Road Bike Racing - How come torque output isn't used in power training?

I see watt reading all the time when referring to power training and test improvement but never a mention of torque. This only occurs to me as I have been looking at my PT data(which I am very new to) and the torque figures are higher and watt numbers lower when I use a bigger gear and slower cadence. It seems like the big non-spinner guys would make more out of this, or it may be just my perception.

Power is more important for sustaining speed. Torque is more important for accelerating. I have no power meter (grumble) but I'm sure there's an analysis of it somewhere out there.

In the auto arena, they always say "Power is what you read about, but torque is what you feel." Acceleration is more important for selling cars than for road racing bicycles :)

I'd certainly train to improve torque -- I'll bet form can have a huge impact on it.

I've been visually tracking crank torque after each ride, but to be honest I'm unsure what to do with the data. I've done a lot of reading about power training so far, and have yet to see anything related to making the torque numbers a part of your workout.

I have noticed, though, that with my new position, with uses much more of the glutes and hip flexors, that my average torque for a ride seems to have gone up. What any of this means, I don't know.

and the torque figures are higher and watt numbers lower when I use a bigger gear and slower cadence.

power = torque * speed.

Power is more important for sustaining speed. Torque is more important for accelerating.

complete bull****.

Training and Racing with a Power Meter suggests that you track your torque figures in concert with your power. If you see torque go up, and power go down - you probably let your form go, such as when you're getting tired.

The idea is more power at lower torque, just like with heart rate.

to answer the question torque isn;t used because it is meaningless as far as performance goes.
Power shows how much work you are doing per unit time. That is what is important torque just shows how hard you are pushing on the pedals x what direction you are pushing. If you exclude how fast you are moving your feet this number is pointless.

to answer the question torque isn;t used because it is meaningless as far as performance goes.
Power shows how much work you are doing per unit time. That is what is important torque just shows how hard you are pushing on the pedals x what direction you are pushing. If you exclude how fast you are moving your feet this number is pointless.

Are you sure? See my last post...

The idea is more power at lower torque, just like with heart rate.

that purely means spinning your feet faster(or moving faster if it is measured at the hub). Cadence would tell you the exact same thing.

that purely means spinning your feet faster(or moving faster if it is measured at the hub). Cadence would tell you the exact same thing.

Form is impacted by more than cadence. I don't know if getting sloppy on your bike impacts torque or not though...if it did it'd be more useful. Is cadence the only factor that determines torque readings?

Form is impacted by more than cadence. I don't know if getting sloppy on your bike impacts torque or not though...if it did it'd be more useful. Is cadence the only factor that determines torque readings?

cadence is the only factor in dertimining the tourque/power ratio(assuming we are talking toque at the crank if it's torque at the rear wheel then bike speed is the only factor.) Either way it seems like a useless number to me.

If you have bad form you can apply non-tangential force which will make torque decrease but so will power everywhere(since your foot is always moving tangentially). Short of a force sensor in your cleat or something you are never going to be able to measure this ineffinciency.

Torque is the twisting force applied to an object.

Work is the application of force over a distance.

Power is the application of work over a defined period of time.

Also, here is a link with pics to help describe it:
http://hyperphysics.phy-astr.gsu.edu/Hbase/torq2.html

Here's a problem with comparing torque measurements between riders: from the pics in the link above, you can see that the length of the lever arm determines the torque applied to an object for a given application force. Now, think of the lever calculations required for your bike... crank length - easy, foot length - ok, length of your upper leg - difficult to measure from rotating point to rotating point. Then you have to take into account the rotational angle the force is applied at. Since the angle continuously changes, you would need to calculate the torque throughout the 360 degree rotation.

All this to give what...? It doesn't tell you how hard your body is working. It doesn't tell you how efficient you are working.

Basically, measuring your power in watts is a direct method of determining your work output. How you set your bike up (crank length) and how your genetics set you up (height) are part of how your watts are converted to speed. So, what you really want to know is power in watts.

complete bull****.
You disagree with someone and immediately go rude? Oh, right, this is the internet.

So why can I easily outsprint an economy car for a block, but it can go 110mph, while I can only sustain 26mph?

I weigh 1/10 as much but have 1/200 as much power. I happen to have more torque (~171 lb-ft with a 175mm crank vs. an econo car at ~120 lb/ft).

Look at it another way: in a given gear, you can accelerate faster with a longer crank -- which increases your torque.

torque is also an instantaneous measure, whereas power cna be taken for any interval of time you choose.

To give my take on Snuff's ideas: you might have a higher peak torque in your pedal stroke for the same power if your form is falling apart. Think smooth versus choppy pedal stroke. This is a potential use for torque.

Another way to use it is avg. torque over a very short time period instead of 1 sec or 5 sec power. It might track more accuretly with your muscles ability to produce power at the pedals (if, in fact, you want to measure this)

power = torque * speed.

That would mean that power units are Nm / (m/s) = Nm * (s/m) = Ns

But power is Work/Time = Nm/s

Power = Work / Time = (Force * Distance) / Time
Torque = Force * Distance

So, Power = Torque / Time, not Torque * Speed

Yes, torque & power are related as power is torque integrated with respect to time. waterrockets equations above is spot on. It's similar to a more familar progression of speed & distance that you may be more familar with:


acceleration = speed / time = distance / time / time
power = torque /time = force * distance / time

If you take derivatives and simplify each term you get


acceleration -> speed -> distance
power -> torque -> force

You can't use torque & power interchangeably because they are only related as an integration or derivative with respect to time. It's like an officer asking you how fast you were going and you answer with, "I was at 100ft.".

In the bicycling sense, torque isn't as useful a measure as power because you don't know for how long and how quickly that torque was applied. And torque at crank is also divided out by the gearing, so that the same torque ends up as different torque at the rear wheels depending upon gearing. Case in point:


Rider#1 = 100 lb*ft @ 100rpms = X power = Y speed
Rider#2 = 100 lb*ft @ 130rpms = A power = B speed

Rider #2 is putting out the exact same force on the cranks and has exactly the same torque as rider#1. However, since he's in a lower gear and spinning faster, he's going to generate 30% higher power and will be going at a faster speed. A > X and B > Y

Yes, torque & power are related as power is torque integrated with respect to time. waterrockets equations above is spot on. It's similar to a more familar progression of speed & distance that you may be more familar with:


acceleration = speed / time = distance / time / time
power = torque /time = force * distance / time

If you take derivatives and simplify each term you get


acceleration -> speed -> distance
power -> torque -> force


With due respect, your analogy is not only confusing, but incorrect (hint: you are not deriving consistantly). Bonus points provided to the first person to replace 'force' with the correct term.

A better one is to compare linear and rotational systems:

Linear: Power = Force * Linear Velocity
Angular: Power = Torque * Angular Velocity (Cadence at the BB)

While torque is related to acceleration of the bike (thanks to a little invention known as the wheel), the gearing system really complicate things. You can always increase your torque at the BB simply by downshifting, but this can translate into less force where the wheel meets the pavement, which is what _really_ accelerates the bike.

Short of a force sensor in your cleat or something you are never going to be able to measure this ineffinciency.

You mean like this:

http://www.microsporttech.com/technical.php

That would mean that power units are Nm / (m/s) = Nm * (s/m) = Ns

But power is Work/Time = Nm/s

Power = Work / Time = (Force * Distance) / Time
Torque = Force * Distance

So, Power = Torque / Time, not Torque * Speed


speed in the case of a rotating object is radians(unitless)/s not m/s. Using anything else is completely nonsensical.

You mean like this:

http://www.microsporttech.com/technical.php


more or less but to truly gauge inefficiency it would have to be multidirectional.

torque is also an instantaneous measure, whereas power cna be taken for any interval of time you choose.

To give my take on Snuff's ideas: you might have a higher peak torque in your pedal stroke for the same power if your form is falling apart. Think smooth versus choppy pedal stroke. This is a potential use for torque.

Another way to use it is avg. torque over a very short time period instead of 1 sec or 5 sec power. It might track more accuretly with your muscles ability to produce power at the pedals (if, in fact, you want to measure this)

or very simply you could have a rider that produces better torque at lower rpm and uses it vs a rider with less torque and has a higher cadence

seems like the equation:
power=(torque*rpm)/5280

will yield horsepower

cant remember if thats it or not, been awhile since I took physics

anyway, at the racetrack with cars, torque is indeed what provides acceleration, two cars with the same hp and weight but different torque output will yield different times, it has to, its a linear equation

problem is with bikes your dealing with tiny little numbers and relative small rpm ranges

more or less but to truly gauge inefficiency it would have to be multidirectional.

You mean, like this:

http://www.microsporttech.com/faq.php

http://www.microsporttech.com/images/clock.gif

speed in the case of a rotating object is radians(unitless)/s not m/s. Using anything else is completely nonsensical.
It's a trivial multiplication of a constant to convert to R/s and doesn't change anything.

It's a multiplication of a constant to convert to R/s and doesn't change anything.

indeed. The point is you tried to use m/s as speed in an equation with torque. That is simply absurd. I suppose I could have been more exact and said angular velocity but I(apparently correctly) figured that not everyone here had a firm grasp on high school physics.

problem is with bikes your dealing with tiny little numbers and relative small rpm ranges

Also(unless we move over to the track forum) bikes have a huge number of gears. All of waterrockets torque at the crankset numbers are pointless because the other rider can just shift down.

For example take two riders, one who can spin and one who can't are trying to accelerate a given amount. The one that can't spin might be able to apply much more torque then the other one but if his power is less due to the fact that he moves his feet slower he will not accelerate as fast. Of course we could also say that his torque at the rear wheel will always be lower at a given speed because at that point the number are completely interchangeable.

You mean, like this:

yep pretty much exactly but that isn't what the cleat you buy actually does. Their whole system is based on their(questionable) finding that everyone pedals with the same efficiency.

indeed. The point is you tried to use m/s as speed in an equation with torque. That is simply absurd. I suppose I could have been more exact and said angular velocity but I(apparently correctly) figured that not everyone here had a firm grasp on high school physics.
Whatever. The curves would all still be the same shape. Please excuse my typo.

At least I didn't try to say Power = Torque * Speed

At least I didn't try to say Power = Torque * Speed

But it does. As I pointed out before the only meaningful speed in relation to torque is angular velocity. Anyone with a slight grasp of HS physics knows that.

power = torque * angular velocity
since in this case angular velocity = speed
therefore
power = torque * speed.

You made a further point about torque being meaningful for acceleration while power is meaningful for top speed. This is an abstraction that is meaningful on cars due to the power and torque vs rpm functions of the engines and the available gears. In general it is not true and it is meaningless for bikes.

So why can I easily outsprint an economy car for a block, but it can go 110mph, while I can only sustain 26mph?


Well, gearing multiplies torque for both you and the car, I'm not really sure what the final gearing would be in a car (I could figure it out, but off the top of my head I have no idea how an economy car is geared in the tranny and final drive and also wheel size).

You must have pretty small blocks compared to where I live. Or you're really fast. Or the drivers aren't actually trying to beat you. Considering how fast most economy cars are today (I have no doubt you could beat a Beetle or something similar)- most of them could easily get up to professional-level sprinting speeds in a couple hundred yards. Of course some cars can get to 60 in a couple hundred feet (sports cars) - most anything can do it in a few hundred feet if the driver actually tries (no idea why you would do this....)

Well, gearing multiplies torque for both you and the car, I'm not really sure what the final gearing would be in a car (I could figure it out, but off the top of my head I have no idea how an economy car is geared in the tranny and final drive and also wheel size).

You must have pretty small blocks compared to where I live. Or you're really fast. Or the drivers aren't actually trying to beat you. Considering how fast most economy cars are today (I have no doubt you could beat a Beetle or something similar)- most of them could easily get up to professional-level sprinting speeds in a couple hundred yards. Of course some cars can get to 60 in a couple hundred feet (sports cars) - most anything can do it in a few hundred feet if the driver actually tries (no idea why you would do this....)
My point isn't so much that I can beat them or not, but that it's even close at all in a 100m event. Top speed isn't anywhere near close, neither is horsepower. Torque at the engine is close, and so is the low-end sprint result.

Consider a dump truck if you have to -- nearly anyone can keep up with one of those for 100m, but nobody can on the highway.

So why is this true?

Torque at the engine is close, and so is the low-end sprint result.

That is just a coincidence because of gearing. Power to weight ratio is what matters in what matters your race. That torque at the engine works out that way is just dumb luck.

That is just a coincidence because of gearing. Power to weight ratio is what matters in what matters your race. That torque at the engine works out that way is just dumb luck.

Ok, so what about a really low horsepower car, like an old diesel golf, that has a lot more torque, and that I can't beat? (I have a friend with one and we raced across a parking lot)

The golf has approximately the same gearing as any other econo car.

Ok, so what about a really low horsepower car, like an old diesel golf, that has a lot more torque, and that I can't beat? (I have a friend with one and we raced across a parking lot)

The golf has approximately the same gearing as any other econo car.

Probably because you friend knows how to drive it and was actually racing you. The people at the stop lights don't know what's going on and aren't going to launch their car to try to beat you.

Also, a diesel Golf (the older ones) makes considerably less torque than a modern 110ft/lb economy car. Their max torque is in the 70's IIRC. If you're talking about the TDIs, they have gobs of torque, but also a good amount of Hp (90-100, whereas the non TDIs had like 50).

A dump truck makes a ****-load more torque than either you, the diesel golf, or a sports car.


Again I think you're not calculating torque at the drive wheels, which is what really counts. Cars really aren't geared to accelerate as fast as possible to bicycle-sprint speeds. I have an old 4x4 that you would certainly beat on the street (non-synchro gearbox, etc, etc- slower than an economy car despite having 185hp and 235ft lb of torque). But if I put the transfercase in low-range the torque at the wheels goes WAY up. Of course I'm going to top-out at like 35, but if it was a 5 speed with similar gearing instead of a 3 speed....

I reiterate what I think and that is that you probably can't beat even an economy car. I know your counter to that was to consider a dump truck - but that falls apart because they have tremendous torque. The issue there is 1. they weren't racing 2. they have a LOT of gears 3. they may have been weighed down.

<snipped a bunch of stuff I generally agree with>
I reiterate what I think and that is that you probably can't beat even an economy car. I know your counter to that was to consider a dump truck - but that falls apart because they have tremendous torque. The issue there is 1. they weren't racing 2. they have a LOT of gears 3. they may have been weighed down.
Thanks for continuing to respond -- I'm not trying to argue as much as understand.

I guess that I still see a massive difference at cruising speed, but not at takeoff. A car, even not racing, will go 60mph on the highway. No challenge. From a light, not racing, I can keep up if I'm going all out. Once we're up to speed, I can't even come close to keeping up when I'm going all out.

Is torque not the difference here?

If gearing explains it, then wouldn't that be a torque argument? I'm starting my engine at 0 rpm, but I happen to have a lot of torque at that point in the curve. When a car gets up to 2000-3000 rpm, even just driving normally, the torque can go way up depending on throttle position.

Thanks for continuing to respond -- I'm not trying to argue as much as understand.

I guess that I still see a massive difference at cruising speed, but not at takeoff. A car, even not racing, will go 60mph on the highway. No challenge. From a light, not racing, I can keep up if I'm going all out. Once we're up to speed, I can't even come close to keeping up when I'm going all out.

Is torque not the difference here?

If gearing explains it, then wouldn't that be a torque argument? I'm starting my engine at 0 rpm, but I happen to have a lot of torque at that point in the curve. When a car gets up to 2000-3000 rpm, even just driving normally, the torque can go way up depending on throttle position.

Acceleration:
power to weight ratio.
Top speed:
Power to aerodynamics.

Torque is a red herring here. What matters is power since it is not effected by gearing but the riders strength/endurance. Torque at the rear wheel tells us nothing about the rider and so is worthless.

Also I'm willing to bet your engine has hardly any torque at 0rpms.

Thanks for continuing to respond -- I'm not trying to argue as much as understand.

I guess that I still see a massive difference at cruising speed, but not at takeoff. A car, even not racing, will go 60mph on the highway. No challenge. From a light, not racing, I can keep up if I'm going all out. Once we're up to speed, I can't even come close to keeping up when I'm going all out.

Is torque not the difference here?

If gearing explains it, then wouldn't that be a torque argument? I'm starting my engine at 0 rpm, but I happen to have a lot of torque at that point in the curve. When a car gets up to 2000-3000 rpm, even just driving normally, the torque can go way up depending on throttle position.

No, torque is not the difference. Although I wouldn't say it is power to weight ratio either. Somebody else can figure it out, but I bet even with a good 30s power a human + bike has a worse power/weight that a car. Although the car isn't making anywhere NEAR max power... The other thing relating to power is that the car is starting at an RPM where is makes basically no power (idle), whereas our "engines" can produce good power off of 0rpms - especially for short periods of time. It takes a few seconds for that car (especially one that isn't racing and is just accelerating normally) to get into the power band. Most people can drive around calmly through town only using a few dozen horsepower, seriously. Look at a dyno graph of *most* cars and you'll see that in the sub-2000rpm range where most people who don't like paying for gas drive you have very little power. But its enough for scooting along the road. Of course cars with small turbos, diesels, turbo diesels, and some large-displacement truck-type petrol motors are excepted from that. But the typical 4 banger economy car has a really spikey power curve, making most of its power near redline. Which is why when you try to pass in one of these cars they/you have to downshift and rev the hell out of them.

Can I step in? Let's back up here, and forgive me if this is too simplistic -- I don't mean to insult anyone's intelligence (I tried that in my other post and no one bit ;) )

The acceleration of the bike is determined by the force applied by the wheel where it meets the road divided by the weight of the rider (ignoring the other forces such and wind, etc.). This force is related to torque by the gear-inches:

Force at the Road = Torque / Gear Inches ... (times some factor to make all the units match up)

So, if you switch to a higher gear, the same amount of torque generates _less_ force and _less_ acceleration. The converse is also true: a lower gear will generate more force. In addition, for any given gear, the acceleration is proportional to torque. Thus, for two riders riding at the same cadence, if they both initiate a sprint, the one with more torque will accelerate faster.

Now, the weaker rider might think "Well, if I just downshift, I can generate more force at the same amount of torque, and I will win!" The trouble is, of course, if you choose too low of a gear, your legs aren't able to 'keep up' with the pedals. That is, you cannot spin fast enough for the given amount of torque. Cadence times torque is power. So this is where power, _in addition to torque_, becomes important in acceleration.

that purely means spinning your feet faster(or moving faster if it is measured at the hub). Cadence would tell you the exact same thing.

That's how a PT works: Power = Cadence * Torque

That's how a PT works: Power = Cadence * Torque

That might work for srm but would be a meaningless number with a PT.