Single Speed Training

Strith

Alex_Simmons/RST wrote:

If you are averaging part of the pedal stroke (which part I'm not sure), fine but you can't just ignore the whole. By examining the whole we can see the average force demand and we already know the typical relationship between peak and average.

The fact that we pedal in a more piston like manner and have a pseudo-sinusoidal torque pattern still doesn't make us force (strength) limited for sustainable power outputs. It's a red herring.

I wrote a long reply and then the server died so meh. But basically this was the point I was trying to get across.....badly.

twotyred

I know that letting-go of a long-held misconception can sometimes be difficult - but it might be better at this stage just to accept that you were wrong, and move on

I think you need to keep up. The discussion has has moved on somewhat and the section you quoted is around how we choose to measure the amount of max force required to turn the pedals at a certain cadence to generate a certain power. The methods that Alex and I chose to use are approximations we're just disagreeing about which has greater validity. This has moved on from an argument about whether we're strength limited as cyclists which I'm prepared to accept, on a strict definition of strength as the max force you can exert with your legs, is not a limiting factor except in certain sprinting situations.

I also accept given the above definition of strength its a misnomer to call training yourself to be more effective at turning slower cadences with higher force strength training but its a commonly used term for that type of training session.

imposter2.0

twotyred wrote:

I think you need to keep up. .

ironic - seeing as you are the one being corrected here..

twotyred wrote:

The methods that Alex and I chose to use are approximations we're just disagreeing about which has greater validity.

I believe Alex does this professionally - and I suspect you don't actually measure anything at all. Why is there a disagreement?

twotyred

One could just as easily put an electric motor drive on the crank spindle with perfectly even force output at all rotational angles at same power and the bike would go and/or accelerate at the same rate as if it had a bike rider applying forces in a typical pseudo-sinusoidal manner.

Of course it would but only if the pseudo-sinusoudal force input by the rider averaged out to the same force being applied continuously by the motor.

Please answer this. For a rider with an AEPF of 500N what would you estimate the force is at the high point of the sinusoudal distribution? It has to be greater than 500N. That's the point I'm making. To output an average of 500N unless your legs are electic motors then at some point you will generate a force greater than 500N. Now the difference between peak and average force in normal riding is insignificant and probably not worth spending more time on. Only place it might be significant would be sprinting if you were force limited.

Well you were not estimating peak force either in that example you quoted from analyticcycling.com, so to be honest I'm not sure what you were estimating.

5 posts later I worked back from power manually (see below). Only difference from your method as I pointed out earlier is that I made a rough assumption that force was only applied for 180 degrees of the crank rotation which I admit is not sinusoidal and an over estimate but doesn't change the fact that average force is an underestimate.

"We could work it out another way. Let's assume Greipel has a power output of 1600 watts when sprinting. That's a torque of 152 Nm. That's roughly 873 N. However let's assume that's only applied through half a pedal revolution (2 legs x 90 degrees for simplicity) that's 1746 N or the equivalent of 177 kg."

I believe Alex does this professionally - and I suspect you don't actually measure anything at all. Why is there a disagreement?

Actually I'm a scientist and measure lots of things and make a good living from it. Why shouldn't I disagree with someone just because they are paid money to do something? However I will admit that the point we're disagreeing about is not significant in the real world so probably not worth spending more time and energy over although it has been fun.

Strith

twotyred wrote:

5 posts later I worked back from power manually (see below). Only difference from your method as I pointed out earlier is that I made a rough assumption that force was only applied for 180 degrees of the crank rotation which I admit is not sinusoidal and an over estimate but doesn't change the fact that average force is an underestimate.

"We could work it out another way. Let's assume Greipel has a power output of 1600 watts when sprinting. That's a torque of 152 Nm. That's roughly 873 N. However let's assume that's only applied through half a pedal revolution (2 legs x 90 degrees for simplicity) that's 1746 N or the equivalent of 177 kg."

But in your example you only need to increase the riders cadence to 130 and and the equivelat force comes down to about 130kg for the given power (which has been suggested to be high for the road sprint example). And thats still assuming this 90 degree cut off which isn't correct as Alex has already alluded to.

Alex has also said that the pedal forces follow a more sinousoidal pattern, so as a scientist I'm sure you're aware that avearage and root mean square values for sinousoids are given as Pk x 0.637 and Pk x 0.707 respectivley. Woud you not agree that if you want to make assumptions and try and calculate back to peak values that using one of those methods would be better?

So taking your 500N gives 78kg peak force at best. And you can still get your 1600W at an optimistic peak 100kg force.

Thas all ignoring Alex's experience wich probably suggests less again.

twotyred

Woud you not agree that if you want to make assumptions and try and calculate back to peak values that using one of those methods would be better?

Thanks that's not something I keep in my head or could be bothered to look up but I never said my method was anything other than rough (although my assumption of 0.5 isn't far away from your 0.637). My point has always been that if you are going to calculate the force a rider needs to achieve a particular power output at a particular speed then it should be peak (whatever that peak is) and not average.

Agreed, with your figure around 80 kg would the equivalent for an average force of 500N

But back to a cyclist generating 1600watts at 100rpm gives us an average force of 873N and a peak of 1370N

Converting that 1370N to kg gives us 140kg. That's getting on for twice my bodyweight- 60% higher than the 88kg average equivalent. Well I guess I could lift something as heavy as myself and go a few steps with it but I think before I did so I might want to get a few squats done in the gym.

Yes increasing rpm decreases the required force so at 120 rpm peak force for the same power is reduced to 1142N or 116kg and going up to 130rpm reduces it to a more managable 107kg.

Now I just have to figure out how to pedal at 130 rpm whilst standing on the pedals :shock:

Alex_Simmons/RST

twotyred wrote:

My point has always been that if you are going to calculate the force a rider needs to achieve a particular power output at a particular speed then it should be peak (whatever that peak is) and not average.

OK, well I disagree on that point. Knowing the peak force is interesting for sure, but it won't tell you how much power you will/can produce.

Well let me rephrase that - it can tell you the power for the 50-milliseconds that the peak occurs, but that's a pretty unhelpful bit of information, since:
- the power numbers that matters are the result of the sum of the torque and rotational velocity for the entire pedal stroke (or strokes). You simply can't ignore the entire pedal stroke.

- the shortest cycling event I can think of is the 200m flying TT, which is a maximal effort for around 15+ seconds, after a sub-maximal lead up, and the start rider for a team sprint, which is a maximal effort for ~18 seconds at world elite level.

- peak force in such events is not always correlated with actual performance. Force has to be applied at speed, and it is the relationship between force and speed that matters for neuromuscular (i.e. very short duration) power.

- peak power (per pedal stroke) in a maximal sprint like effort (rolling or standing start) does not occur when peak force does. Peak power occurs while peak force is rapidly declining.

twotyred

We're starting to go round in circles here.

Peak force is a barrier that has to be overcome to allow a rider to turn the pedals with a particular average force which will generate a particular power output for a given rpm (notice I'm not ignoring average force). In that sense it is important. Average force allows you to calculate/generate power, peak force gives you the instantaneous force you have to generate in a small part of the pedal stroke to allow you to turn the pedals 360 degrees to generate that average force number.

Power depends on force x speed so I agree peak force will not always correlate with performance because power also depends on how fast the rider turn the pedals

Alex_Simmons/RST

twotyred wrote:

Peak force is a barrier that has to be overcome

You seem to be fixated on this concept that we are force limited. That somehow peak force during a pedal stroke is a barrier to improving endurance cycling performance.

Let me say this once more:
The peak forces experienced/produced in endurance cycling are significantly sub-maximal and are not our limiter. Our limiter is a metabolic/biochemical in nature, not in force production.

Perhaps a really obvious personal example might give you some insight:
After a trans-tibial leg amputation in 2007, my peak force generation ability took a big nosedive, as you'd expect with half a leg missing. Yet I managed to return to competitive cycling with a threshold power higher than I had prior to amputation. Fortunately this was possible since we are not force limited.

My peak sprint power however did take a hit. It's now only about 320W more than Chris Boardman's was at his peak. Fortunately for Chris, he could sustain ~6.4W/kg at threshold, wear TdF yellow after a prologue win and set a world hour record despite having a peak force capability less than the average club rider.

twotyred

You seem to be fixated on this concept that we are force limited. That somehow peak force during a pedal stroke is a barrier to improving endurance cycling performance.

You continue to misunderstand. Many posts above I said "For general road cycling I agree that the pedal forces required for maintaining 200-300 watts are nothing special and maybe your granny could generate the required force"

Doesn't sound like I'm fixated on being force limited and pretty much agrees with you. In fact I'll add that the pedal forces required for endurance cycling whether peak or average are nothing special.

Peak force is a barrier that must be overcome in order to generate an average force. Peak force as we've seen above may be significantly higher than average force but however at endurance efforts its still not a big barrier and doesn't limit us.

My point is simply that there are times, notably in sprint situations, when average force may not give the whole picture and that peak force should be considered as well.

To me your example of how losing a lot of your peak force resulting in reduced peak sprint power implies that you were strength/force limited in sprints.

imposter2.0

twotyred wrote:

My point is simply that there are times, notably in sprint situations, when average force may not give the whole picture and that peak force should be considered as well.

I don't think anyone is arguing that higher peak forces would not lead to higher averages, but when would these times be, when average force would not give the whole picture ??

twotyred wrote:

To me your example of how losing a lot of your peak force resulting in reduced peak sprint power implies that you were strength/force limited in sprints.

after a lower leg amputation - does that suprise you ?

markos1963

Froomes Edgar wrote:

I wonder if your knowledge of wheelbuilding is as poor as your knowledge of training?

And your qualification in cycle training is?

Matchstick Man

markos1963 wrote:

Froomes Edgar wrote:

I wonder if your knowledge of wheelbuilding is as poor as your knowledge of training?

And your qualification in cycle training is?

Do you need qualifications if you're right?

iPete

wtf is this babble, has no one point out where he is going wrong!? single speed, flip that flop over to fixed.

it is scientifically proven by the boffs at lucozade and peer reviewed by the team that pick stars for the Nike sponsorship program that fixie creates power awesome™.

power awesome™ = rider strength before + 200kg squat at 3x10 reps x gear inches x 0.25 Mark Cavendish

Strith

twotyred wrote:

Peak force is a barrier that must be overcome in order to generate an average force. Peak force as we've seen above may be significantly higher than average force but however at endurance efforts its still not a big barrier and doesn't limit us.

But you're still going on the approxiamtion made earlier. Even using the example of a sinusoid I gave you would still in my opinion overestimate force by a long way.

Look at the wattbike power distibutuion data in this link. See for the beginner example, figure of 8. It's sinusoid like, but you'd still say a sinusoid would be overestimating.

Now look the sprinter example 1500W. Look at the shape, it's nowhere near a sinusoid. Anyone who works with numbers will look at that distributon and see straight away that peak values are nowhere near what you would get if you modelled it as a sinusoid. It's a massive overestimation.

This link here:
http://www.cyclosport.org/09-Feb-2011/t ... tbike.html

twotyred

after a lower leg amputation - does that suprise you ?

No does it surprise you? What's your point?

Does shows that max strength is a factor is generating sprint power.

From Alex's post "my peak force generation ability took a big nosedive" and "My peak sprint power however did take a hit" He's connected the two not me.

twotyred

Anyone who works with numbers will look at that distributon and see straight away that peak values are nowhere near what you would get if you modelled it as a sinusoid. It's a massive overestimation

Good link. Calculated average force for that 1488 watts power at 144 rpm would be 563N. Looking at the distribution it looks like at the outer perimeter of the data the min force is 440N and the max is touching 880N so actual average could be a bit higher. Shall we say 600N? That gives us average force = max force x 0.69 Pretty close to your sinusoidal figure of 0.637. Let's be generous and say the average is 700N that would give 0.79. So yes a sinusoidal distribution its an overestimation but whether its massive or not I guess depends on your idea of massive. Shame we don't have an actual average force figure from the Wattbike.

imposter2.0

twotyred wrote:

after a lower leg amputation - does that suprise you ?

No does it surprise you? What's your point?

Does shows that max strength is a factor is generating sprint power.

Round in circles again. Nobody has ever said that 'max strength' is not a factor in sprint power, although you are only ever likely to use 'maximal' strength from a standing start. Anyway, it's why most track sprinters do weights, as was mentioned earlier. It has nothing to do with sustainable power though.

twotyred wrote:

From Alex's post "my peak force generation ability took a big nosedive" and "My peak sprint power however did take a hit" He's connected the two not me.

Indeed. He connected the two in order to make the point that his sustainable power on the bike actually increased, despite having had part of a limb removed. If you don't have two 'complete' legs (with apologies to Alex), then a drop in force generation does not seem unreasonable really. You seem to have some sort of selective reading ability.

twotyred

He connected the two in order to make the point that his sustainable power on the bike actually increased, despite having had part of a limb removed

Amazingly I managed to understand that as my post at the top of the page clearly shows.

In reply to his last post I merely pointed out that his experience of sprint power dropping off suggested he is force limited in sprinting despite still being capable of sprinting better than Chris Boardman. No idea why you had to make a snide comment about that.

I'm impressed at your determination to deliberately either ignore or misinterpret my previous posts in order find something on which to disagree with me however I'm not going to engage with you any further.

imposter2.0

twotyred wrote:

In reply to his last post I merely pointed out that his experience of sprint power dropping off suggested he is force limited in sprinting despite still being capable of sprinting better than Chris Boardman. No idea why you had to make a snide comment about that.

Because (and apologies for second-guessing here) I suspect that Alex already realises he is 'force limited' in that respect. Not sure why you felt the need to state the bleedin obvious.

Alex should go and talk to these fellas here - a lot of them aren't quite getting it either...

Strith

twotyred wrote:

Good link. Calculated average force for that 1488 watts power at 144 rpm would be 563N. Looking at the distribution it looks like at the outer perimeter of the data the min force is 440N and the max is touching 880N so actual average could be a bit higher. Shall we say 600N? That gives us average force = max force x 0.69 Pretty close to your sinusoidal figure of 0.637. Let's be generous and say the average is 700N that would give 0.79. So yes a sinusoidal distribution its an overestimation but whether its massive or not I guess depends on your idea of massive. Shame we don't have an actual average force figure from the Wattbike.

Either way, that data suggests trying to model it and calculate peak forces is pretty pointless because as you can see technique varies too much between riders. There is a big difference between the analitycalcycling estimtion of 170kg and this 88kg from actual data (for a trackie granted).

From that data alone I would conclude that as stated previously, for road cycling we are not force limited, even when sprinting. Rather I would say we a limited by a combination of lack of aerobic capacity and good technique.

If you still think road sprinters are force limited then thats your call, but I don't see it that way.

Alex_Simmons/RST

Examples of the varying torque patterns amongst state and national level cyclists in a TT:



Data from Coyle et al study. With exception of one rider, the average power output of these riders ranged from 300-376W.

Also, the torque patterns were maintained when riders were required to ride at same power (162W left) and cadence (90 rpm).

Strith

Thanks Alex, I will have a look at some of those guys publications.