Increasing Cadence

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lukesdad

Guest
GrasB said:
In simplistic terms: power = torque * rpm
So if the the bike is giving resistance for 225w & the rpm drops you're simply applying more torque to the pedals.
Applying more force to the pedals. You can only increase torque by lengthening the cranks.
 

jimboalee

New Member
Location
Solihull
lukesdad said:
Applying more force to the pedals. You can only increase torque by lengthening the cranks.

This is indeed correct, but give the man some poetic licence.

When an engine is on the dyno, we don't say "apply more piston force on the crankshaft, old bean", we say "give it more torque , ya bastard".:smile:
 

GrasB

Veteran
Location
Nr Cambridge
marzjennings, please note I used the word for rather than is. Those words aren't interchangeable without changing the meaning of the sentence.

If the setting is that the bike will 'eat' 225w then it will. Now it's up to you how you output that 225w, you can do it at high rpm & low torque, low rpm & high torque. As the bike knows the rpm it can work out what resistance to load the pedals with so that it will 'eat' 225w of power.
 

GrasB

Veteran
Location
Nr Cambridge
jimboalee said:
On something more expensive than a gym bike, an engine test dynamometer for instance, I can set the controller to absorb 25 kW no matter what the engine rpm. If I open the throttle, the engine will rev away and the dyno' will apply load to stay at 25kW.
I find it's more useful setting it to 'absorb' say -50kW....
 

lukesdad

Guest
sarahpink said:
ive seen spinning classes advertised, does anyone feel their worth a short to improve your cadence?
They will improve your fitness, but you would have to do specific cadence training over some considerable time for them to be of benefit in cadence technique IMO.
 

jimboalee

New Member
Location
Solihull
The definition of "Fitness" is the ability of the body's systems to transport oxygen and fuel to the working muscles at a rate which will allow sustained activity.

If you are a spinner or a grinder, the oxygen and fuel must get to the muscles to allow you to keep the power output.

Pedalling slowly on a gym bike at 40 rpm with the Watts setting at 360 will cause Hypertrophy, and as a result, improve fitness.

Any cycling coach worth his salt will instruct a rider to train at EVERY condition that might happen.
That is:- Spinning away at 120 rpm producing 450 Watts so the rider can get across the finish line before anyone else AND standing up pedalling at 40 rpm producing 450 Watts for when the short 18% hills appear.

No rider likes to be overtaken in the final 50m, nor does he like having to get off and walk his bike up a short steep hill.

[Don't take these values as true life examples, they are straight off the top of my head. But I hope you understand the principle]
 

lukesdad

Guest
Agreed. Training at extremes in all forms will improve your performance. i was only trying to illustrate to Sarah what the benefits of a spinning class maybe to her,using my poetic license :blush: . Of course on its own it may not be of use at all but with other training it may well be, as long as an overall plan is constructed.

As to increasing cadence to an rpm that you can be comfortable with, unfortunately, there is no quick fix that I know of.
 

jimboalee

New Member
Location
Solihull
I may be a lumbering grinder these days, turning the cranks at 50 – 80 rpm in 'normal' riding.

Back when I was a fitter, younger competitive rider, my bike had a 108" top ( 52 x 13 ). If I wanted to rattle along at over 30 mph with the group on shallow downhills, I HAD to pedal fast.
The bike had a 45" lowest, so low rev mashing uphill was another 'HAD to'.

Nowadays, roadrace bikes have gearing from thirtysomething all the way up to 130". It is not very often a rider 'spins' at 100 rpm in 130".

I say, learn how to use ALL the rev range.
 

Fiona N

Veteran
My goodness, there's some wool-pulling going on here :biggrin:

All these arguments about power, HR and cadence are missing the essential physiological understanding of how a human body works.

Consider moving a load at slow speed - analogous to low cadence. For a given output (power, if you like), the main force-producing muscles are dominant in both result and energy use over the muscles which control the stability of the working limb(s). For a cyclist, this means that, until you get to 'hauling on the handlebar' levels of leverage, lower cadences require a smaller proportion of input from stabilising muscles. With increasing cadence, for the same output, the effort required from the main propulsion muscles is smaller but the stabilising muscles are increasingly required to off set the tendency of the limbs to lose alignment, hips to sway, shoulders to rock etc. At very high cadences with low resistance - typical for spinning class intervals - the stabilising muscles are the major energy-consuming part of the system since the effort required from the propulsion muscles is vastly reduced.

Since the measured (power) output is the same for the different cadences in your example, you've been making the assumption that the body is making the same exertion to achieve it - clearly this isn't the case, as Jimbo's initial experiment shows.

Training is used to improve the efficiency of the stabilising muscles (also called postural system as it's basically responsible for keeping us upright) - typically they're weak relative to propulsion muscles. People who are more anatomically 'perfect' (better joint alignment, less stiff hamstrings and other muscles etc.) will usually find high cadences easier than those who have muscular and joint imbalances as the demands on the postural system are smaller.

This explains why HR isn't simply correlated with power output (so a set of valid ramp tests for comparison over a training period requires a test protocol so that power output is achieved using the same gearing/cadence in each test), nor calorie expenditure with power, as you're missing a component which is variable with cadence.


BTW The importance of the postural system in sports has only been recognised in the last 20 years or so as intense training to develop propulsion muscles can lead to parts of the postural system being rendered 'redundant' - which leads to instabilities developing. Shoulder injuries in swimmers were a good example as the over development of the big muscles like traps/pecs for propulsion lead to the smaller muscles, which control shoulder alignment through the complex 3-D movements, becoming ineffective. The exercises required to correct this are small precise movements (think Pilates) to target the individual postural muscles and strengthen them. Often cyclists' knee problems are of a similar origin with marked but unbalanced development of the quads.


Lecture over :tongue:
 

jimboalee

New Member
Location
Solihull
Fiona N said:
My goodness, there's some wool-pulling going on here :biggrin:

All these arguments about power, HR and cadence are missing the essential physiological understanding of how a human body works.

Consider moving a load at slow speed - analogous to low cadence. For a given output (power, if you like), the main force-producing muscles are dominant in both result and energy use over the muscles which control the stability of the working limb(s). For a cyclist, this means that, until you get to 'hauling on the handlebar' levels of leverage, lower cadences require a smaller proportion of input from stabilising muscles. With increasing cadence, for the same output, the effort required from the main propulsion muscles is smaller but the stabilising muscles are increasingly required to off set the tendency of the limbs to lose alignment, hips to sway, shoulders to rock etc. At very high cadences with low resistance - typical for spinning class intervals - the stabilising muscles are the major energy-consuming part of the system since the effort required from the propulsion muscles is vastly reduced.

Since the measured (power) output is the same for the different cadences in your example, you've been making the assumption that the body is making the same exertion to achieve it - clearly this isn't the case, as Jimbo's initial experiment shows.

Training is used to improve the efficiency of the stabilising muscles (also called postural system as it's basically responsible for keeping us upright) - typically they're weak relative to propulsion muscles. People who are more anatomically 'perfect' (better joint alignment, less stiff hamstrings and other muscles etc.) will usually find high cadences easier than those who have muscular and joint imbalances as the demands on the postural system are smaller.

This explains why HR isn't simply correlated with power output (so a set of valid ramp tests for comparison over a training period requires a test protocol so that power output is achieved using the same gearing/cadence in each test), nor calorie expenditure with power, as you're missing a component which is variable with cadence.


BTW The importance of the postural system in sports has only been recognised in the last 20 years or so as intense training to develop propulsion muscles can lead to parts of the postural system being rendered 'redundant' - which leads to instabilities developing. Shoulder injuries in swimmers were a good example as the over development of the big muscles like traps/pecs for propulsion lead to the smaller muscles, which control shoulder alignment through the complex 3-D movements, becoming ineffective. The exercises required to correct this are small precise movements (think Pilates) to target the individual postural muscles and strengthen them. Often cyclists' knee problems are of a similar origin with marked but unbalanced development of the quads.


Lecture over :tongue:

Fantastic.

I would have said, correct me if I'm in error, that in addition, the brain is bringing the Antagonistic muscle into operation due to the 'over fast, extraordinary' movement of the Agonist muscle.
I would say that if this is the case, the high speed movement is not suited to that individual.

More energy is required ( which results in higher HR ) and therefore wasted.

OR, if the individual is on a fat loss regime, beneficial. If the individual is participating in an endurance event, disadvantageous.
 

lukesdad

Guest
Very informative Fiona,and explains a lot of the exercises we were made to do as youngsters when I used to swim competively,never did understand them and it was alot more than twenty years ago more like 35 our coach must of either been very enlightened or very lucky but I think he was avery good coach Peter Harding ever heard of him?

To get back to the original topic, a rider with heavier legs I.e large propulsion muscles will find it harder to "spin" due to the effort required to move the larger mass at higher speeds. To a lesser extent crank length as well as length of leg will have a bearing as well this, is where torque does come into play. Angle that force is applied will also have a small effect on torque.

This is not contradicting anything you have said,more just following on.

Just one word on ramp tests, not everybody can access one easily,hence my development of my own tests,which we have crossed swords on previously.
 

marzjennings

Legendary Member
jimboalee said:
A gym bike is just the same as a Cyclops Powerbeam Pro trainer.

It has a load cell which senses Torque and a rev counter that counts the revs.

kW = ( Torque [Nm] x rpm ) / 9549.3


Cadence is NOT directly related to HR. HR is a consequence of moving your legs more times per unit time.

When we say 'directly related', it means there is a solid, undisputed correlation factor to convert from one unit to the other.

eg. kCals/min = kW x 14.3197

If my HR is 160 and my cadence is 80, the correlation factor would be HR = cadence x 2.0000

When my cadence is 90, is my HR 180? No. it's not related.

Nor is HR and kCals/min.

As seen by my own eyes, when the absorption of the gym bike was 225, my HR was 153 OR 144, dependent on cadence ( the number of times my legs are moving up and down ).

I have mentioned on this chatboard before about performing a 'Natural cadence' test.
It involves setting the gym bike to a nominal absorption and then pedalling, increasing the cadence very slowly through a wide rev range.
When your HR is lowest, that is your 'Natural cadence' and the revs which make your heart beat less for the power output. Well, to be truthful, it's the rate of effort that your muscle fibre Fast/Slow twitch balance is most comfortable with.

Believe it or not, mine is 45 rpm. That is why I'm able to climb a 20% hill on a 32" gear at 3 mph at 33 rpm.

You can define 'directly' as you like, but as a Cornishman I choose to abuse the word 'directly' as required. But semantics aside we agree then that cadence and HR are related and as Fiona mentioned in part due to increased effort required to keep the maintain a smooth and effective pedaling action. You only have to look at track cyclists, who require greater upper body strength to be able to smoothly pedal at +180rpm, to understand the increased effort to pedal and maintain a high cadence. Also why it's a lot easier to hit a higher cadence on a gym bike or trainer, which is being held and supported, than a bike out on the open road.

But would you say that someone's 'Natural cadence' is more a reflection of their current state of fitness and strength rather than their basic untrained physiology?


edit...just found this link if folks want a read...

http://www.fims.org/default.asp?pageID=213202031
 

jimboalee

New Member
Location
Solihull
I'm going to try 180 rpm on my slicked up MTB tonight.

36" gear at 19.5 mph. Api Sapis, I expect.

I usually ride that speed on 78" at 83 rpm.

What would happen to my HR if I tried 180 rpm on the 78" gear?

42 mph.....

You're guess is as good as mine, because HR is not related to any other metric.

What you are getting confused with is 'HR and exertion follow a trend'.

HR increases as exertion increases. If you try to put numbers and equations on it, you will have to recalculate the curve fit coefficients after you have improved your fitness just a little.
Maybe on a weekly basis.

Then YOU will have a frig factor for YOU, for that moment in time. Your frig factor will change after your next training session.
 
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