mean, sure, if you are big you are going to pruduce more power and if you are small there will be less.

 

I've been told to add 15% to my IDT power to get closer to real road value's, but when I do that the power looks a bit high, too high, I don't get those kind of power on the road, so now what?

 

What kinda experciance do you guys have?

[TitusTi]

When I ride indoor power seems alot lower than outdoors, I think it's a motivational thing. Hate riding indoors!

[BikeMax]

 

You are correct - the power tap measures output so resistance is only relevant in that it will increase or decrease power generally (like climing a hill or riding into the wind)

 

The only reason you would add resistance is to vary the cadence or to make it easier to generate the power you want to train at.

 

Weight is also not a factor on the IDT.

 

The only reason you may have been advised to vary the power values on an IDT is that many folks have a problem matching their outdoor power when on the IDT (There are a few theories about why that don't matter too much here)

 

I would suggest that you test on the trainer and then compare to outdoor power - then you can adjust zones accordingly (if you need to)

 

For what it's worth most people find the difference gets smaller the more they ride the trainer and adjust to it.

 

BikeMax2007-08-24 07:14:27

[Marius]

"a lot", would you say 15% less, that's what I add to get "Road Power" or whould you say 15% is to high??

 

The thing is I've AV'ed about 238Watts on the road on Wedensday and then yesterday I AV'ed 238Watts on the IDT, surly I can't add 15% to that cuz I have never gotten a Av Power that high..

[BikeMax]

 

"a lot"' date=' would you say 15% less, that's what I add to get "Road Power" or whould you say 15% is to high??

 

The thing is I've AV'ed about 238Watts on the road on Wedensday and then yesterday I AV'ed 238Watts on the IDT, surly I can't add 15% to that cuz I have never gotten a Av Power that high..

[/quote']

 

Test on both - then you will know.

 

[Marius]

Thx BikeMax, then I would have to agree on that last point, seems like it don't make much of a difference to me anymore, since I?m getting the same power output both in and out doors, damn...thought I was getting better

[bruce]

Agree with Bikemax - I see a significant variance between different athletes on idt and outdoor.  Some guys are 15% higher outdoors than indoors, I am around 8%.  Spoke to Marco van Biljoen yesterday and he reckons he can't produce the same power on the road as he can on the indoor, eish - I feel sorry for his idt!!

 

So, do a threshold test in both environments.  If the difference is greater than about 5% I would say create a separate user in Cyclingpeaks with your indoor threshold and upload your indoor session to that user.  Then manually create a workout in your normal user and adjust the TSS so it matches your indoor workout - then your Performance Manager Chart stay accurate.

[Marius]

damn...that sounds like a lot of work bruce... can't a just fool myself by just adding 15% on the idt, I always feel so proud after a session on the IDT and adding the 15% it keeps me motivated!!

 

The other massive thing I have seen on the IDT is that on Tuesday I trained on the IDT with the door closed and the fan off, was doing4mins intervals at L5, my HR reached the 180bpm after the 4th interval and on the 5th I was finished. The last night I had the fan on full blast, door open, blinds open, shirt off and I did 9 intervals and never went over 173bpm, that's amazing right!?!??!

 

[Marius]

Now that I think of it, wtf!?!? You can't work it out...well you can, if you only use your IDT at the same temp it'll be constant, but if like me you for get to switch the Fan on and do it shirtless you gonna hit a higher HR and lower Power or at least not be able to sustain the same power for so long...my my word..

 

eg. same workout at diff temps, 208W / 238W, that's a massive differance.

Marius2007-08-24 08:01:02

[bruce]

Now that I think of it' date=' wtf!?!? You can't work it out...well you can, if you only use your IDT at the same temp it'll be constant, but if like me you for get to switch the Fan on and do it shirtless you gonna hit a higher HR and lower Power or at least not be able to sustain the same power for so long...my my word..

 

eg. same workout at diff temps, 208W / 238W, that's a massive differance.

[/quote']

 

Blood has multiple functions in the body:

Carry oxygen to the working muscles/organs.

Carry nutrients and fluid to the muscles/organs.

Remove waste products.

Act as a coolant.

So, when you get hot, blood is diverted to the surface vessels of the body as a heat exchange mechanism.  Thus the working muscles get a reduced supply of oxygen and hence cannot produce the same amount of power for the same HR - because the heart is now pumping coolant around.

If is because of these multiple functions of the blood that all of these factors (core temp, hydration, hunger, etc) affect the HR vs. power curve.

[Marius]

thx Bruce, i always thought it had less of a effect on Power / HR, but now I could see it.

[Marius]

Something else that's now starting to bug me Bruce. I feel like I'm cheating when I use the Fan on me. The reason I'm saying that is I'm now able to give a higher Power Output at a much lower HR.

So my Quistion is, what is better training;

 

A)Training at Higher Power Output with lower HR

B)Training at Higher HR with lower PO?

 

THX

[Brakkies Sport Fotos]

A... Than you get strongerpopeye2007-09-06 01:31:41

[fandacious]

depends what your goals are.. power or LT training?

[Marius]

hahaha, you guys are like SOOOOO not helping. Each workout is over the same time eg 1h30. Soooo my HRM says I'm buring less kj and my PM says I'm buring more kj with the fan, the oppiside is true if the fans off. So it seems like they are contrdicting each other, either I'm buring more or Less, I can't be buring the same amount of kj's, do I make sense?

[Brakkies Sport Fotos]

hey, praat afrikaans met my. Jy sit met jou gat in 'n saal vir 1h30.

 

so, hoe spandeer ek daai tyd om die beste opbrengs te kry.?

 

**** ek sal laaik om 'n lae hartrate te he, met baie krag.

 

so: "A" is die antwoord.