so what about cadence

[coapman]

cadence and pedaling rate are the same thing and they simply represent the frequency the muscles must both contract and relax. Pedal speed is the linear speed of the pedal and determines the necessary velocity of the muscle contraction before any force can be applied to the pedal. Pedal speed can be calculated if one knows both crank length and cadence.

How is the knowledge gained from this research supposed to assist a cyclist in improving performance

 

[FrankDay]

How is the knowledge gained from this research supposed to assist a cyclist in improving performance

How? I suppose most would call it "thinking" about it then "applying" the new knowledge to the real world. How does any new information eventually result in improvements in any field of work?

 

[coapman]

How? I suppose most would call it "thinking" about it then "applying" the new knowledge to the real world. How does any new information eventually result in improvements in any field of work?

You mean it's like the clutter some people collect in their homes, it might come in useful some day. I've already spotted a flaw in this research and JayKosta should also be able to spot it.

 

[JayKosta]

You mean it's like the clutter some people collect in their homes, it might come in useful some day. I've already spotted a flaw in this research and JayKosta should also be able to spot it.

--------------------------------
Well yes, some research does only result in a collection of information that doesn't seem to have any immediate usefulness.

I haven't looked deeply into the Power/Pedal Speed research because I don't have a copy of the full-text. If there is something specific that you would like to discuss, please include the full quoted text from the report or abstract that you find faulty, and explain your concerns - we can proceed from there.

Jay Kosta
Endwell NY USA

 

[coapman]

--------------------------------
Well yes, some research does only result in a collection of information that doesn't seem to have any immediate usefulness.

I haven't looked deeply into the Power/Pedal Speed research because I don't have a copy of the full-text. If there is something specific that you would like to discuss, please include the full quoted text from the report or abstract that you find faulty, and explain your concerns - we can proceed from there.

Jay Kosta
Endwell NY USA

I know as much about this research as you do, the flaw I am referring to is connected to that " Dead Center Size " research.

 

[FrankDay]

I know as much about this research as you do, the flaw I am referring to is connected to that " Dead Center Size " research.

What you don't seem to realize is that all research has flaws. There is no such thing as a perfect study. The world is left, usually, reading between the lines, extrapolating, and combining the information of many different flawed studies to draw conclusions regarding their own particular situation. The fact that one can find a flaw in a study does not, per se, invalidate the study.

So, give us the details of the flaw you see and let's discuss how or whether this flaw affects any conclusions one might reasonably make from the study.

 

[coapman]

What you don't seem to realize is that all research has flaws. There is no such thing as a perfect study. The world is left, usually, reading between the lines, extrapolating, and combining the information of many different flawed studies to draw conclusions regarding their own particular situation. The fact that one can find a flaw in a study does not, per se, invalidate the study.

So, give us the details of the flaw you see and let's discuss how or whether this flaw affects any conclusions one might reasonably make from the study.

I am always seeking perfection. As JayKosta said, we have not seen the full text of this study, we only got the conclusions. Using a calculated pedal speed assumes the speed is constant, this is not so, there is continuous acceleration and deceleration around the pedaling circle.

 

[elapid]

I am always seeking perfection. As JayKosta said, we have not seen the full text of this study, we only got the conclusions. Using a calculated pedal speed assumes the speed is constant, this is not so, there is continuous acceleration and deceleration around the pedaling circle.

Acceleration and speed are different. Acceleration is the rate at which an object changes it's speed, and is calculated according to the following equation: acceleration = metres/speed^2.

Pedal speed does not change within the cycle of a pedal stroke because pedal speed is determined by cadence and crank length (pedal speed = 2 x pie x cadence x crank length/60). As cadence is dependent on completion of a full rotation of the crank, any difference in speed of the pedal during a single rotation will not be relevant in these calculations.

 

[FrankDay]

Acceleration and speed are different. Acceleration is the rate at which an object changes it's speed, and is calculated according to the following equation: acceleration = metres/speed^2.

Pedal speed does not change within the cycle of a pedal stroke because pedal speed is determined by cadence and crank length (pedal speed = 2 x pie x cadence x crank length/60). As cadence is dependent on completion of a full rotation of the crank, any difference in speed of the pedal during a single rotation will not be relevant in these calculations.

Ugh, pedal speed is always changing. Fortunately, pedal speed changes so little during a normal pedal stroke that it can be considered constant for most purposes. If it were not for that change in pedal speed the computrainer spinscan would not work as it depends upon the small change in wheel speed (which is directly related) to calculate the various pedal torques as the pedal moves around the circle.

And, the relevant equation is F=ma, where F is the difference between the pedal force (trying to speed the pedals up) and the wind/rolling resistance (trying to slow the pedal down). When the sum is positive the pedal accelerates, when it is negative it decelerates. And, right in between is the average speed of both the bike and the pedal for that rotation.

Edit: The computrainer is helped in its spinscan determination by the fact that when on the trainer the moving mass is small, being only the mass of the rotating rear wheel, so there is a larger variation in speed than when on the road where we have both the rotating mass of both wheels plus the moving mass of both the bike and the rider. Speed variation is quite small when riding on a bike but it is still there.

 

[elapid]

Ugh, pedal speed is always changing. Fortunately, pedal speed changes so little during a normal pedal stroke that it can be considered constant for most purposes.

Which is what I said here, Frank:

As cadence is dependent on completion of a full rotation of the crank, any difference in speed of the pedal during a single rotation will not be relevant in these calculations.

And, the relevant equation is F=ma

The relevant equation is

acceleration = metres/speed^2

when pointing out to coapman the difference between speed and acceleration when coapman was using these terms interchangeably.

 

[FrankDay]

Originally Posted by elapid View Post
acceleration = metres/speed^2

That "equation" you posted has no meaning to me. You meant to say acceleration = ds/dt, that is the change in speed per unit time, not distance/speed squared.

Anyhow, I agree that pedal speed variation is essentially zero for most purposes but it certainly is not trivial because, otherwise, it would be impossible for such things as spinscan to be calculated. That having been said your statement

Pedal speed does not change within the cycle of a pedal stroke

is simply wrong.

 

[elapid]

Comprehension, Frank, has always been one of your many weaknesses. That's not what I said and you know it. Stop misrepresenting and misquoting me.

 

[elapid]

That "equation" you posted has no meaning to me. You meant to say acceleration = ds/dt, that is the change in speed per unit time, not distance/speed squared.

Because it has no meaning to you does not mean it is incorrect, likely the opposite. Check any textbook or website you like.

 

[FrankDay]

Because it has no meaning to you does not mean it is incorrect, likely the opposite. Check any textbook or website you like.

Could you provide a link to just one?

 

[sciguy]

Could you provide a link to just one?

http://www.dummies.com/how-to/content/how-to-calculate-acceleration.html

I do however agree that there is a cyclic pattern of measurable micro accelerations of the foot within every typical pedal revolution.

Hugh

 

[FrankDay]

http://www.dummies.com/how-to/content/how-to-calculate-acceleration.html

I do however agree that there is a cyclic pattern of measurable micro accelerations of the foot within every typical pedal revolution.

Hugh

Thanks but the last I checked distance over time squared is not the same as distance over speed squared.

 

[JayKosta]

...
Anyhow, I agree that pedal speed variation is essentially zero for most purposes but it certainly is not trivial because, otherwise, it would be impossible for such things as spinscan to be calculated.
...

----------------------------------------
The basic definition of ACCELERATION is:
'amount of change in speed' PER 'change in time'

such as Meters-per-Second PER Second

And YES, the pedal speed variation is not trivial.
In addition to spinscan, it is also the cause of 'uncoupling' in independent cranks.

Jay Kosta
Endwell NY USA

 

[FrankDay]

----------------------------------------
The basic definition of ACCELERATION is:
'amount of change in speed' PER 'change in time'

such as Meters-per-Second PER Second

And YES, the pedal speed variation is not trivial.
In addition to spinscan, it is also the cause of 'uncoupling' in independent cranks.

Jay Kosta
Endwell NY USA

Actually, acceleration is the change in velocity per unit time. Velocity is a vector so it is possible to accelerate without changing speed, a scalar quantity, by changing direction while maintaining speed. For practical purposes we can use speed for this argument but to be perfectly correct we should be talking velocity.

Edit: And, it isn't this pedal speed variation that causes the uncoupling of independent cranks. That uncoupling occurs only when the forces are inadequate to accelerate the both pedals equally as the bike/wheel speed varies. The amount of force necessary to do this is quite small and for all practical purposes only occurs when the forward force on one of the pedals becomes zero (or negative) while the other is still positive.

 

[elapid]

Thanks but the last I checked distance over time squared is not the same as distance over speed squared.

Yep, my bad. Used speed (m/s) instead of seconds (s). Baby-induced sleep deprivation. Still doesn't change the fact that acceleration and speed are not the same thing.

 

[FrankDay]

Still doesn't change the fact that acceleration and speed are not the same thing.

I know you seem to think my reading comprehension is sub par but could I ask you to point me to the post where someone made the claim or statement that speed and acceleration were the same thing is? I, obviously, missed it.

 

[elapid]

I know you seem to think my reading comprehension is sub par but could I ask you to point me to the post where someone made the claim or statement that speed and acceleration were the same thing is? I, obviously, missed it.

See coapman's post #154. Coapman did not say they were the same thing, but he used speed and acceleration interchangeably as though they were the same thing.

 

[FrankDay]

See coapman's post #154. Coapman did not say they were the same thing, but he used speed and acceleration interchangeably as though they were the same thing.

I am always seeking perfection. As JayKosta said, we have not seen the full text of this study, we only got the conclusions. Using a calculated pedal speed assumes the speed is constant, this is not so, there is continuous acceleration and deceleration around the pedaling circle.

Wow, I don't read it that way at all. I actually agree with the pedal speed part of his statement in that pedal speed is essentially always changing because net pedal force is almost never equal to net resistance force so pedal speed is almost always either accelerating or decelerating. It is just that these changes are so small that the rider is unable to perceive them and so small it is reasonable to use a calculated average (constant) pedal speed for most practical purposes.

 

[coapman]

Pedal speed is the linear speed of the pedal and determines the necessary velocity of the muscle contraction before any force can be applied to the pedal.

You mean before any torque can be applied to the crank ? In natural pedaling where on the pedaling clock face this start of effective torque application
occurs is of minor importance, it is an instinctive action. Not so with the perfect pedaling technique in which precise timing and concentration is a vital factor in the simultaneous switchover of power application from one leg to the other.

 

[FrankDay]

Originally Posted by FrankDay
Pedal speed is the linear speed of the pedal and determines the necessary velocity of the muscle contraction before any force can be applied to the pedal.

You mean before any torque can be applied to the crank ?

Yes

In natural pedaling where on the pedaling clock face this start of effective torque application occurs is of minor importance, it is an instinctive action. Not so with the perfect pedaling technique in which precise timing and concentration is a vital factor in the simultaneous switchover of power application from one leg to the other.

Huh? It doesn't matter where one is in the pedaling circle, top, front, bottom, back, anywhere in between, the appropriate muscles must be contracting at the appropriate speed before a single in-ounce of forward torque can be applied to the crank arm. It doesn't matter what technique one is using.

 

[coapman]

YesHuh? It doesn't matter where one is in the pedaling circle, top, front, bottom, back, anywhere in between, the appropriate muscles must be contracting at the appropriate speed before a single in-ounce of forward torque can be applied to the crank arm. It doesn't matter what technique one is using.

That is true, but it's where in the pedaling circle one can start highly effective torque application that separates the value of different pedaling techniques on the ideal flat TT course. Where does your technique begin its highly effective torque application..