Online Power Verification



Doctor Morbius

New Member
Mar 15, 2004
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Could any of you power meter users verify the accuracy of this online PM calculator?

http://www.kreuzotter.de/english/espeed.htm

Yes, I know it's not Analytical Cycling but this one is much easier to use, i.e. I don't have to know my frontal area or do english to metric conversions or know my miles per second under Speed. Who does miles per second anyway? Anybody really track that one? :confused: Basically, if it comes to having to do all of the conversions each time I want to use the calc, I'm not going to use it.

Anyway, if any of you could plug in a couple of different speeds that you ride and verify the wattage and post back that would be excellent. Thanks in advance.
 

RapDaddyo

Well-Known Member
May 17, 2005
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Doctor Morbius said:
Who does miles per second anyway?
Hmmm. Since the SR-71 was only capable of ~1500mph, I suppose I'd have to say Space Shuttle Drivers. Do you think they have a stationery bike up there for exercise?
 

ric_stern/RST

New Member
Nov 11, 2002
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Hurstpierpoint
www.cyclecoach.com
Doctor Morbius said:
Could any of you power meter users verify the accuracy of this online PM calculator?

http://www.kreuzotter.de/english/espeed.htm

Yes, I know it's not Analytical Cycling but this one is much easier to use, i.e. I don't have to know my frontal area or do english to metric conversions or know my miles per second under Speed. Who does miles per second anyway? Anybody really track that one? :confused: Basically, if it comes to having to do all of the conversions each time I want to use the calc, I'm not going to use it.

Anyway, if any of you could plug in a couple of different speeds that you ride and verify the wattage and post back that would be excellent. Thanks in advance.

Erm... the measure on AC.com that i *think* you are talking about is metres per second (m/s) not miles per second. Just divide km/hr by 3.6 to convert your speed.

ric
 

Doctor Morbius

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Mar 15, 2004
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I guess I should have caught that one but I never use the metric system. The only reason we use it in the States is to convert everything to English units.

So no feedback on the calculator? Bummer.
 

RapDaddyo

Well-Known Member
May 17, 2005
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Doctor Morbius said:
I guess I should have caught that one but I never use the metric system. The only reason we use it in the States is to convert everything to English units.

So no feedback on the calculator? Bummer.
I took a quick look at the calculator, Dr. M. I like it. I haven't check the formulae to see what it is doing with the built-in factors such as hands on the hoods vs. on the drops, but I like the idea of a simple set of real-world choices vs. deriving something that most of us don't know such as our frontal area. I sort of wish they had a drop-down list for wheels. I'm working on a TT pacing model and other "secret" weapons. I may take this approach in my model -- a checklist rather than plugging in numbers. I took a quick look at some of the computed speeds at powers that I regularly ride at and they looked reasonable. The basic problem is that we're almost never riding on the flat with no wind and we basically never know the actual wind but only what the weather service says the winds are. I'm still in shock having looked at some of my daily rides and comparing my "perception" of grades with actual grades from my DeLorme topo software. I now know that I don't "see" grades very accurately.
 

Squint

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Jul 27, 2003
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I just started playing with Topo and lo and behold, the switchbacks at 7000+ feet where it takes 300W standing and in my lowest gear to go 8.5 mph are 33% grade according to Topo. :)
 

ric_stern/RST

New Member
Nov 11, 2002
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Doctor Morbius said:
I guess I should have caught that one but I never use the metric system. The only reason we use it in the States is to convert everything to English units.

So no feedback on the calculator? Bummer.


It always surprises me that such a technologically advanced country as the States, still uses incorrect and outdated measures.

Not had a chance to look at the calculator yet. maybe tomorrow.

ric
 

Doctor Morbius

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Mar 15, 2004
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ric_stern/RST said:
It always surprises me that such a technologically advanced country as the States, still uses incorrect and outdated measures.

Not had a chance to look at the calculator yet. maybe tomorrow.

ric
:D Well you Brits invented the damned system. Why argue with a tiny island that ruled the world for 500 years? If you ask me you guys should be dictating terms to the EU and not the other way around.
 

Doctor Morbius

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Mar 15, 2004
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RapDaddyo said:
I took a quick look at the calculator, Dr. M. I like it. I haven't check the formulae to see what it is doing with the built-in factors such as hands on the hoods vs. on the drops, but I like the idea of a simple set of real-world choices vs. deriving something that most of us don't know such as our frontal area. I sort of wish they had a drop-down list for wheels. I'm working on a TT pacing model and other "secret" weapons. I may take this approach in my model -- a checklist rather than plugging in numbers. I took a quick look at some of the computed speeds at powers that I regularly ride at and they looked reasonable. The basic problem is that we're almost never riding on the flat with no wind and we basically never know the actual wind but only what the weather service says the winds are. I'm still in shock having looked at some of my daily rides and comparing my "perception" of grades with actual grades from my DeLorme topo software. I now know that I don't "see" grades very accurately.
There seems to be quite a difference (at least in my case) between on the hoods vs. on the drops. I don't know how accurate any of it is but I thought it may better represent a "layman's" calc than the one at analytic cycling. With any online calc items such as wind resistance and climbing can only be estimated against the real world.
 

RapDaddyo

Well-Known Member
May 17, 2005
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ric_stern/RST said:
It always surprises me that such a technologically advanced country as the States, still uses incorrect and outdated measures.

Not had a chance to look at the calculator yet. maybe tomorrow.

ric
It always surprises me that such a socially advanced country as England still has a King. I guess you're stuck with your castles and we're stuck with our inches.
 

ric_stern/RST

New Member
Nov 11, 2002
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RapDaddyo said:
It always surprises me that such a socially advanced country as England still has a King. I guess you're stuck with your castles and we're stuck with our inches.

We have a queen! Been a good few years since we had a king... before i was born!

lots of castles though, there's one just a few hundred metres (or a few hundred yards ;) :D ) from where i am now!
 

jjjtttggg

New Member
Sep 3, 2003
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Doctor Morbius said:
Could any of you power meter users verify the accuracy of this online PM calculator?

http://www.kreuzotter.de/english/espeed.htm

Yes, I know it's not Analytical Cycling but this one is much easier to use, i.e. I don't have to know my frontal area or do english to metric conversions or know my miles per second under Speed. Who does miles per second anyway? Anybody really track that one? :confused: Basically, if it comes to having to do all of the conversions each time I want to use the calc, I'm not going to use it.

Anyway, if any of you could plug in a couple of different speeds that you ride and verify the wattage and post back that would be excellent. Thanks in advance.

I use the kreuzotter calculator, too. I like it because it's really easy. Like you Dr. M, I have no way to know whether it is accurate or not. I can point to one disconnect, though, but not necessarily with the calculator. Based on the calculator and my riding, I can maintain about 250W - 260W for 20min. I weigh 80kG. According to a table I saw somewhere here (can't find the thread now, but its similar to this one
http://www.cyclingpeakssoftware.com...rprofile_v3.gif,
but with Racing categories on the left hand side), that should put me near the upper end of Cat 5 riders and lower end of Cat 4. Well last weekend I rode a Cat 5 race - ugly! I was at the end of that group all right, but it wasn't the upper end I'm sad to say. So. . . either 1.) Really fast Cat 5 group, 2.) Power/kg table no good, 3.) Nothing more than a bit of an off day for Mr. J (Hey, could be!), or 4.) Kreuzotter calculator no good.

I will say this, the calculator has yielded fairly consistent power numbers over a fairly wide range of conditions for a given range of percieved effort and HR data. I feel like it's pretty good.

J
 

danch

New Member
Aug 5, 2004
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ric_stern/RST said:
It always surprises me that such a technologically advanced country as the States, still uses incorrect and outdated measures.

Not had a chance to look at the calculator yet. maybe tomorrow.

ric
Hey, we like making our math more difficult! Builds character!
 

danch

New Member
Aug 5, 2004
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RapDaddyo said:
Hmmm. Since the SR-71 was only capable of ~1500mph, I suppose I'd have to say Space Shuttle Drivers. Do you think they have a stationery bike up there for exercise?
I believe they do, actually!
 

RapDaddyo

Well-Known Member
May 17, 2005
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ric_stern/RST said:
Do you need a diagram to show the differences between men and women? ;) :eek:
Oh, I'm not referring to gender. I mean they're both expensive and worthless.
 

RapDaddyo

Well-Known Member
May 17, 2005
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ric_stern/RST said:
Phew! that's a relief. i'd have been worried if you didn't know the difference at your age ;)
Yep. I've had the physical differences figured out for at least a couple of years now. As to the behavioral differences, I've given up trying to figure it out.