When you see the word “POWER” used in cycling, what does it mean to you?

[RPS]

The technical definition can be simple and straight forward, but many of us keep using the word as if it has many meanings – which is OK as long as we are speaking the same lingo.

So what does “POWER” mean to you? Do you think in terms of watts, big muscular legs, fast speed, or what? Please take it in any courteous direction.

Thanks,
Rick

[hansolo758]

I think in terms of watts. I don't think in terms of muscle mass. I presume climbers in the TdF, who are generally little skinny guys, produce lots of power. Nor do I think of speed -- again, watts produced going uphill don't necessarily result in speed. I'll concede that sprinters also produce lots of power and are generally muscular guys. I'll also concede the point that just producing watts doesn't count for squat unless you're doing something with it -- like going uphill or sprinting like crazy.

[Ti Designs]

There are two cases I can think of, which mean very different things:

Case 1: Power numbers used to indicate change in output over time for an individual - a useful measurement for tracking progress.

Case 2: Pointless numbers spewed by bike nerds to compare their fitness.

[Blue Jays]

Imagery is typically very high-speed sprinting propelled by 24.00" leg cannons.

[gemship]

extreme power Colnago

[fiamme red]

http://www.bikecult.com/works/archive/04bicycles/dpowerTKCfr.JPG

[93legendti]

Lemond, Hinault, Lance or Mig Indurain riding away from the group on a mountain.


Mancebo makes me realize that cycling is not just about power.

[bzbvh5]

I think of it as: the more power you average, the smaller sprocket you can ride in while keeping a good cadence. Thus, the faster your average MPH or KMPH (for you non Americans) will be.

My likeness, Magnus Backstead who won the flat Paris to Roubaix race a couple of years ago, can produce a lot of watts but weighs too much to take advantage of his power over mountain tops. So there might be an average watts to weight ratio for ultimate performance depending on the type of race. Which also begs the question: "Is watts produced a function of the weight of the rider pushing on the pedals"?

[zap]

I don't have enough.

[EDS]

I don't have enough.

+1

[DarkStar]

Power!

[shiftyfixedgear]

The scientifical definition of Power is how fast n' hard you can stomp in order to make the roundy-roundy spin fasta.

Kind of more like the Mash Potatoes than the Slop. If the Frug is in there . . . well - yer doin' it all wrong.

[Dave]

As an engineer I always keep in mind that power = torque X cadence and each is of equal importance. If you can't climb at 75-90 rpm, you'll need to put out a lot of torque to make much power. When climbing, power/weight is most important.

If you ride on flatter terrain, then weight is less critical and it's power to frontal area that is more important. Lightweights like me usually have a poor ratio and a harder time on the flats. That's when you tuck in behind some big guy.

Using a powertap wheel for a few months has been enlightening.

[jimp1234]

Me neither. And if you've done any kind of training with a power meter, then compare what you're generating and for how long with the wattage generated by the pros who do 400+ watts avg. for an hour or two on some of the big tour climbs, you really understand that those guys are on a different planet compared to us average joes or "freds".


I don't have enough.

[johnnymossville]

I think of Zabel, Boonen, Cavendish. Sprinters.

[Karin Kirk]

It reminds me of a day of skiing with Dave and a Serotta employee who was snowboarding. The Serotta employee (sadly I can't remember who) got stuck in a flat spot and I offered him my ski pole so I could tow him along by skating. Once I started pulling he exclaimed: "I can feel the power!"

It seemed very funny at the time.

That has become our standard household reference to something powerful. :D

[Peter P.]

In Thomas Chapple's Book, Base Building For Cyclists, he defines power as "the ability to apply maximum force quickly", like beginning a sprint.

While I disagree, I could accept his interpretation.

I view power as the ability to apply a lot of force into the pedals at racing cadences for longer periods of time such as time trialing. You know; that big gear thang.

I could see how you could lump Chapple's definition with mine.

I often confuse power with speed. I view speed as a high top end for sprints or initiating/closing breaks, but for some reason I only think of it in conjunction with a high cadence though I can't say why.

[Louis]

If it's used in a marketing context it makes me think of HYPE.

[RPS]

In Thomas Chapple's Book, Base Building For Cyclists, he defines power as "the ability to apply maximum force quickly", like beginning a sprint.

While I disagree, I could accept his interpretation.
.......snipped........You are smart to disagree. While that ability may have great value, it's not power.

[Viper]

I think of Zabel, Boonen, Cavendish. Sprinters.

I think of the climbers. :) Man, I know watts are getting light up like the 4th of July down the line in a sprint, but the first week of le Tour, for me, is so boring. For me, pain is the real power and nothing creates more pain like the mountains.

When I think of power in cycling, the vision that comes to mind is having the ability to generate power, standing up and breaking away on a serious incline while everyone else is powerless.

[RPS]

In more technical terms, we can say that “power” is the “rate” at which “work” is done, or energy is transmitted. Hence,

Power = Work / Time

Please note that work is not the same thing as a force. Many throw the word “force” around quite often as if it creates work and hence power, but that’s not “necessarily” the case. For instance, when I stand still, my feet apply a force of about 75 pounds each on the concrete floor but that results in zero work being done; and therefore zero power generation.

For a force to do work it has to have movement in the direction it is being applied. In the case of cycling, when we coast we may apply a downward force to the pedal while at the bottom of the stroke, but that force does zero work, and therefore generates no power.

To make sense of power generation, one must always distinguish between forces and work. They are not interchangeable – it’s an important distinction that can’t be overlooked.

[Tom Kellogg]

That is what horsepower and watts are. The SRM, PowerTap, etc systems measure it. "Strength" is just a measurement of force, not over time. So when I think of power related to cycling, I am thinking in watts. If you are willing to go through the pain and frustration (and expense) of training "with power," you will end up more powerful. Call a good coach. They can help.

[geoffm]

...that would be watts (threshold) per kilogram of body weight to me.

[RPS]

FOOD FOR THOUGHT

Since the effect of pedaling smoothness is what led to this thread, I’d like to use an extreme yet easy to visualize non-cycling example of non-uniform power delivery to question the technical importance of smoothness and the influence it may have on the ultimate goal (i.e. – to generate enough power to accomplish an intended task).

The least smooth (roughest) power generating item I use on a regular basis is my 5-HP single-cylinder 4-stroke lawn mower. What makes it rough is that it fires only once every two revolutions, hence once every 720 degrees of rotation (by comparison even poor cyclist “fire” once every 180 degrees making their power delivery far smoother). The engine’s power stroke is limited to no more than 180 degrees of rotation, right? Therefore, actual power is generated no more than ¼ of the time; the other ¾ plus of the time there is actually “negative” power being generated (due to friction). When averaged, however, it all works out to 5-HP. That means that during the ½ revolution of the power stroke the instantaneous power generation exceeds 20-HP, but when averaged over two revolutions it comes out to 5-HP. Does anyone really care that most of the time nothing productive is taking place?

My question is this: Because power is generated intermittently only ¼ of the time or less, does it mean that only ¼ of the grass I run over gets cut? Of course not. We know that the average is what counts because there is enough energy stored in the flywheel effect of the engine and blade to keep the mower running “well enough” to do its intended job during the other ¾ of the time it is not generating power. Can’t we use the same logic to see that smooth pedaling isn’t essential to get the job done?

No one is saying or implying that smoothness is bad or should be avoided. However, we should view it in proper context and not exaggerate its importance. If smoothness leads to more power that’s great -- and a separate issue to debate. In the mean time power is power -- watts are neither pretty nor ugly.

Granted a pretty and smooth 200 watts looks better and may get you kudos, but does it make you faster than an ugly 200 watts?

[Ti Designs]

When calculating power, there is no correction factor for “smoothness” or technique. Ugly watts are the same as smooth watts. Like in the roll-over minutes commercial, they spend the same.


For a force to do work it has to have movement in the direction it is being applied. In the case of cycling, when we coast we may apply a downward force to the pedal while at the bottom of the stroke, but that force does zero work, and therefore generates no power.

Power = Work / Time

So, Power = Work/Time and Work = Force x Distance.

or (power x Time)/Distance = Force.

For force to do work is must be applied in the right, or "normalized" direction, which is at 90 degrees to the crank arm. We can define the efficientcy of that transfer as COS(offset angle) where 0 degrees of offset (pushing the crank in the right direction) is 100% efficient at that crank angle while pushing at 90 degrees offset is 0% efficient.

If you replace Force with effective force, there really is a correction factor for “smoothness” or technique. The wattage reading may be the same, but the cost of production goes up. Bringing it back to real world cycling, biomechanical factors can't be ignored.

[Karin Kirk]

Granted a pretty and smooth 200 watts looks better and may get you kudos, but does it make you faster than an ugly 200 watts?

I would argue yes. A smooth 200 watts is more efficient than an ugly 200 watts. So the rider is using less of their energy to produce the 200 watts, leaving them with the ability to do so for a longer time.

Of course given the snapshot of the 200 watt moment, the answer is no. But over the course of a whole ride, the answer is yes.

[jeffg]

I would argue yes. A smooth 200 watts is more efficient than an ugly 200 watts. So the rider is using less of their energy to produce the 200 watts, leaving them with the ability to do so for a longer time.

Of course given the snapshot of the 200 watt moment, the answer is no. But over the course of a whole ride, the answer is yes.

This makes inherent sense to me.

The funny thing is that this has been debated ad nauseaum on the wattage forums for years ...

I think the old school approach makes most sense ...

"In cycling, the efficiency of the pedaling movement has not been studied in depth and has been undervalued by researchers who are more interested in the power of the “motor” (VO2max, anaerobic threshold, strength) than by the economy of exercise.

Yet past cycling tradition placed a lot of importance on the “fluidity” of pedaling, with great use of the fixed pinion both for road and track racing.
The gear ratios used on the flat were much shorter than now and required high cadences, making efficient pedaling essential since it avoids energy waste and helps protect muscle fiber, tendons and joints from problems due to overload. "

[fiamme red]

I think the old school approach makes most sense ...

"In cycling, the efficiency of the pedaling movement has not been studied in depth and has been undervalued by researchers who are more interested in the power of the “motor” (VO2max, anaerobic threshold, strength) than by the economy of exercise.

Yet past cycling tradition placed a lot of importance on the “fluidity” of pedaling, with great use of the fixed pinion both for road and track racing.
The gear ratios used on the flat were much shorter than now and required high cadences, making efficient pedaling essential since it avoids energy waste and helps protect muscle fiber, tendons and joints from problems due to overload. "Where's that quote from? "Fixed pinion"? I've never heard the term before.

[RPS]

I would argue yes. A smooth 200 watts is more efficient than an ugly 200 watts. So the rider is using less of their energy to produce the 200 watts, leaving them with the ability to do so for a longer time.

Of course given the snapshot of the 200 watt moment, the answer is no. But over the course of a whole ride, the answer is yes.Karin, I asked if ugly versus pretty watts made a rider faster, not more efficient. Also, you know that endurance is a different issue.

You should also know that my comments regarding the absolute nature of quantifying power (as in watts) came about because of comments made by others to ridicule a person for stating what is actually correct; yet unpopular to some cyclists. I don’t like it when people – even those I don’t know – are ridiculed.

By the way, do you have data to support that a pretty spin is more “energy” efficient? That’s a big claim; and I haven’t seen hard data to support it either way. In either case I think the differences must be very minor.

[jeffg]

Where's that quote from? "Fixed pinion"? I've never heard the term before.

The (in)famous Dr. Ferrari

[fiamme red]

This page explains "fixed pinion" in Babelfish English:

http://www.speedylook.com/Fixed_pinion.html

The assembly with pinion fixes is a particular assembly of the bicycle when the pinion of the aft wheel which is generally assembled with a free Roue is assembled without free wheel what makes it interdependent of the wheel in both sens.

When one mounts a bicycle with fixed pinion, one is generally surprised to have his trained legs when one wants to slow down. It is not possible any more to make free wheel, one is obliged to continue to turn the legs until the arrêt.

The fixed pinion is used much by the racing cyclists: it is obligatory for the pistards and it is very useful for the truck drivers when they make their drive of winter.

On the track

The fixed pinion assembly is obligatory and necessary on the track. This led the trainers to hold the balance of their runners when they tighten their toe-clips before the departure and to receive them just before they stop after the races.

For the sprinters, it is the fixed pinion which makes it possible to carry out the "balances" who are always very spectacular moments, which would not be possible with wheel-free. Balance makes it possible to force the other to pass in front of what will become a disadvantage at the time of final packing.

In the other disciplines the fixed pinion makes it possible to reduce the bicycles of all that is useless and to put all the runners at equality of configuration, thus obliging them to show of swiftness or endurance to impose itself.

With the drive

Certain road runners are involved in winter with a fixed pinion to improve the swiftness. The pinion fixes constrained the cyclist to pedal without stopping. Under these conditions, one cannot make differently than to pedal in round-off, if not the style becomes jerked and Déhanché. At the beginning of season, after having traversed 1000 to 1500 km with a fixed pinion, it is possible to find a pédalage flexible and harmonious.

Other uses of the fixed pinion

In the Sports shirt with bicycle: To practice this sport fixed pinion bicycles and flat handlebar are used. The fundamental rule is prohibition to play the ball and to put a foot at ground at the same time. Because of his fixed pinion, the player can dribbler, to juggle or play the ball with his roues.
The bicycles monoroues of circus are also equipped with fixed pinions to make return tickets on the spot.

[Karin Kirk]

Karin, I asked if ugly versus pretty watts made a rider faster, not more efficient. Also, you know that endurance is a different issue.

Right, which is why I gave two answers, one for the snapshot and another for the longer term. I do believe it's faster over the longer term. I also believe that's relevant to the discussion, even if you're talking about a 200m sprint, the watts still have to be sustained over the whole stretch. Maybe we need a clarification of exactly what you mean by "faster." Faster when?

I'll restate that in the instantaneous moment, they are the same, of course.

I didn't say "pretty" I said "smooth." A recent threshold test included values for efficiency of my pedal stroke, which is very interesting to look at. That is the factor I'm talking about. No I don't have data handy. I won't debate this further, I'm just writing what seems to be intuitive.

[Ti Designs]

The least smooth (roughest) power generating item I use on a regular basis is my 5-HP single-cylinder 4-stroke lawn mower. What makes it rough is that it fires only once every two revolutions, hence once every 720 degrees of rotation (by comparison even poor cyclist “fire” once every 180 degrees making their power delivery far smoother). The engine’s power stroke is limited to no more than 180 degrees of rotation, right? Therefore, actual power is generated no more than ¼ of the time; the other ¾ plus of the time there is actually “negative” power being generated (due to friction). When averaged, however, it all works out to 5-HP. That means that during the ½ revolution of the power stroke the instantaneous power generation exceeds 20-HP, but when averaged over two revolutions it comes out to 5-HP. Does anyone really care that most of the time nothing productive is taking place?


I think it's time to define both smooth and efficient 'cause they're not the same. The example of any cylinder within an internal combustion motor which is both well fuled and well timed may not be smooth, but it is efficient. While the power stroke is only one half of the two trips the piston takes up and down the cylinder, the thermal expansion should be putting peak force on the piston at a 90 degree crank angle. There is some power subtracted from the system in the other three strokes, most of it happening in the compression stroke. To get a better feel for that, turn the crank (with the plug wire off), then take out the spark plug and do the same.

In cycling it's easy to pedal "ugly" but be efficient. My glutes isolation exersize springs to mind. Eliminate all other muscles and only drop your body weight into the pedal from 1:30 to 4:30, using your glutes to support your weight. You're basicly acting like a car engine, only pushing down when the crank is in the right range to transfer power to the rear wheel. But it's far more common for people to ride "ugly" and be very inefficient. When I work with new riders I see them try to push harder on hills, which their body translates to pushing longer, and they wind up pushing down as the pedal is coming up. In motorhead speak that's called detonation, which oddly enough is what new riders tend to do mid hill. If you can pedal at 200 watts with this inefficientcy in the pedal stroke you can pedal at greater than 200 watts without it.

[happycampyer]

FOOD FOR THOUGHT

Since the effect of pedaling smoothness is what led to this thread, I’d like to use an extreme yet easy to visualize non-cycling example of non-uniform power delivery to question the technical importance of smoothness and the influence it may have on the ultimate goal (i.e. – to generate enough power to accomplish an intended task).

The least smooth (roughest) power generating item I use on a regular basis is my 5-HP single-cylinder 4-stroke lawn mower. What makes it rough is that it fires only once every two revolutions, hence once every 720 degrees of rotation (by comparison even poor cyclist “fire” once every 180 degrees making their power delivery far smoother). The engine’s power stroke is limited to no more than 180 degrees of rotation, right? Therefore, actual power is generated no more than ¼ of the time; the other ¾ plus of the time there is actually “negative” power being generated (due to friction). When averaged, however, it all works out to 5-HP. That means that during the ½ revolution of the power stroke the instantaneous power generation exceeds 20-HP, but when averaged over two revolutions it comes out to 5-HP. Does anyone really care that most of the time nothing productive is taking place?

My question is this: Because power is generated intermittently only ¼ of the time or less, does it mean that only ¼ of the grass I run over gets cut? Of course not. We know that the average is what counts because there is enough energy stored in the flywheel effect of the engine and blade to keep the mower running “well enough” to do its intended job during the other ¾ of the time it is not generating power. Can’t we use the same logic to see that smooth pedaling isn’t essential to get the job done?

No one is saying or implying that smoothness is bad or should be avoided. However, we should view it in proper context and not exaggerate its importance. If smoothness leads to more power that’s great -- and a separate issue to debate. In the mean time power is power -- watts are neither pretty nor ugly.

Granted a pretty and smooth 200 watts looks better and may get you kudos, but does it make you faster than an ugly 200 watts?More food for thought: Many, many years ago I coached a lightweight crew (small program—one eight-man boat). In the spring, I drilled them on technique—rowing with square blades, learning to accelerate together, avoiding “checking” the boat (clean catch, release, smooth recovery), etc. They hated me. 4 - 6 weeks later, they did a 20-minute piece against the heavyweights, and the lightweights steadily pulled away from them. Why? They weren’t generating more power, not by a long shot—they were rowing more efficiently.

In my experience, sloppy rowing technique works against you more than sloppy pedaling technique does, but it amounts to the same thing—wasted energy.

Also, using the wrong/weaker muscles to produce power will result in greater and earlier onset of fatigue and, at some point, will limit the amount of improvement one can achieve.

[Tobias]

For force to do work is must be applied in the right, or "normalized" direction, which is at 90 degrees to the crank arm. We can define the efficientcy of that transfer as COS(offset angle) where 0 degrees of offset (pushing the crank in the right direction) is 100% efficient at that crank angle while pushing at 90 degrees offset is 0% efficient.Your assumption referring to the angle a force is applied seems correct when analyzed for how much torque it creates about the crank axle, but I’m not sure I can agree with your definition of “efficiency” if applied beyond force utilization. Your implied premise that it reduces “energy” efficiency by the same amount is not the same, and may not be valid. Actually, I suspect it is not valid.

As stated previously, forces and work are different. Efficiency is even more complex to evaluate IMO.

[dauwhe]

I think there's lots of confusion between the power input into the rear hub, and the metabolic cost to the rider.

Dave

[Tobias]

I think there's lots of confusion between the power input into the rear hub, and the metabolic cost to the rider.

DaveConfusion in what sense? It seems to have started over whether smooth watts were faster than ugly watts, and when that was challenged by the technical guys, the argument shifted to something like OK, they are the same, but it will cost more energy to do the same work. :rolleyes:

As one on the technical side of the discussion, I think it's not so much about confusion as shifting the battleground.

[dauwhe]

Confusion in what sense? It seems to have started over whether smooth watts were faster than ugly watts, and when that was challenged by the technical guys, the argument shifted to something like OK, they are the same, but it will cost more energy to do the same work. :rolleyes:

As one on the technical side of the discussion, I think it's not so much about confusion as shifting the battleground.

I think some people are seeing the system as just the bicycle, with the rider inputting X watts. I think some people are looking at the rider, exerting themselves at a certain level (measured perhaps by blood lactate), and arguing that the same level of exertion can result in different amounts of power applied to the bicycle based on pedal stroke, etc.

Dave

[Ti Designs]

Your assumption referring to the angle a force is applied seems correct when analyzed for how much torque it creates about the crank axle, but I’m not sure I can agree with your definition of “efficiency” if applied beyond force utilization. Your implied premise that it reduces “energy” efficiency by the same amount is not the same, and may not be valid. Actually, I suspect it is not valid.

If we leave the biomechanics out of this (looking at force, direction and crank angle only), the power at the crank is the integration from 0 to 360 degrees of exactly that with respect to time - it's really not rocket science. Efficientcy is simply the ratio of power output to power output - loss.

Where it gets complicated is when we take into account biomechanics. The best example of this would be the tendency to use the quads too long. In fittings I'll stop the pedal at 3:00, and have the rider look down at their foot and try to push down on the pedal. Most of the time the quad fires. The quad extends the leg at the knee, so the resulting force vector is forward, but the pedal is traveling at 90 degrees to that. The only reason there's any downward force at all on the pedal is the increase in distance from the hip to the foot, but that's an expanding triangle system which also lacks efficientcy. Let's take it one more step. The people who use their quads from the top of the pedal stroke to the bottom also tend to complain their quads are burning on hills. With a 50% duty cycle, the muscles get blood flow at most 50% of the time, the arobic activity isn't sustainable and there's a resulting lactic acid build-up which in turn limits the wattage at the wheel.


What I don't get is the idea that how you pedal the bike can't be changed. I work with two types of riders, ones who are naturally strong and ones who aren't. The ones who start out strong often refuse to work on technique, instead using strength and effort to keep up. The ones who start out slow tend to work on technique first ('cause they foolishly listen to me), and then add power later. They also tend to race better than the ones who started out stronger and get injured less often.

[sloji]

My first thought is powerbars but they suck, my second thought was bacon (as a reconstituted vegan) and chocolate and on my long rides I found this;

[Tobias]

If we leave the biomechanics out of this (looking at force, direction and crank angle only), the power at the crank is the integration from 0 to 360 degrees of exactly that with respect to time - it's really not rocket science. Efficientcy is simply the ratio of power output to power output - loss.I agree that calculating the torque (and therefore power if speed was known) based on known forces applied to the pedals is easy enough. However, efficiency is another matter entirely and I doubt you or anyone else on this forum can calculate it. It’s not doable in my opinion. The only way to estimate efficiency is to measure it.

Ti, I’m not trying to be disrespectful, but I believe your assumption(s) on the way forces acting on the pedals at different angles affect pedaling efficiency are not correct; or at least not entirely correct. If we take the human factor out of it as if a mechanical actuator took the place of a rider’s leg doing the work, I could easily show that your assumptions don’t support the entire picture.

I wish I could discuss it further but a forum is not the right place -- it’s too complicated a subject. Besides, I could only show that your assumptions are not entirely applicable, not that I can solve the problem. As I said, I don’t think efficiency can be estimated by calculation – only estimated through testing.

[RPS]

If we take the human factor out of it as if a mechanical actuator took the place of a rider’s leg doing the work, I could easily show that your assumptions don’t support the entire picture.IMO there is an easier way to visualize the difference and show that the two are not the same; that is, the efficient use of a force to create torque is not the same as the efficient use of that force to conserve energy (hence efficiency excluding biomechanical differences).

Visualize a pedal with the crank straight up at 12 o’clock – let’s call that position 0 degrees. If we apply a 100 pound force directed straight down at all times (like if we hung a 100-pound weight off the pedal from below) and allow the crank to rotate from 12 o’clock to 6 o’clock (i.e. – from 0 to 180 degrees) we can see that at 0 and 180 degrees there is no torque produced. On the other hand maximum torque is created at 90 degrees; and is equal to 100 pounds times the crank length. For purposes of visualization, at 45 and 135 degrees the torque is about 70 pounds times the crank length. Therefore, the effectiveness in creating torque is dependent by the sine of the angle (as described for the example above). It starts at zero torque at 0 degrees, builds up to a maximum at 90 degrees, and ends back at zero at 180 degrees.

Looking at energy conservation is much different. The amount of energy supplied by the weight which is turned to work while rotating the crank is 100 lbs X 2 X crank length. This is equal to the change in potential energy due to elevation of a 100 pound weight going from 0 to 180 degrees.

If we integrated the process, we’d find that all energy can be accounted for and that it is converted to useful work. The fact that the torque starts and ends at zero does not affect energy conversion (I’m avoiding using the word efficiency on purpose). To me it makes sense that all energy (except for very minor bearing losses) ends up as work because where else would it go?

My personal conclusions are two: First that applying forces to the pedals at odd angles does not in itself inherently create mechanical inefficiency. Applied rider-produced work – even at odd angles -- just doesn’t dissipate into thin air.

Secondly, almost all inefficiency has to be due to rider biomechanical efficiency differences. To me this doesn’t mean what has been implied in previous posts. If a rider pushes down on the pedal and does 50 lb-ft or work, IMO almost all of that ends up in useful work being done regardless of angles. Rider effort and the amount of calories he/she may have to burn to produce that 50 lb-ft of work is another matter – and one that can’t be calculated or estimated based on angles.

Just my 2 cents. ;) And please note I have not made a case in this post or previous ones for having a poor or ugly spin. I like smoothness.

[Tobias]

Over the last couple of days I’ve tried to visualize a single scenario where the non-biomechanical portion of pedaling could lead to lower efficiency. OK, I’ve been bored – really bored.

It’s not hard to visualize a very inefficient pedal stroke. If I imagine the right crank at 3 and the left one at 9 o’clock and push on the right pedal with 100 pounds and on the left one with 50 pounds, I can see that as I pedal a tiny bit forward the amount of work done towards powering my bike is only 50% of what it would be if the left leg was not pushing down on the left pedal as it moved up.

Where it gets complicated is that if we exclude all biomechanical factors and look at what took place as if it was a machine, we have to account for negative work done on the left leg. Basically, half the work done by the right leg onto the bike is fed back from the bike back to the left leg. For most of us the concept of negative work is hard to understand, but it has to be accounted for. If not, we wouldn’t be able to account for where energy ends up.

The problem is that when “work” is done to our bodies the energy isn’t stored for future use in an efficient way – it’s basically wasted. This is very different than machine components like a spring, flywheel, etc… When we do work on a spring by compressing it, or a flywheel by spinning it up, that energy is stored for future use. This is not the case with our bodies. As an example, when we walk downstairs or downhill work is done to us, but that energy isn’t stored to help us go back up. It’s wasted.

From my perspective pedaling inefficiencies must be limited to biomechanics. And that’s a good thing for me because it leaves a lot of room for improvement. OK, now that I’ve rationalized :rolleyes: where the extra energy that goes into a bad spin ends up; it’s time to watch football.