Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 11:15

Post #51 of 160 (3922 views)

Slowman wrote:

i guess i'm ambivalent. i hear you. i don't know that there's a practical difference given, as rchung stated, that there really is not that much difference between crank lengths for the purposes of torque (yes, for the purposes of range of motion, less for torque).

but, yeah, if power = torque x cadence and max torque = force x lever arm when that force is perpendicular to the lever arm? something like that? then, yes, i could see how force is what i'm after.

the reason i kind of like torque, tho, is that i know power, and i know cadence. i don't know torque. as a cycling metric. so, i'd like to see how torque and cadence act, inversely. i see your point. but i don't think it would be that different looking at force versus torque, and what is certain is that i can have torque easily from any device i own with pretty little extra work from that device maker.

If comparing across athletes or even bikes, I see how it would be useful to know torque as well as force. If it is just you in your basement on your trainer, torque vs. force doesn't matter. If you know your power and your cadence, you could make up some imaginary torque unit and ride to that.

Is this what you are thinking like when you are trying to look at torque based training: riding at 50rpm and 100 watts, and you could be producing 20 slowmans (of torque). 75 rpm and 150 watts = 20 slowmans. 75 rpm and 300 watts = 40 slowmans?

Oui, mais pas de femme toute de suite (yes, but I am not ready for a woman straight away) -Stephen Roche's reply when asked whether he was okay after collapsing at the finish in the La Plagne stage of the 1987 Tour

Re: Calling all Coggans [Vincible] [ In reply to ]

Mar 21, 18 11:21

Post #52 of 160 (3920 views)

Vincible wrote:

Slowman wrote:

i guess i'm ambivalent. i hear you. i don't know that there's a practical difference given, as rchung stated, that there really is not that much difference between crank lengths for the purposes of torque (yes, for the purposes of range of motion, less for torque).

but, yeah, if power = torque x cadence and max torque = force x lever arm when that force is perpendicular to the lever arm? something like that? then, yes, i could see how force is what i'm after.

the reason i kind of like torque, tho, is that i know power, and i know cadence. i don't know torque. as a cycling metric. so, i'd like to see how torque and cadence act, inversely. i see your point. but i don't think it would be that different looking at force versus torque, and what is certain is that i can have torque easily from any device i own with pretty little extra work from that device maker.

If comparing across athletes or even bikes, I see how it would be useful to know torque as well as force. If it is just you in your basement on your trainer, torque vs. force doesn't matter. If you know your power and your cadence, you could make up some imaginary torque unit and ride to that.

Is this what you are thinking like when you are trying to look at torque based training: riding at 50rpm and 100 watts, and you could be producing 20 slowmans (of torque). 75 rpm and 150 watts = 20 slowmans. 75 rpm and 300 watts = 40 slowmans?

well, you're not producing slowmans. you're producing foot-pounds. and it's not imaginary. it's actual foot-pounds, or newton-meters, or whatever. i can derive this through known values, cadence and power, and i'll know it to plus/minus 1.5 percent or if i can't then my smart trainer or power meter is making a false claim.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 11:43

Post #53 of 160 (3898 views)

Slowman wrote:

well, you're not producing slowmans. you're producing foot-pounds. and it's not imaginary. it's actual foot-pounds, or newton-meters, or whatever. i can derive this through known values, cadence and power, and i'll know it to plus/minus 1.5 percent or if i can't then my smart trainer or power meter is making a false claim.

...and then you take that same number and just divide by your crank length (a constant for a given setup and session, right?), and you have force...which is what your legs are actually producing/feeling.

http://bikeblather.blogspot.com/

Re: Calling all Coggans [Tom A.] [ In reply to ]

Mar 21, 18 11:46

Post #54 of 160 (3892 views)

Tom A. wrote:

Slowman wrote:

well, you're not producing slowmans. you're producing foot-pounds. and it's not imaginary. it's actual foot-pounds, or newton-meters, or whatever. i can derive this through known values, cadence and power, and i'll know it to plus/minus 1.5 percent or if i can't then my smart trainer or power meter is making a false claim.

...and then you take that same number and just divide by your crank length (a constant for a given setup and session, right?), and you have force...which is what your legs are actually producing/feeling.

For peak force, yes. I don’t care. Doesn’t matter. Kind of beside the point.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Tom A.] [ In reply to ]

Mar 21, 18 11:47

Post #55 of 160 (3892 views)

Tom A. wrote:

Slowman wrote:

well, you're not producing slowmans. you're producing foot-pounds. and it's not imaginary. it's actual foot-pounds, or newton-meters, or whatever. i can derive this through known values, cadence and power, and i'll know it to plus/minus 1.5 percent or if i can't then my smart trainer or power meter is making a false claim.

...and then you take that same number and just divide by your crank length (a constant for a given setup and session, right?), and you have force...which is what your legs are actually producing/feeling.

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Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 11:57

Post #56 of 160 (3882 views)

Slowman wrote:

For peak force, yes. I don’t care. Doesn’t matter. Kind of beside the point.

Average force. However, for most of us, a reasonable rule of thumb is that peak force is roughly twice average.

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:03

Post #57 of 160 (3876 views)

Slowman wrote:

Tom A. wrote:

Slowman wrote:

well, you're not producing slowmans. you're producing foot-pounds. and it's not imaginary. it's actual foot-pounds, or newton-meters, or whatever. i can derive this through known values, cadence and power, and i'll know it to plus/minus 1.5 percent or if i can't then my smart trainer or power meter is making a false claim.

...and then you take that same number and just divide by your crank length (a constant for a given setup and session, right?), and you have force...which is what your legs are actually producing/feeling.

For peak force, yes. I don’t care. Doesn’t matter. Kind of beside the point.

Beside the point in what way? I'd argue it's the ENTIRE point.

Did you look at those QA plots from that link to my blog post? If so, what was your takeaway?

http://bikeblather.blogspot.com/

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:24

Post #58 of 160 (3851 views)

Why would you be interested in torque and not force? Torque isn’t measured. It’s calculated. Force is what’s measured by the strain gauges.

Re: Calling all Coggans [RChung] [ In reply to ]

Mar 21, 18 12:26

Post #59 of 160 (3845 views)

RChung wrote:

Slowman wrote:

For peak force, yes. I don’t care. Doesn’t matter. Kind of beside the point.

Average force. However, for most of us, a reasonable rule of thumb is that peak force is roughly twice average.

by average force are you talking about the averaging of peak force over x number of pedal cycles? or average force throughout the pedal circle? because, if the latter, extracting that is not as as simple as average torque.

average torque is simply power divided by cadence. average force, unless it's a direct measure, is not easy to tweeze out of torque. force is the diminished (if i remember) by the cosine of the angle formed by the perpendicular to peak force and the line to wherever the pedal may be at the time. or something like that. so, unless your power meter knows that angle at any given sampling moment then it's hard to extract average force. much easier to extract average torque, and much easier to extract torque at any point along the pedal circle.

Dan Empfield
aka Slowman

Re: Calling all Coggans [stevej] [ In reply to ]

Mar 21, 18 12:33

Post #60 of 160 (3831 views)

The strain gauges are actually measuring strain. From the measured strain you can calculate the bending moment, force, etc using your understanding of the structure response of the object the strain gauge is attached to.

Re: Calling all Coggans [stevej] [ In reply to ]

Mar 21, 18 12:38

Post #61 of 160 (3831 views)

stevej wrote:

Why would you be interested in torque and not force? Torque isn’t measured. It’s calculated. Force is what’s measured by the strain gauges.

two things. first, i predict that by the time we hit 100 posts no one arguing his thesis is going to remember the point of the exercise. so, for the purposes of the point of the exercise, i don't think it makes any difference. if i choose torque as the metric, and i get a wild hair and decide to move up or down 5mm in crankarm length, which i'm unlikely to do, this means a 3 percent difference. so, for the purposes of the exercise, i'd be cool with either. i would not find it a liability to get one metric over the other. right now i have neither.

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:38

Post #62 of 160 (3830 views)

Slowman wrote:

average torque is simply power divided by cadence. average force, unless it's a direct measure, is not easy to tweeze out of torque. force is the diminished (if i remember) by the cosine of the angle formed by the perpendicular to peak force and the line to wherever the pedal may be at the time. or something like that. so, unless your power meter knows that angle at any given sampling moment then it's hard to extract average force. much easier to extract average torque, and much easier to extract torque at any point along the pedal circle.

You have all this upside down. A power meter is measuring force through a strain gauge. Force is the most elemental metric. Then, it is taking force and a known distance to calculate torque. Then, it is taking the torque number and multiplying that by angular velocity. It has to take multiple force measurements per revolution in order to have a more accurate. The PM has whatever means is necessary to measure the tangential force vector. Force is the center of the universe in a PM, and it is the thing that matters to the athlete. Torque is the derivative number.

Re: Calling all Coggans [exxxviii] [ In reply to ]

Mar 21, 18 12:47

Post #63 of 160 (3811 views)

exxxviii wrote:

Slowman wrote:

average torque is simply power divided by cadence. average force, unless it's a direct measure, is not easy to tweeze out of torque. force is the diminished (if i remember) by the cosine of the angle formed by the perpendicular to peak force and the line to wherever the pedal may be at the time. or something like that. so, unless your power meter knows that angle at any given sampling moment then it's hard to extract average force. much easier to extract average torque, and much easier to extract torque at any point along the pedal circle.

You have all this upside down. A power meter is measuring force through a strain gauge. Force is the most elemental metric. Then, it is taking force and a known distance to calculate torque. Then, it is taking the torque number and multiplying that by angular velocity. It has to take multiple force measurements per revolution in order to have a more accurate. The PM has whatever means is necessary to measure the tangential force vector. Force is the center of the universe in a PM, and it is the thing that matters to the athlete. Torque is the derivative number.

righteo. there's the world we want, and there's the world we live in. if you want a device maker, or an app maker (trainerroad, let's say) to give you force, around the pedal circle - tomorrow! - how likely? if you want them to give your torque - tomorrow (or next week) - how likely? or to put it another way, if they wanted to provide this, they could tomorrow. torque! but they couldn't provide force. you're not going to get force. you'll get it, from a device maker - next year - if next week trainerroad starts producing workouts where torque is the metric, and if you all proclaim your huzzahs and torque becomes a sexy number.

so, the only way you're going to get something around the pedal circle is if that something is torque, and it's going to be a back-calculation from power and cadence. in my opinion. unless there's something i don't know or can't see, which is very, very, very possible.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:50

Post #64 of 160 (3802 views)

Slowman wrote:

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Maybe we are misunderstanding you but you seem to be trying to reverse calculate/engineer the power reading to get torque and force. You are making it way harder than it needs to be. You know Force before you know torque and you torque before you know power. No need to calculate torque and force based off watts. They are inputs to the equation to get watts so they are already known.

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:53

Post #65 of 160 (3796 views)

Slowman wrote:

righteo. there's the world we want, and there's the world we live in. if you want a device maker, or an app maker (trainerroad, let's say) to give you force, around the pedal circle - tomorrow! - how likely?

Force metrics and visualization are already happening today with PowerTap P1 pedals and their iPhone app. Unfortunately, none of head units are doing it. Per the comments above, it would not take rocket science to do either torque or force with a Connect IQ. Once you get up to a web app, torque would be the only number, since I bet that FIT files do not ship force or moment.

Garmin's Pedal Dynamics are still oriented around Power, but they clearly have all of the force vector data, because that is necessary for the visualizations. So, the nut is Garmin does not see a need to do either Force or Torque. The fact this does not exist is a Garmin HU thing. They could, and they are getting the real-time force data, but they have chosen not to present it.

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:53

Post #66 of 160 (3795 views)

Slowman wrote:

stevej wrote:

Why would you be interested in torque and not force? Torque isn’t measured. It’s calculated. Force is what’s measured by the strain gauges.

two things. first, i predict that by the time we hit 100 posts no one arguing his thesis is going to remember the point of the exercise. so, for the purposes of the point of the exercise, i don't think it makes any difference. if i choose torque as the metric, and i get a wild hair and decide to move up or down 5mm in crankarm length, which i'm unlikely to do, this means a 3 percent difference. so, for the purposes of the exercise, i'd be cool with either. i would not find it a liability to get one metric over the other. right now i have neither.

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Same is true for force (tangential effective pedal force)...they'd just need the user to enter crank length (to divide the torque by).

In fact, I plotted those QA plots I referred to above (which you still haven't told me what your take-away on them is yet...but, I digress...) using power meter data in GoldenCheetah. The only additional information needed was crank length. WKO has the same function as well.

Let me ask this...are you somewhat fixated on torque because you think you might be able to do something about it based on measurements within a pedal stroke cycle? For many reasons (I'm sure you've heard), that's not really "worthy of pursuit"...

http://bikeblather.blogspot.com/

Re: Calling all Coggans [stevej] [ In reply to ]

Mar 21, 18 12:58

Post #67 of 160 (3783 views)

stevej wrote:

Slowman wrote:

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Maybe we are misunderstanding you but you seem to be trying to reverse calculate/engineer the power reading to get torque and force. You are making it way harder than it needs to be. You know Force before you know torque and you torque before you know power. No need to calculate torque and force based off watts. They are inputs to the equation to get watts so they are already known.

okay. i'll bite. if i know force before i know torque, you also must know force too. what is the direct measured force you pedaled, on average, during your last recorded ride?

Dan Empfield
aka Slowman

Re: Calling all Coggans [trail] [ In reply to ]

Mar 21, 18 12:58

Post #68 of 160 (3781 views)

trail wrote:

MattyK wrote:

(*sort of directly. Let's not dig too deep)

Well then don't use a phrase like "actually directly measure" in front of an engineer when the more accurate phrase is "indirectly estimate." :)

As far as I can figure, a power meter's strain gauges' measurement of torque is no less a "measurement" than what a scale does to measure the weight of an object. Hang an object from a spring, make notice of how much the spring ( which you have calibrated) stretches, and you have measured weight. How is the power meter's strain gauge any different in its essence? The strain gauge measures force, and it's a trivial matter to calculate, (measure!) torque from that. Cadence itself is measured, distance, (use a ruler to measure the radius of the wheel,) vs time, (use a clock.)

Last edited by: DJFaithful: Mar 21, 18 13:04

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 12:59

Post #69 of 160 (3780 views)

Power = F X C lets say Force is torque!!!!!

200 watts = 2.0 x 100 rpm
180 watts = 1.8 x 100 rpm
160 watts = 1.6 x 100 rpm.

then all you care about is torque so you ride 2.0 like so
150 watts = 2.0 x 75 rpm

good job riding your proper race torque. I ate all the snacks before you got here slow poke.
Plus your back and Hips are sore from overloading your legs with excessive load to do the work needed.

end of discussion. Go ride practice gear x and learn to shift wt faster on gear x to increase RPM. once gear x is at a faster pace gear down and relearn on the next gear. please rinse and repeat until wt in down and power is up.

Technique will always last longer then energy production. Improve biomechanics, improve performance.
http://Www.anthonytoth.ca, triathletetoth@twitter

Re: Calling all Coggans [Tom A.] [ In reply to ]

Mar 21, 18 13:03

Post #70 of 160 (3776 views)

Tom A. wrote:

Slowman wrote:

stevej wrote:

Why would you be interested in torque and not force? Torque isn’t measured. It’s calculated. Force is what’s measured by the strain gauges.

two things. first, i predict that by the time we hit 100 posts no one arguing his thesis is going to remember the point of the exercise. so, for the purposes of the point of the exercise, i don't think it makes any difference. if i choose torque as the metric, and i get a wild hair and decide to move up or down 5mm in crankarm length, which i'm unlikely to do, this means a 3 percent difference. so, for the purposes of the exercise, i'd be cool with either. i would not find it a liability to get one metric over the other. right now i have neither.

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Same is true for force (tangential effective pedal force)...they'd just need the user to enter crank length (to divide the torque by).

In fact, I plotted those QA plots I referred to above (which you still haven't told me what your take-away on them is yet...but, I digress...) using power meter data in GoldenCheetah. The only additional information needed was crank length. WKO has the same function as well.

Let me ask this...are you somewhat fixated on torque because you think you might be able to do something about it based on measurements within a pedal stroke cycle? For many reasons (I'm sure you've heard), that's not really "worthy of pursuit"...

first, i'm not fixated on torque. i'm asking whether riding by a different metric - and either force or torque would work for me - is a worthwhile exercise in training. is it worth pursuing? i promise you i'm much more fixated on how nevada does against sister jean this afternoon.

rchung, if i understand him correctly, thinks within the pedal circle is important. i don't know that it is. i agree with you that peak force is pretty easily calculable. it just requires and extra field in the equation. others tho, in this thread are arguing that it's silly to back calculate since force is a direct measure. which it is. just, fat chance you'll get that number any time soon from anybody. tho i'd be happy to be proved wrong.

bear in mind, you don't need to be a device maker to give us either. or any. you can be an app. zwift could do this. trainerroad, GC, fulgaz.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 13:05

Post #71 of 160 (3771 views)

Slowman wrote:

stevej wrote:

Slowman wrote:

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Maybe we are misunderstanding you but you seem to be trying to reverse calculate/engineer the power reading to get torque and force. You are making it way harder than it needs to be. You know Force before you know torque and you torque before you know power. No need to calculate torque and force based off watts. They are inputs to the equation to get watts so they are already known.

okay. i'll bite. if i know force before i know torque, you also must know force too. what is the direct measured force you pedaled, on average, during your last recorded ride?

Based on your previous reply I now understand what you are getting it.

So no I personally do not know Force or torque because it’s not readily available to display on my Garmin. But it could be available with a very simple firmware upgrade to current pm’s.

I will say though that there will be a difference on the “measured” force if you get it directly from the pm vs backwards calculating it for every pm but pedal based pm’s. The measured force is the force at the location of the strain gauges which will a higher value on say a crank based pm compared to backwards calculating the force by using crank length.

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 13:16

Post #72 of 160 (3760 views)

Slowman wrote:

Tom A. wrote:

Slowman wrote:

stevej wrote:

Why would you be interested in torque and not force? Torque isn’t measured. It’s calculated. Force is what’s measured by the strain gauges.

two things. first, i predict that by the time we hit 100 posts no one arguing his thesis is going to remember the point of the exercise. so, for the purposes of the point of the exercise, i don't think it makes any difference. if i choose torque as the metric, and i get a wild hair and decide to move up or down 5mm in crankarm length, which i'm unlikely to do, this means a 3 percent difference. so, for the purposes of the exercise, i'd be cool with either. i would not find it a liability to get one metric over the other. right now i have neither.

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Same is true for force (tangential effective pedal force)...they'd just need the user to enter crank length (to divide the torque by).

In fact, I plotted those QA plots I referred to above (which you still haven't told me what your take-away on them is yet...but, I digress...) using power meter data in GoldenCheetah. The only additional information needed was crank length. WKO has the same function as well.

Let me ask this...are you somewhat fixated on torque because you think you might be able to do something about it based on measurements within a pedal stroke cycle? For many reasons (I'm sure you've heard), that's not really "worthy of pursuit"...

first, i'm not fixated on torque. i'm asking whether riding by a different metric - and either force or torque would work for me - is a worthwhile exercise in training. is it worth pursuing? i promise you i'm much more fixated on how nevada does against sister jean this afternoon.

rchung, if i understand him correctly, thinks within the pedal circle is important. i don't know that it is. i agree with you that peak force is pretty easily calculable. it just requires and extra field in the equation. others tho, in this thread are arguing that it's silly to back calculate since force is a direct measure. which it is. just, fat chance you'll get that number any time soon from anybody. tho i'd be happy to be proved wrong.

bear in mind, you don't need to be a device maker to give us either. or any. you can be an app. zwift could do this. trainerroad, GC, fulgaz.

The only times I've ever been interested in pedal force (or torque) is when looking to see if I'm gearing limited in climbing. Long ago I noticed that if I'm over-geared for a particular climb steepness, then my power drops. Looking at the crank torque plot in the old PT software (this type of information HAS been available for quite some time) showed me that the crank torque (i.e. pedal force) stayed constant and I just dropped cadence...hence the power dropped. In other words, at that effort I was force limited. That told me for that climb I didn't have low enough gears.

Other than that...and I think this may be a big part of what RChung has been trying to display...crank torque, pedal force, cadence ALL vary by quite a bit during riding, so trying to artificially constrain one of those things over the others isn't very fruitful. Your body is basically going to "do what it does" to accomplish the effort. Our brains do a pretty good job of controlling our muscle activation for the given effort level.

http://bikeblather.blogspot.com/

Last edited by: Tom A.: Mar 21, 18 13:19

Re: Calling all Coggans [stevej] [ In reply to ]

Mar 21, 18 13:17

Post #73 of 160 (3759 views)

stevej wrote:

Slowman wrote:

stevej wrote:

Slowman wrote:

second, it's much easier to get torque. if i have power and cadence i have torque. as tom pointed out, it's also pretty easy to get force, but i doubt it's easy to get force around the pedal circle without some significant calculations no device maker's likely to do. so, if we're going to circle jerk this thing and then go back to the NCAA tourney and forget about it, fine, let's debate. but a device (or app) maker could give us torque around the pedal circle by coffee break tomorrow if he wanted. meaning, if this were something worthy of pursuit.

Maybe we are misunderstanding you but you seem to be trying to reverse calculate/engineer the power reading to get torque and force. You are making it way harder than it needs to be. You know Force before you know torque and you torque before you know power. No need to calculate torque and force based off watts. They are inputs to the equation to get watts so they are already known.

okay. i'll bite. if i know force before i know torque, you also must know force too. what is the direct measured force you pedaled, on average, during your last recorded ride?

Based on your previous reply I now understand what you are getting it.

So no I personally do not know Force or torque because it’s not readily available to display on my Garmin. But it could be available with a very simple firmware upgrade to current pm’s.

I will say though that there will be a difference on the “measured” force if you get it directly from the pm vs backwards calculating it for every pm but pedal based pm’s. The measured force is the force at the location of the strain gauges which will a higher value on say a crank based pm compared to backwards calculating the force by using crank length.

just realize that trainerroad doesn't need your PM to make that firmware upgrade. it can tell you tomorrow what your torque is, and it can give you a cadence target at any power that corresponds to holding torque. or it could if it wanted to ;-) of course, so could your PM maker. i just think it's much more likely that trainerroad will do it and then your PM will see the utility of it and then give you that firmware upgrade.

but the whole thing revolves around whether its of value to ride (or train) according to some sort of muscle fiber recruitment, muscle shortening, whatever, metric as opposed to the metrics we have now. this is where i'm way out over my skis.

Dan Empfield
aka Slowman

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 14:02

Post #74 of 160 (3723 views)

Slowman wrote:

by average force are you talking about the averaging of peak force over x number of pedal cycles? or average force throughout the pedal circle? because, if the latter, extracting that is not as as simple as average torque.

average torque is simply power divided by cadence. average force, unless it's a direct measure, is not easy to tweeze out of torque.

The latter. *Average* pedal force is actually easy to get if you have crank length. It's just that when I first starting looking at this stuff across several different riders I didn't always have their crank lengths, so I could easily compare their torque but not their force.

In practice, we don't usually have to worry about cranks changing their length in the middle of a ride (if it does that's a completely different problem) so from a practical point of view, whatever you do with pedal force you can do with crank torque.

There are too many cranks in this thread.

Re: Calling all Coggans [Slowman] [ In reply to ]

Mar 21, 18 14:08

Post #75 of 160 (3715 views)

Slowman wrote:

i'm not fixated on torque. i'm asking whether riding by a different metric - and either force or torque would work for me - is a worthwhile exercise in training. is it worth pursuing?

It depends.

Metabolic and cardiovascular strain (and hence adaptation) will be (primarily) determined by the (temporally-smoothed) power output, regardless of how it is generated.

Neuromuscular demands (and hence adaptations in muscle contractile function) will be (mostly) dictated by the force and speed with which you pedal.

I developed quadrant analysis (QA) about 15 y ago as a way of visualizing the latter demands. QA was inspired, in part, by Robert's interest in torque vs. cadence plots and "power expansion pathways", but explicitly incorporates the physiological knowledge that significant type II motor unit recruitment seems to (initially) occur only at intensities above FTP. (The other motivation for QA was people's complaints that NP didn't seem to fully capture the stress they experienced during severely "on-off" cycling, e.g., a criterium).

Once dual-sided power meters that offered additional information about pedaling dynamics became available, I developed additional analytical tools, i.e., calculation of maximum effective pedal force (MEPF), gross power released (GPR), gross power absorbed (GPA), and kurtotic index (KI), all of which can be found in WKO4. This seems to be a bit of a deeper dive into cycling biomechanics than what motivated your original question, however.

A description of QA can be found in our book, as well as here (note that both the date on the article and the byline are incorrect):

https://www.trainingpeaks.com/blog/quadrant-analysis/

These sources describe the pedaling metrics unique to WKO4:

https://www.trainingpeaks.com/...and-metrics-in-wko4/

https://help.trainingpeaks.com/...ling-metrics-in-WKO4

https://irp-cdn.multiscreensite.com/...daling%20Metrics.pdf

TL, DR answer: specificity, specificity, specificity, specificity, specificity.

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