so what about cadence

[FrankDay]

Where does that leave your shorter cranks ?

In pretty good shape actually. For any given cadence the loss per revolution will be less with shorter cranks because pedal speed is less. So, at a cadence of 90 the losses will be substantially less with 145 cranks than 175 cranks. Or, we can ride the shorter cranks at a higher cadence without exceeding the longer cranks loss (up to a point, of course). This can help explain why there is a wide range in crank length where power remains pretty constant.

 

[JayKosta]

Frank, an interesting research study would be to:
1) actually measure the the 'Zero Torque metabolic cost' (e.g. O2 usage) at several specific 'free spin' (extremely low torque) cadence rates (60/ 70/ 80/ 90/ 100/ 110).
2) measure a form of 'pedaling efficiency' (Power / O2 usage) using a fixed Power value (e.g. 125W) at the same cadence points.
3) repeat #2, but instead of a fixed Power amount, attemp to produce maximum sustainable Power.

The theory to be tested is whether the 3 measurements when charted in line graph format would produce 'cross over' points similar to an economics chart of Cost vs. Demand.

Jay Kosta
Endwell NY USA

 

[FrankDay]

Frank, an interesting research study would be to:
1) actually measure the the 'Zero Torque metabolic cost' (e.g. O2 usage) at several specific 'free spin' (extremely low torque) cadence rates (60/ 70/ 80/ 90/ 100/ 110).
2) measure a form of 'pedaling efficiency' (Power / O2 usage) using a fixed Power value (e.g. 125W) at the same cadence points.
3) repeat #2, but instead of a fixed Power amount, attemp to produce maximum sustainable Power.

The theory to be tested is whether the 3 measurements when charted in line graph format would produce 'cross over' points similar to an economics chart of Cost vs. Demand.

Jay Kosta
Endwell NY USA

You could run that test yourself using HR as your oxygen cost proxie (they track very well but you wouldn't get a true oxygen cost number but the numbers should be correct relatively)

My calculations suggest the oxygen cost of cadence varies with the cube of the cadence. It could also be done with crank length where my calculations suggest at the same cadence that oxygen cost varies with the square of the crank length.

Anyhow, it would be interesting to see if such data could give the rider information as to where "optimum" is for them at any given power.

 

[FrankDay]

Here is a study that goes to the question as to why power drops beyond optimum cadence.

http://www.ncbi.nlm.nih.gov/pubmed/17414806

CONCLUSION:

During nonisokinetic sprint cycling, the decrease in power output when pedaling rates increased beyond PRopt may be partly explained by suboptimal muscle coordination.

WHAT!!! Pedaling coordination matters? who'd a thunk it?

 

[elapid]

Here is a study that goes to the question as to why power drops beyond optimum cadence.

http://www.ncbi.nlm.nih.gov/pubmed/17414806
WHAT!!! Pedaling coordination matters? who'd a thunk it?

Muscle coordination, not pedalling coordination. There's a difference.

 

[JayKosta]

Here is a study that goes to the question as to why power drops beyond optimum cadence.

http://www.ncbi.nlm.nih.gov/pubmed/17414806
...

-----------------------------------
The study is about sitiuations of 'max effort sprinting' -
"8-s nonisokinetic sprints" (meaning that the resistance was kept constant and the RPMs were allowed to increase).

From the abstract, it isn't clear whether Power Output really dropped during the tests - it probably didn't. The Power increased, assuming the RPMs increased (as would be expected during a sprint)!

The study seems to show that as someone pedals very fast and hard, their muscle coordination decreases which reduces the EFFICIENCY of their power production, but still results in more Power and accelerating RPMs.

The reduction in efficiency at high RPM could certainly explain why long-term power output would be less.

Perhaps the best sprinters are 'neurologically gifted' and are able to maintain good muscle coordination even at high RPM and power.

Jay Kosta
Endwell NY USA

 

[FrankDay]

-----------------------------------
The study is about sitiuations of 'max effort sprinting' -
"8-s nonisokinetic sprints" (meaning that the resistance was kept constant and the RPMs were allowed to increase).

From the abstract, it isn't clear whether Power Output really dropped during the tests - it probably didn't. The Power increased, assuming the RPMs increased (as would be expected during a sprint)!

The study seems to show that as someone pedals very fast and hard, their muscle coordination decreases which reduces the EFFICIENCY of their power production, but still results in more Power and accelerating RPMs.

The reduction in efficiency at high RPM could certainly explain why long-term power output would be less.

Perhaps the best sprinters are 'neurologically gifted' and are able to maintain good muscle coordination even at high RPM and power.

Jay Kosta
Endwell NY USA

Very high power requires high rpm because, if we didn't increase the rpm, we would be forced to increase the pedal forces beyond our ability. It seems to me that the optimum increase in rpm would be that which balances the pedal speed increase with the pedal force increase that allows the muscles to do the most work.

I found this interesting because it gives a third reason to explain why efficiency would drop at high rpm. I always thought it had to do with increasing losses just from the pedaling motion (increasing with the cube of the cadence) and reduced muscle contractile efficiency (from contractile speed being above optimum). Now we can add it affects pedaling (or muscle, what is the difference?) coordination to reduce pedaling efficiency.

It seems to me that what this should say to us is that riding at high rpm for the sake of being at a high rpm reduces efficiency beyond what can be done using a lower, more optimal, rpm. I look forward to hearing the argument as to how reducing efficiency is a good thing. Edit: It may be a necessary thing, such as when riding at the highest power for sprinting, but reducing efficiency serves no purpose in and of itself.

 

[coapman]

Here is a study that goes to the question as to why power drops beyond optimum cadence.

http://www.ncbi.nlm.nih.gov/pubmed/17414806
WHAT!!! Pedaling coordination matters? who'd a thunk it?

That only happens in natural pedaling styles because of the dead spot sector and the biological delay. It does not occur with the perfect pedaling technique because the muscles are already getting the signal from the brain during the upstroke to be prepared for instant maximal power application. That requires total concentration on the clear objectives to be followed, unlike natural unconscious pedaling styles.

 

[FrankDay]

I just ran across this interesting study. The effect of pedaling rate on coordination in cycling.. It is commonly believed that higher cadences reduce muscle fatigue because they reduce force on the pedal for the same power. But, here is a study that looks at muscle activation for the same power (250W) in competitive cyclists at different cadences. Low and behold, in general, the highest activations occurred at the highest cadences (when the pedal forces would be the least) with the minimum activations occurring in the 75-90 cadence range (check out table 3). Some muscle activations were quite high in the "pushing muscles" at the very low cadence but not a lot higher than seen at the highest cadences. If you believe pedaling (making the pedals go around), per se, doesn't require any energy, how do you explain this finding?

Here are a couple of images from that paper.

 

[coapman]

I just ran across this interesting study. The effect of pedaling rate on coordination in cycling.. It is commonly believed that higher cadences reduce muscle fatigue because they reduce force on the pedal for the same power. But, here is a study that looks at muscle activation for the same power (250W) in competitive cyclists at different cadences. Low and behold, in general, the highest activations occurred at the highest cadences (when the pedal forces would be the least) with the minimum activations occurring in the 75-90 cadence range (check out table 3). Some muscle activations were quite high in the "pushing muscles" at the very low cadence but not a lot higher than seen at the highest cadences. If you believe pedaling (making the pedals go around), per se, doesn't require any energy, how do you explain this finding?

Here are a couple of images from that paper.

Are you for or against using higher cadence and could you explain why you believe your way or idea is best.

 

[FrankDay]

Are you for or against using higher cadence and could you explain why you believe your way or idea is best.

I am for using the cadence that optimizes efficiency for the power one is generating.

 

[coapman]

I am for using the cadence that optimizes efficiency for the power one is generating.

Ok. What would you use in the individual track pursuit ?

 

[FrankDay]

Ok. What would you use in the individual track pursuit ?

That would depend on the length of the race and the ability of the athlete. Track pursuit involves the need to both accelerate quickly and sustain a top end speed, two goals that work against each other when choosing gearing, to minimize the time to get from point a to point b. For shorter races acceleration is relatively more important. For longer races sustained top speed is relatively more important. Each athlete needs to experiment to see what the best combination of gearing/crank length is for them for the race they are doing.

 

[coapman]

That would depend on the length of the race and the ability of the athlete. Track pursuit involves the need to both accelerate quickly and sustain a top end speed, two goals that work against each other when choosing gearing, to minimize the time to get from point a to point b. For shorter races acceleration is relatively more important. For longer races sustained top speed is relatively more important. Each athlete needs to experiment to see what the best combination of gearing/crank length is for them for the race they are doing.

The question was, what would you yourself use in a (let's say 4K) pursuit. What would you use in a flat non technical 25 M road TT.

 

[FrankDay]

The question was, what would you yourself use in a (let's say 4K) pursuit. What would you use in a flat non technical 25 M road TT.

I have no clue what I myself would use in a pursuit as I have no personal experience with track racing. Regarding a 25M road TT I would probably ride 125-130 mm crank length at a cadence of about 80, and averaging about 230-50 watts. If I were forced to ride 170mm cranks I would probably ride at a cadence of 60 or so.

 

[FrankDay]

I have no clue what I myself would use in a pursuit as I have no personal experience with track racing. Regarding a 25M road TT I would probably ride 125-130 mm crank length at a cadence of about 80, and averaging about 230-50 watts. If I were forced to ride 170mm cranks I would probably ride at a cadence of 60 or so.

BTW, I think the above post should reinforce my belief that cadence (as most people think of it) is a red herring and that what is really important is pedal speed.

 

[Dear Wiggo]

I have no clue what I myself would use in a pursuit as I have no personal experience with track racing. Regarding a 25M road TT I would probably ride 125-130 mm crank length at a cadence of about 80, and averaging about 230-50 watts. If I were forced to ride 170mm cranks I would probably ride at a cadence of 60 or so.

Your lack of track experience is telling.

Can you estimate a 3km pursuit time based on your road TT experience (add 20% to your 20km TT speed), back calculate your gear size for the 60rpm cadence and then work out the torque required to get that gear up to speed from a standing start with a proper stiff track bike setup of 9kg + your own body weight?

Something tells me you won't even move off the start line.

 

[coapman]

BTW, I think the above post should reinforce my belief that cadence (as most people think of it) is a red herring and that what is really important is pedal speed.

In both cases can you explain why.

 

[FrankDay]

In both cases can you explain why.

This is from a Martin slide presentation

• Power Output and Pedal Speed account for 98% of the varaibility in metabolic cost in this group of 9 cyclists.
• 99% of the variablity for each individual
• Of the remaining 2% variability, crank length and pedaling rate each accounted for 1% or 0.02% of tota

Is this good enough for you? After power pedal speed is king regarding metabolic cost.

 

[coapman]

This is from a Martin slide presentationIs this good enough for you? After power pedal speed is king regarding metabolic cost.

No, when a rider sets off on his bike, how does he control his pedal speed?

 

[veganrob]

This is from a Martin slide presentationIs this good enough for you? After power pedal speed is king regarding metabolic cost.

Would you please explain the differences between Pedal speed, cadence and pedaling rate. I am not understanding the differences clearly. Thank you.

 

[coapman]

Would you please explain the differences between Pedal speed, cadence and pedaling rate. I am not understanding the differences clearly. Thank you.

I understand pedaling rate to be cadence and pedal speed to be calculated from cadence and crank length but what I don't understand is, if pedal speed is calculated in that way how can cadence and crank length be dismissed as unimportant.

 

[JayKosta]

I understand pedaling rate to be cadence and pedal speed to be calculated from cadence and crank length but what I don't understand is, if pedal speed is calculated in that way how can cadence and crank length be dismissed as unimportant.

-------------------------------------
It is not that cadence and crank length are UNIMPORTANT (your words).
But the statistical examination of the various factors indicates that POWER and PEDAL SPEED are what SHOWS THE HIGHEST CORRELATION to variations in metabolic cost.

In techincal reports, the authors (usually) choose their words very carefully and try to make their statements very precise with that set of words. They are NOT saying anything more or less than than what appears in print.

Jay Kosta
Endwell NY USA

 

[42x16ss]

No, when a rider sets off on his bike, how does he control his pedal speed?

Through cadence and gear selection. Come on, is it really that hard a concept?

 

[FrankDay]

Would you please explain the differences between Pedal speed, cadence and pedaling rate. I am not understanding the differences clearly. Thank you.

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.