Wattage for a 40km/h TT??

[woodie]

Just wondering if anyone has real life power data from a 40 KK TT which was done in less than an hour? (on the road not the track).
There are plenty of calculators around to estimate the required wattage but then you need to know rolling resistance and aerodynamic resistance etc. I'd be interested to know from anyone's actual data, if they have riden 40K in under hour, the following info:
- Normalised Power,
- Weight,
- Bike setup; and
- General comments about the course.
Thanks.

Try this link.

http://bikecalculator.com/wattsMetric.html

Not 100% accurate but it might give you an idea. You can change what it calculates down the right hand side with the red text.

 

[biketechreview.com]

So you disagree that an increase in intensity is not linearly (or is curvilinearly) related to the physiological cost?

I'd suggest you google "normanalized power" for some old discussions on my views/beliefs of the topic. In short, I believe this when it comes to training:

1)raise the left
2)fill the right
3)scatter the plot
4)run whatchya brung
5)have fun

Where in that thread do I suggest that I market this as a commercial offering? I've provided all my thoughts on this to the public domain.

you used a GP derivative as a marketing tool in support of a business venture. if you have no commercial interests as you claim, then, you should just post your final spreadsheet and give it away to the public.

 

[Tapeworm]

you used a GP derivative as a marketing tool in support of a business venture. if you have no commercial interests as you claim, then, you should just post your final spreadsheet and give it away to the public.

Says the person who suggests a google search which leads to their forum. Get paid by the "click"? Hypocrisy much?

 

[biketechreview.com]

Says the person who suggests a google search which leads to their forum. Get paid by the "click"? Hypocrisy much?

Like I said previously (perhaps you missed it?), I run a for profit website. I make no money when you do a google search for "normanalized power" and click on the links that are served...if you prefer, I can provide a direct link to the thread, but don't know "the rulez" around here about that sort of thing. I was actually acting on the side of caution...but, it seems you've dug your heels in on this which is interesting.

 

[Tapeworm]

I find it interesting that you've had a crack at a regular and informative poster for no real reason I can ascertain.

 

[Alex Simmons/RST]

I find it interesting that you've had a crack at a regular and informative poster for no real reason I can ascertain.

All's fair in love 'n' war.

Mr Willett and I agree on 99% of stuff I'd say and he provides many useful insights himself, many of which are freely available, some you have to pay for.

Like him, I enjoy pithy statements that try to encapsulate the essence of bike riding. And like him I also enjoy getting deep under the skin of performance factors to understand why those statements are generally pretty well on the mark.

He doesn't like the concept of Normalised Power (either from a physiological basis and/or a commercial one) but I find it provides additional insight into what's going on. That's one point of difference.

He has his own forum, and chooses to use word substitution for terms like Normalised Power. His forum, he can make his own rules. I choose to not like that as it makes no real sense to me.

 

[microdose]

has anyone answered your question? i see a lot of numbers.

there has been some semi-useful info....

 

[microdose]

Try this link.

http://bikecalculator.com/wattsMetric.html

Not 100% accurate but it might give you an idea. You can change what it calculates down the right hand side with the red text.

Thanks. I have used a few calculators before and I guess the big problem I have had is trying to estimate how "aero" I am. That's why I made the post to try and get some indicative feedback of "real world" numbers. Looking at this calculator it gives 56 W difference between the position of "Drops" to Aerobar" for my scenario. Even though I am using TT bars I think my position is not very good, I probably look worse than Andy Schleck.... so my required power output is closer to the "drops" position than it should be.

 

[oldborn]

there has been some semi-useful info....

Dude just ride damn bike, don t look at the numbers while you ride it and try to overcome the pain. You will hit wats eventually. Everything else is just some helpful tools, but we can still train future TT champion of the world without power meter for sure.

 

[Tapeworm]

But doing things such as working out cda testing are an excellent way to use the powermeter which MAY result in better returns for your effort (Google "Chung method").

 

[oldborn]

But doing things such as working out cda testing are an excellent way to use the powermeter which MAY result in better returns for your effort (Google "Chung method").

Off course Tapeworm it can help in a non-phycical way, more in technical science way. Still engine, legs and hard work is key element.

 

[Tapeworm]

Aye, and as mentioned there have been many a champion without a watt reading in sight (and will be many more). BUT there is a reason why their prevalence is increasing, my above reasons notwithstanding. As price goes down and availability increases of PMs we'll see more of these no doubt.

 

[Alex Simmons/RST]

Off course Tapeworm it can help in a non-phycical way, more in technical science way. Still engine, legs and hard work is key element.

There's nothing wrong with adding intelligence to that mix.

 

[Alex Simmons/RST]

For the OP:

To ride at 40km/h on a reasonable surface dead flat road with good tyres (Crr of 0.0045) on a dead calm day with average air density, then you'll need a power to aero drag ratio (W/CdA) of around 950 W/m^2 or more.

For example, if you know you can sustain 260W for an hour, then to ride the 40km in an hour you'll need a CdA of 260/950 = 0.27 m^2 or less.

Of course if the road varies in gradient and/or there is wind, then the overall W/m^2 required to break 1 hour will go up.

If it is very hilly and or steep, then the power to weight ratio (W/kg) of the rider will also being to impact the power required to break an hour for 40km.

In terms of how does a CdA of 0.27m^2 rate?

Well anything under 0.20 is very slick. Lowest I've measured is ~0.18m^2.
0.20-0.22 is pretty slick
0.22-0.28 is the sort of range I see most TT riders fall into, lower means they've paid attention to details and/or are smaller
0.25-0.32 is more normal on track bike mass start set up, smaller riders will be at lower end
0.32 and up and you are on your road bike, but smaller guys can be less of course

much depends on many factors, morphology, position, equipment etc etc

 

[will10]

Out of interest Alex, who was the ~0.18m^2 rider? Was it the rider you coached to that Masters hour record?

 

[microdose]

For the OP:

To ride at 40km/h on a reasonable surface dead flat road with good tyres (Crr of 0.0045) on a dead calm day with average air density, then you'll need a power to aero drag ratio (W/CdA) of around 950 W/m^2 or more.

For example, if you know you can sustain 260W for an hour, then to ride the 40km in an hour you'll need a CdA of 260/950 = 0.27 m^2 or less.

Of course if the road varies in gradient and/or there is wind, then the overall W/m^2 required to break 1 hour will go up.

If it is very hilly and or steep, then the power to weight ratio (W/kg) of the rider will also being to impact the power required to break an hour for 40km.

In terms of how does a CdA of 0.27m^2 rate?

Well anything under 0.20 is very slick. Lowest I've measured is ~0.18m^2.
0.20-0.22 is pretty slick
0.22-0.28 is the sort of range I see most TT riders fall into, lower means they've paid attention to details and/or are smaller
0.25-0.32 is more normal on track bike mass start set up, smaller riders will be at lower end
0.32 and up and you are on your road bike, but smaller guys can be less of course

much depends on many factors, morphology, position, equipment etc etc

Thanks Alex - I appreciate that info. As I am 185 cm and do not have good flexibility I think my current position probably puts me near the 0.28 - 0.32 range, but I intend to do some testing to try and gain a good estimate.

 

[oldborn]

There's nothing wrong with adding intelligence to that mix.

Off course

 

[Alex Simmons/RST]

Out of interest Alex, who was the ~0.18m^2 rider? Was it the rider you coached to that Masters hour record?

Two riders actually. Jayson was ~ 0.185 m^2 for his hour record but can be less for shorter efforts (we needed to address some comfort issues for the hour). And a female rider that I don't coach that's even a little less again.

I vaguely recall Levi Leipheimer being in the vicinity of 0.20 m^2, but I could be wrong.

 

[Oldman]

Dude just ride damn bike, don t look at the numbers while you ride it and try to overcome the pain. You will hit wats eventually. Everything else is just some helpful tools, but we can still train future TT champion of the world without power meter for sure.

And I think you'll find Mr. Willett did just that until he hit the point of fitness to actually apply aero and wattage principles. Most important: if it's not fun you won't do it well. Personally I think you move from that perspective in your drops to the next ergo/aero transition that feels more comfortable. Refinements can come from your own input if you pay attention to other riders and watch some serious time trial vids.

 

[oldborn]

And I think you'll find Mr. Willett did just that until he hit the point of fitness to actually apply aero and wattage principles..

Who is Mr. Willett?

Most important: if it's not fun you won't do it well...

I agree. Ego orientation vs. Task orientation

Personally I think you move from that perspective in your drops to the next ergo/aero transition that feels more comfortable.

I don t understand it at all

 

[Oldman]

Who is Mr. Willett?


I agree. Ego orientation vs. Task orientation


I don t understand it at all

Kraig Willett/Biketech. He's been a genius of aerodynamics for some time.

The last part: ride some TT's in your drops until you're comfortable with your fitness, then start adding the aero components. You'll translate the ergonomic comfort better and not make any drastically uncomfortable adjustments. If you can't ride a 40k in under an hour on your road bike you don't need to fret too much about wattage output at this point.

 

[oldborn]

Kraig Willett/Biketech. He's been a genius of aerodynamics for some time.

I did not knew his real name, thanks.

The last part: ride some TT's in your drops until you're comfortable with your fitness, then start adding the aero components. You'll translate the ergonomic comfort better and not make any drastically uncomfortable adjustments. If you can't ride a 40k in under an hour on your road bike you don't need to fret too much about wattage output at this point.

I got it now

 

[FrankDay]

What is very interesting there is the aero helmet only worth 3 watts. I have often heard it said the helmet is the best bang for buck around (that may still be true) and in watts nearly as good as a aero wheel. This shows a skinsuit getting 3 times the gain of a helmet.
The power required also suggests that having a high seat angle may be counter productive towards getting the best aero. Pushing the seat back and lowering the effective seat angle was a big gain.

I think the value of the aero helmet depends upon where the head is in relation to the body. If it is up above everything else looking down the road, then it will make a big difference. If it is tucked down and the rider is only looking 10-20m up the road (or the front so low the head is lower that the top of the back) then the aero helmet will probably add little. Since the aero helmet was added late in this cascade we might assume the later condition accounting for the small improvement.