Pedal revs

[hubner]

...   Most keen cyclists pedal too fast when they have the option; it's what pro racing cyclists do, and it's good for your knees in the long run, but it's not the most biomechanically efficient.  75-80rpm gives more forward speed for less energy expended.

So pros pedal fast, say 90-100rpm, but they are using more energy than if they pedalled slower, like 75-80rpm, at the same speed?

[ACyclingRooster]

Hi hubner. If the pro's are pedalling  fast then the cadence is would be higher ( often seen with  Chris Froome ) and therefore less use of the same muscles that would be used in pedalling slower (higher gearing). I rode sprints and tubs permanently rather than the standard rubber of the day.
I had it albeit a long long time ago when I rode a 108" fixed gear Hetchins curly track frame (a 54/13),I could have used a 48/12 and got give or take the same gear inches but with a higher cadence.
I then would use a lower gear (52/18) during the Autumn/Winter period.

I rode with a few guys that would ride a very high cadence (twiddling) almost to the extent of bouncing on their saddles.

[ijsbrand]

The story always was that Lance Armstrong got into high rev cycling, because in a multi stage race it was profitable to save the legs and instead tax the respiratory system more, as that would recuperate a lot better from day to day.

Armstrong allegedly won a few Grand Tours, though it is difficult to find current information about that, so his riding style has been copied widely.

tl;dr pedalling in a high frequency has its virtues, but those may be different ones than normally thought.

[Samuel D]

If you look closely, you’ll see pros vary their cadence by more than the typical weekend warrior. When only low power is needed, they allow their cadence to drop right back, whereas many of them go over 120 RPM in short attacks.

Low cadence improves efficiency at low power, since less work is done spinning the legs against their internal friction. (At high power, efficiency takes a back seat to simple physiological possibility: you have to use a cadence that allows you to sustain the required power for the required duration. If that consumes more oxygen and energy, so be it.)

The need to vary cadence in this way seems obvious to me from my body’s feedback, but several of the guys I ride with are slaves to their cadence meter and spin at 90+ RPM while chatting on the way out of town at the start of a ride. Most of them don’t sustain that coming back into town when they’re knackered, but one does 100 RPM even then. I guess they’ve read an article or something. I prefer to listen to my body when it speaks clearly.

What was the question again?

[LittleWheelsandBig]

http://members.home.nl/vd.kraats/recumbent/pedal.html#Cadence%20and%20efficiency might be interesting reading for some.

[Brucey]

it is one of the oldest chesnuts in cycling, this. If you do enough miles then basically you can't afford to be pushing very hard on the pedals with every pedal stroke; the rate at which you are tearing down muscle fibres is likely to greatly exceed the rate at which they can be built up again. Pros (and other high milers) need to ride every day (even if it is not at any intensity) because unless they get plenty of blood flowing through their muscles for a few hours every day the ongoing repair processes don't work very well and you have rather  'dead legs' after a day off.  If you spend a month or two spending five to seven hours a day (average 100 miles plus) in the saddle, you will get some idea of what this feels like.

At high cadence there may or may not be internal friction but there are two major sources of inefficiency;
1) reciprocating losses; the weight of your legs flapping up and down is a lot of energy that is not perfectly conserved
2) co-ordination; unless you practice riding at high cadence then you won't be very good at it and you certainly won't be able to manage it in an efficient way when you are tired.

Pedalling in nice circles with some ankle action helps with both the above. It is a slightly old-fashioned obsession (one that French TV still panders to I think) but riders that are still pedalling  well in the latter stages of a race are often the ones to watch.

High cadence is a lot less easy to manage using longer cranks and this is (weakly) relative to leg length. So you won't find many shorter guys 'spinning' nicely on long cranks.

Power output can go up with cadence (for brief periods) until you run out of co-ordination, and it is possible to pedal effectively at much higher cadences than most folk think possible, IIRC when Ekimov set his track records his average cadence was over 140 or something.

Froome is a special case in that he uses oval chainrings; this will have an effect on the preferred cadence for any given rate of leg extension in the power stroke.  I'm sure that Sky have shown it works for them, but I can't help but feel that if they were truly wonderful, everyone in the peloton would be using them.

cheers

[rogerzilla]

I did some self-measuring on a turbo trainer years ago, and for 10-mile TT pace (maybe 300W in those days), 80rpm in a higher gear was a lot faster, for maximal aerobic effort, than 100rpm in a lower gear.

Looking at the charts seems to confirm this, unless you're a Cat 1 racer, when 100rpm is more efficient for your 400W output.  On a long ride at 200W, 60rpm is better.

[Samuel D]

At high cadence there may or may not be internal friction […]

There’s no maybe about it, at high cadence or otherwise! It may vary a lot from individual to individual, though, if nothing else because some riders have chunky legs with big joints and others are skinny and light-boned.

[…] but there are two major sources of inefficiency;
1) reciprocating losses; the weight of your legs flapping up and down is a lot of energy that is not perfectly conserved

I think this statement hinges on a strict definition of perfectly conserved. If there’s significant energy lost, where does it go? A spinning internal combustion engine does not lose energy to pistons and connecting rods flapping about because they’re balanced by their opposite numbers as legs on a bicycle seem to me to be too. (Of course there are minor frictional loses that go up with the weight of moving parts.)

I don’t see evidence on the road that pedalling nice circles has much to do with performance. You see pretty circles at the beginning of rides and clunky pedalling at the end and that to me suggests, if anything, that pretty circles are inefficient and can only be indulged in when fresh. Besides, those pistons in reciprocating engines don’t push circles and yet the entirety of the work they do is converted into crankshaft rotation.

Froome is a special case in that he uses oval chainrings; this will have an effect on the preferred cadence for any given rate of leg extension in the power stroke.

But their effect is to increase the gear ratio during the power phase of the stroke, so presumably with round chainrings Froome would spin even faster rather than slower.

I'm sure that Sky have shown it works for them, but I can't help but feel that if they were truly wonderful, everyone in the peloton would be using them.

Agreed, and the last Sky guy to win the Tour used round chainrings and a slow, grinding pedalling style even during attacks.

On a long ride at 200W, 60rpm is better.

And yet no-one does this, not even elite male pros for whom 200 W is a comfortable canter. Audax riders at half that power don’t either.

[LittleWheelsandBig]

My cadence on flat ground tends to drop to around 60 about 3 or 4 days into a long brevet. YMMV

A clubmate back in the day who was in the Aussie team time trial squad (100km, 4 men) found that they did their best performances at closer to 60 rpm than 90. Road racers need to use higher revs to attack and to respond to attacks.

[Samuel D]

Road racers need to use higher revs to attack and to respond to attacks.

This supposes they ride six-hour stages in a state of nervous tension about to attack or chase. I’ve watched enough racing to know that isn’t the case although of course road racing is a surge-y business. They choose their cadence for a balance of all performance factors as they understand and feel them.

Time trialists are phenomenally faddish in my limited experience. The specialists are also bulky because bulk is barely penalised, and so they can afford to ride lower cadences without recruiting many of their fast-twitch cells (not that the best ones have a lot of those anyway). And since there are no involuntary power surges, the optimum cadence can be lowered until the muscles are approaching fatigue-inducing forces without risk of going over that limit at the next corner.

Nonetheless, the best time trialists spin a lot faster than 60 RPM. All of the recent hour-record holders had fairly high cadences. The current holder, Wiggins, used over 100 RPM.

What do the 24-hour guys use?

[Brucey]

re reciprocating losses; the KE of the moving leg is converted to useful force in the cranks only if the mass of the legs is well coupled to the cranks. Because one's ankles are hinges, this coupling is not suitably rigid unless one's muscles are doing something. Unlike a nuts and bolts machine, a resisting force, even with no distance travelled,  is definitely 'work' for the human body to do.

Ankling is probably more efficient (if you can do it) in part because the speed of the the heavier parts of the leg is reduced and this means less resisting force is required. It also gives your other muscles a bit of a rest, so mixing it up like this during a ride is a handy thing to do.

Just pedalling better is useful; I quite often find when climbing that simply by concentrating on the quality of my pedal action, I can go a wee bit faster without an increase in pulse rate.

cheers

[LittleWheelsandBig]

I've ridden enough high level road races to know that road racers train for higher cadences than pure time trialists use because road racers need to be able to turn the pedals over quickly during attacks to get on the wheel or make a gap. That means their 'relaxed cadence' is also higher. Trackies need a high cadence because they have to start their event from a dead stop and can't change gear. That said, I've never ridden longer than a week-long amateur stage race (3rd overall, thanks for asking).

Regarding the relative advantages of high and low cadence for road racing, Hinault, Lemond and Ullrich (all noted TTers) seemed to do quite well despite low cadences, particularly when climbing.

[rogerzilla]

The human body is about as efficient as a petrol engine, so developing 300W in a TT takes about 1200W of energy and generates almost 1kW of waste heat, which will be obvious to anyone who's sweated their guts out on a turbo trainer.  Efficiency is improved by training to some extent.

It's been said, fairly accurately, that your most efficient pedalling technique is the one you adopt at the end of a long ride to exhaustion - pretty much LWaB's experience.  There are reasons to pedal faster and use lower gears ( I do it because of dicky knees years ago - it's no longer necessary but became a habit) but if you just want maximum speed or distance for minimum energy input, it's not the way.

[Ian H]

It's been said, fairly accurately, that your most efficient pedalling technique is the one you adopt at the end of a long ride to exhaustion - pretty much LWaB's experience.

I don't think he quite said that.
My pedalling can become sub-optimal when I'm very tired, but, as with Brucey's experience, if I concentrate and pedal efficiently, I get more speed for the same effort.  There does seem to be a mental tiredness that makes sustaining that difficult, although it's pretty much automatic with fresh legs and brain.

As for cadence, mine varies considerably, even when I'm not on fixed.

[mzjo]

At high cadence there may or may not be internal friction […]

There’s no maybe about it, at high cadence or otherwise! It may vary a lot from individual to individual, though, if nothing else because some riders have chunky legs with big joints and others are skinny and light-boned.

[…] but there are two major sources of inefficiency;
1) reciprocating losses; the weight of your legs flapping up and down is a lot of energy that is not perfectly conserved

I think this statement hinges on a strict definition of perfectly conserved. If there’s significant energy lost, where does it go? A spinning internal combustion engine does not lose energy to pistons and connecting rods flapping about because they’re balanced by their opposite numbers as legs on a bicycle seem to me to be too. (Of course there are minor frictional loses that go up with the weight of moving parts.)

I don’t see evidence on the road that pedalling nice circles has much to do with performance. You see pretty circles at the beginning of rides and clunky pedalling at the end and that to me suggests, if anything, that pretty circles are inefficient and can only be indulged in when fresh. Besides, those pistons in reciprocating engines don’t push circles and yet the entirety of the work they do is converted into crankshaft rotation.

Froome is a special case in that he uses oval chainrings; this will have an effect on the preferred cadence for any given rate of leg extension in the power stroke.

But their effect is to increase the gear ratio during the power phase of the stroke, so presumably with round chainrings Froome would spin even faster rather than slower.

I'm sure that Sky have shown it works for them, but I can't help but feel that if they were truly wonderful, everyone in the peloton would be using them.

Agreed, and the last Sky guy to win the Tour used round chainrings and a slow, grinding pedalling style even during attacks.

On a long ride at 200W, 60rpm is better.

And yet no-one does this, not even elite male pros for whom 200 W is a comfortable canter. Audax riders at half that power don’t either.

1. There are big losses possible within the human body cycling. If you don't have the same power output from each leg on up and down strokes you have to waste the energy of one leg pushing the other one back up. (That of course is what training is all about, provided you are serious about balancing both legs.) Wait until you have an artificial joint or two and a bit of arthritis and you 'll understand. My cadence has gone down dramatically in the last 5 years because of this but even slight imbalances would have a noticeable effect, particularly when you're tired.

2. IC motors are not perfectly balanced, although the imbalances reduce with an increasing number of cylinders. The energy gets dissipated as heat, just like in human beings. Try running your car without coolant in the canicule if you don't believe me - and try riding in the same canicule without adequate cooling as well. You may have to cool off in a mountain stream!!

3. The actual effect of an oval ring - increasing or decreasing the lever and the resulting cadence - depends on the orientation of the ring. Biopace rings for example have an orientation which reduces the perceived gear and increases cadence on the down stroke. Sheldon Brown does have something to say on the matter (personally having used a Biopace ring as a granny ring I found the reduction in effort on the power stroke really useful climbing at slow revs and "high" effort and the uneven cadence completely deranging when the effort reduced at the end of a climb and the cadence went up). I don't know how Froome has his rings fitted. It is probably all documented somewhere but it doesn't much interest me! 

[zigzag]

i always ride by feel, shorter intense rides tend to average around 90rpm, audaxes 70-80rpm, very long rides under 70 (lots of out of saddle riding/climbing). i start to feel discomfort and inefficiency above 105ish rpm.

[LittleWheelsandBig]

It's been said, fairly accurately, that your most efficient pedalling technique is the one you adopt at the end of a long ride to exhaustion - pretty much LWaB's experience.

I don't think he quite said that.
My pedalling can become sub-optimal when I'm very tired, but, as with Brucey's experience, if I concentrate and pedal efficiently, I get more speed for the same effort.  There does seem to be a mental tiredness that makes sustaining that difficult, although it's pretty much automatic with fresh legs and brain.

As for cadence, mine varies considerably, even when I'm not on fixed.

Mostly, towards the second half of a long brevet, I don't find that pedalling faster is more efficient (for me, YMMV) during low intensity riding. It often feels more comfortable (legs, saddle, back and shoulders) to pedal slower for the same road speed. It certainly seems easier to chat at lower revs for the same speed. If I need or want to ride faster, then my cadence tends to increase 'a bit'. That seems to follow the 'higher cadence for high power, lower cadence for low power' approach. My ageing knees can complain if I try to put out high power for long periods at low revs.

[LittleWheelsandBig]

What do the 24-hour guys use?

Broadwith (Wheels of Fire OTP) used 55/39 and 11/28 for his recent LEJOG record. http://www.veloveritas.co.uk/2018/06/30/michael-broadwith-jun18/

[DuncanM]

Froome is an odd hybrid of cadences. He climbs at a very high cadence, but TTs at a noticeably lower one. I think that Brucey is correct in that lower cadences allow for better power but at the cost of more muscle damage/tiredness. Most Grand Tour TTs are relatively short and only one effort in the day so you can afford to damage your legs a bit on TT day, whereas there is usually more than 1 climb in a day and therefore it's important to let the CV system take the strain. Also, it's easier to be explosive and attack/defend from a higher cadence, and that's useful in the mountains but not in a TT.