Pedaling Efficiently

[jollyrogers]

Yes there is that as well Frank, doesn't alter the hard data that power goes up and speed goes down in the straights and pursuiting on the track isn't a constant paced effort hence pursuiters using higher cadences than they would on the road.

Don't feel bad Fergie. IIRC it took several people a lot of posts to convince Frank that what he wrote above was true.

Frank, I didn't realize that you had an engineering degree from Navy. What discipline?

 

[Fday]

On a fixed gear?

Sure, if you are properly trained.

 

[Fday]

Don't feel bad Fergie. IIRC it took several people a lot of posts to convince Frank that what he wrote above was true.

Frank, I didn't realize that you had an engineering degree from Navy. What discipline?

Applied Science, then went to nuclear engineering school.

Ugh, the reason it took a lot of posts to convince me of the above is I didn't realize we were talking only wheel speed vs center of mass speed. Once I understood then the analysis is easy. Center of mass speed will drop on the corners because of the increased rolling resistance (and the reduced power).

 

[jollyrogers]

Applied Science, then went to nuclear engineering school.

I knew the second part. Applied Science didn't exist as a major when I graduated (1989).

 

[swampy1970]

Swampy you "think" there is no difference but there is. Can you say the weather was the same during the ride day on day out, your hydration levels were the same, your diet was the same, alcohol intake was the same, fatigue levels, smog, alien activity levels in you area, tyre pressure, gear selection, RPE, the list was endless were all the same for each ride leaving your Gimmickcrank the only constant?

If you're talking a varience of less than a minute on a ~40 minute climb then there'd be ground for wondering if improvement was made. If it was a one time 'ride of my life' that couldn't be repeated I'd be wondering "hmmm, what else changed for that ride" but if you knock over 5 minutes off after a reduced indoor winter of training and then continually back that up in training then you know something good has happened...

... then back that up with being able to ride up both sides of a gnarly mountain pass in the Sierras faster than the year before but with the added kicker that the previous year it was done after 40 miles of riding (Death Ride) rather than 130 (Alta Alpina Challenge). The faster ride was done in hail wearing thermal gear, where as the previous year was done in nice warm (but not hot) conditions. I was lighter the prior year too by 5lbs.

If anything, the change in job which meant getting up 2 hours earlier (never really did go to bed 2 hours earlier) and a 85 mile round trip commute rather than 10, being more involved in my kids sporting activities etc etc should have meant that things should have gotten worse. Less sleep and more time sat on backside typically isn't good.

 

[jollyrogers]

...I didn't realize we were talking only wheel speed vs center of mass speed. Center of mass speed will drop on the corners because of the increased rolling resistance (and the reduced power).

This part you don't have to explain to me. I don't have an engineering degree (Mathematics actually), but I didn't have any trouble understanding angular versus linear velocity.

 

[fergie]

If you're talking a varience of less than a minute on a ~40 minute climb then there'd be ground for wondering if improvement was made. If it was a one time 'ride of my life' that couldn't be repeated I'd be wondering "hmmm, what else changed for that ride" but if you knock over 5 minutes off after a reduced indoor winter of training and then continually back that up in training then you know something good has happened...

... then back that up with being able to ride up both sides of a gnarly mountain pass in the Sierras faster than the year before but with the added kicker that the previous year it was done after 40 miles of riding (Death Ride) rather than 130 (Alta Alpina Challenge). The faster ride was done in hail wearing thermal gear, where as the previous year was done in nice warm (but not hot) conditions. I was lighter the prior year too by 5lbs.

If anything, the change in job which meant getting up 2 hours earlier (never really did go to bed 2 hours earlier) and a 85 mile round trip commute rather than 10, being more involved in my kids sporting activities etc etc should have meant that things should have gotten worse. Less sleep and more time sat on backside typically isn't good.

Thanks for proving my point that every ride was different for more reasons than just the use of a Gimmickcrank.

 

[Fday]

Because as a coach I don't need to know the details of why it happens, I just know it happens and plan accordingly, it's called knowing the demands of your event.

No, you don't need to know the details of why something happens unless, of course, you want to analyze the pheonomen to see if you can improve on what is being done. The data you have provided suggests to me that your riders are riding at too high a cadence, not that the track demands a high cadence. If they were at the correct cadence they would be able to maintain power through the turns rather than see a dramatic drop in power when the cadence comes up. At least that is one interpretation of the data you have provided.

But you have been arguing for a specific cadence on Slowtwitch and you plan to run a chap at the Hour Record at 60rpm.

I don't argue for a "specific" cadence anyhow. I do argue that for long time-trial like efforts (5 hours as seen in an IM) that people should ride at their most efficient cadence for the position they are in. And, for most people that cadence is probably between 60 and 80.

 

[fergie]

No, you don't need to know the details of why something happens unless, of course, you want to analyze the pheonomen to see if you can improve on what is being done. The data you have provided suggests to me that your riders are riding at too high a cadence, not that the track demands a high cadence. If they were at the correct cadence they would be able to maintain power through the turns rather than see a dramatic drop in power when the cadence comes up. At least that is one interpretation of the data you have provided.

One does see a lower cadence the longer the distance one rides on the track and funny enough as the shift from outdoor tracks with less banked bends to indoor tracks with tighter bends has seen an decrease in the cadence used. This probably also reflects the lack of wind resistance on an indoor track. At Denton Park you really hit the Northerly as one comes into turn 4, ride slower times and use smaller gears.

Most National Track Teams employ a form of Strength Training (SE) or Big Gear World like seated start Kilos on 115" - 120" gears yet still chose to ride (and ride faster) on a 94-98" gear in the Kilo event. I would expect the use of a higher gear and lower cadence makes the transition from the bends to the straights more of a challenge hence why you still see a relatively high cadence in pursuits (110-120rpm) and event the Hour Record (around 100-105rpm). It's very common to hear a pursuiter blame too big a gear and rare to hear anyone claim the gear was too small.

 

[swampy1970]

Thanks for proving my point that every ride was different for more reasons than just the use of a Gimmickcrank.

It pains you to think that if I train for a couple of years using very similar training and roughly get 'x' amount of improvement each year and then I do something different and get get triple that improvement that it can't be down to the single piece of equipment that you loathe.

Just for you big guy:

As much as I dig the new Cannondale Hi-Mod and those seemingly helium filled Hollowgram SL cranks, these puppies are probably the biggest reason why I'm putting out more power now than I was back when I was racing, despite not being able to devote nearly every minute of every day to bike related activities, not having constant access to a really good coach to oversee my training or even just plain simple not even racing anymore.

... and yes, I don't ride with them at 220mm - I just needed to set them like that so I could get the Dura Ace pedals off.

 

[roadhouse]

Ummm Roadie Check your Meds, Phinney and Pendalton have never been to NZ, Pendalton's parents have.

whatever, fattie.

 

[fergie]

Quiet Roadie Adults Talking.

Doesn't pain me at all, Swampy, rather amusing the ways you justify pi**ing a Grand down the drain. You have no real evidence that Gimmickcranks did anything. Just another anecdote.

 

[Alex Simmons]

Hey Fergie, I thought I would bring this back up because I would like to know if you can explain what is going on here for the "masses"(as if anyone would classify the few still viewing this thread as "masses") who may not understand or who may think you just mistyped.

In general, one would expect higher speed to require higher power yet above your write: "Speed goes up in the bends and power goes down and vice versa on the straights." Anyhow, just thought I would find out if you could explain why this is so without violating the laws of thermodynamics.

Thanks for sticking around.

Actually it has to happen in order to be consistent with the laws of thermodynamics. And anyone who's ridden the track or inspected power meter data from track riders would know this in any case.

The speed measured at the wheels goes up when you transition from straights to bends for two reasons:

1. In the bends the wheels travel a greater arc than the centre of mass of rider, while both are traveling at the same rotational speed. This creates an increase in the pedal speed (fixed gear) which sometimes take a little practice to anticipate and keep the power down. In the straights the wheels and COM travel the same infinitely sized arc (i.e. a straight line).

2. the COM actually lowers when entering the turn (you lean over) and that lowering of gravitational potential energy is converted to an increase in kinetic energy (speed) of the COM. In this way the laws of thermodynamics hold. This adds to the effect described in 1, impacting on the fixed gear cadence in a way that naturally leads to a drop in power output.

The reverse applies when transitioning from turns to the straights.

This is why the speed line (blue) from riding the track looks pseudo-sinusoidal, such as in the example below of 10 laps taken from the track. The power line (yellow), while not a perfect mirror of the speed line, pretty much shows the opposite.

If you look - as the speed drops (enters the straight), the power goes up, then falls again in the bends. Of course sometimes the rider anticipates and tries to keep power going into the bends but it doesn't always happen and the constant fluctuation is sort of natural.

This effect is amplified the faster you go, since the higher the speed the greater the lean in the bends and the greater the change in potential energy of COM.

You can read more about the effect of lean in the bends at analyticcycling.com.

and with 5-sec averaging to sooth the constant changes a little:

Of course it gets quite fun when performing forward integration to predict speed from power on the track and accounting for the variance in speed of COM on air resistance as well as different rolling resistance between straights and bends.

 

[Fday]

If you look - as the speed drops (enters the straight), the power goes up, then falls again in the bends. Of course sometimes the rider anticipates and tries to keep power going into the bends but it doesn't always happen and the constant fluctuation is sort of natural.

To me, looking at those graphs, I see almost no correlation. There may be a tendency for this but what is going on is all over the place. Perhaps this is a fatique issue, I don't know but if a mathematician were to compare these graphs and look at the correlation I suspect it wouldn't be anywhere near 90%.

I can understand why power might drop in the curves because of the increased cadence but I could also see a reason why the rider might want to develop the ability to have the highest power in the curves, where the wind resistance is less.

This effect is amplified the faster you go, since the higher the speed the greater the lean in the bends and the greater the change in potential energy of COM.

Actually, I think the effect is less the faster you go. One does lean over more but the increase in lean is incremental. I did some quick calculations and I felt the maximum energy benefit a 70 kg rider might see from this effect might be about 200 joules. The increase in lean from going 20 mph to 30 mph might increase the energy benefit effect 10-20 joules. But, because of the increased speed and the fact that kinetic energy is calculated on the basis of velocity squared, the faster one goes the actual absolute speed increase should become less.

You can read more about the effect of lean in the bends at analyticcycling.com.

and with 5-sec averaging to sooth the constant changes a little:

Of course it gets quite fun when performing forward integration to predict speed from power on the track and accounting for the variance in speed of COM on air resistance as well as different rolling resistance between straights and bends.

What I am taking from this is riding a track, while it seems straightforward, is just as complicated to analyze as riding out on the road where wind and road surface variations come into play. Plus the wind is completely different. On the road, wind shear says wind will be greater the further one is off the ground, where the greatest frontal area is. On the track, wind is reduced the further one is from the track, at least in the curves.

Anyhow, I now understand why it is a national track coach told us his hope with getting his athletes on the PC's is it would help them to even out the power distribution around the track. I didn't understand what the issue was. Now, I think, I do. I will have to ask him how this went.

 

[BikingBrian]

-snip-
As much as I dig the new Cannondale Hi-Mod and those seemingly helium filled Hollowgram SL cranks, these puppies are probably the biggest reason why I'm putting out more power now than I was back when I was racing, despite not being able to devote nearly every minute of every day to bike related activities, not having constant access to a really good coach to oversee my training or even just plain simple not even racing anymore.-snip-.

SO do you race with them? Or only use them during training? If so, what is the reason?

 

[Alex Simmons]

To me, looking at those graphs, I see almost no correlation.

You need to look again.

but I could also see a reason why the rider might want to develop the ability to have the highest power in the curves, where the wind resistance is less.

Well I can understnad wanting to even out the application of power, however I don't see how wind resistance reduces in the turns when the centre of mass is traveling faster through the air than when in the straights, it would go up, not down.

There is one potential factor to consider and that is the variability in the yaw angle of "wind".

Actually, I think the effect is less the faster you go. One does lean over more but the increase in lean is incremental.

The faster you can go, the faster you can go. Did you look at the analytic cycling item on the effect of lean in the banking?

What I am taking from this is riding a track, while it seems straightforward, is just as complicated to analyze as riding out on the road where wind and road surface variations come into play.

Well it's no more complicated - the physics is the same - just different elements come into play. Nevertheless, because the conditions are more benign, one can analyse things with greater precision, or pick out effects that would be lost in the noise outdoors.

As an example, I can see such tiny effects such as tyres warming up, a rider entering the opposite side of the track.

Anyhow, I now understand why it is a national track coach told us his hope with getting his athletes on the PC's is it would help them to even out the power distribution around the track. I didn't understand what the issue was. Now, I think, I do. I will have to ask him how this went.

I don't understand how this would help. One just needs to ride the track and do enough laps and inspect their power meter data.

 

[fergie]

Does beg the question of the role of cadence. In an hour record ride does it matter if the rider is doing 130rpm in the bends and 125rpm in the straights or 60/65. All I have to go on is empirical evidence that far more pursuiters blow big time on bigger gears than those using smaller gears. In Six Day racing on 160m tracks they use tiny gears for the Madison events.

What I don't see is any value in using Gimmickcranks to try and smooth out the bends. The effect of the bankings on power and speed is very clear. I gave an example of dropping to 320watts in the bends and peaking at 530watts in the straights. If your suggestion that cadence is irrelevant then how do you propose that a rider could smooth out the bends? You may want to ask your imaginary National Track Cycling Coach that one.

Alex is right in that the faster you go the greater the effect. Just checked some of my (sadly pathetic) data from the track and the variances seen from the section I posted from a former World Champ that varies as much as 250watts every half lap where I only vary around 150watts each half lap.

 

[wahaneebelly]

Generally speaking,I'm just over 5'10, 34" inseam. I've ridden 170, then 172.5 and am now riding 175. Couldn't tell the difference between them. I think the farther back on the pedal the foot is the more stress will be put on the knee. Conversely, the further forward on the pedal the foot is less stress will be put on the knee.

 

[swampy1970]

Quiet Roadie Adults Talking.

Doesn't pain me at all, Swampy, rather amusing the ways you justify pi**ing a Grand down the drain. You have no real evidence that Gimmickcranks did anything. Just another anecdote.

If I got faster then it's not pissing away a grand. If being forced to use my hip flexors was one of the main reasons why my back pain ain't as bad as it was then it aint pissing away a grand.

But it would seem, from your rationale, that collecting my data and applying it to me isn't the way to to go, just because someone else didn't have the same results as I. Lets get all generic and apply someone elses data to my own situation. I'm so glad I had the coach I did when I was racing and not you.

Personally, I don't care that a study on good first cat road guys showed that mashing was great. I'd care a little more if data from guys like an on form Boardman (when he smashed the best for 5 minutes in the GP des Nations), Indurain (when he took over 4 minutes out of LeMond and Bugno) was available. Likewise, I also don't care that guys like Evans, Bettini, Ricco etc etc used Powercranks in training.

I'll continue doing what I'm doing and changing a variable every couple of months and track progress.

Pissing away a grand on cranks would be buying a set of those Stronglight carbon jobbies... can't send those back for a full refund if you spot no difference in the first 3 months.

Pissing away two grand would be you having two disk wheels on a track bike.

Brian,

To race on them I'd have to race. I won't be racing on the PC's because they don't come with a BB30 bottom bracket and I don't fancy being forced to lift the darned crank up for 8+ hours in the one race that I will be doing this year plus I don't see any difference in the power if I switch to standard cranks in a short period of time. Plus the adjustable ones that I have weigh more than the frame, forks and cranks on the Cannondale. Great for training, racing... maybe on the flat. In an event with 29,000ft of climbing - I'd have to spend 5+ hours in the saddle in similar hills to the event for figure that one out.

 

[Fday]

You need to look again.

Well I can understnad wanting to even out the application of power, however I don't see how wind resistance reduces in the turns when the centre of mass is traveling faster through the air than when in the straights, it would go up, not down.

I guess it is possible but I don't see the CM traveling faster through most of the turn and the CM is not where most of the wind resistance is found. On a bike in the aero position the CM is probably somewhere around the hips or slightly below. The increase in speed from the potential energy contribution is soon lost as the wind resistance will quickly slow the bike back down unless the power goes up to maintain this new speed which has been shown here to not occur - in fact, the claim is the power drops considerably. So, the CM speed increase from the PE contribution has to be very transient at racing speed. But, the conservation of momentum issue is constant through the entire turn. So, while wheel speed is increased the speed of the head, shoulders and abdomen will be slower. The head, shoulders and abdomen are the major contributors to the drag.

It seems to me this is mostly theoretical and the advantage, if any, would be small and owuld be difficult to achieve. A constant application of power is probably a better and more achievable goal for the rider to aim for.

There is one potential factor to consider and that is the variability in the yaw angle of "wind".

The faster you can go, the faster you can go. Did you look at the analytic cycling item on the effect of lean in the banking?

Well it's no more complicated - the physics is the same - just different elements come into play. Nevertheless, because the conditions are more benign, one can analyse things with greater precision, or pick out effects that would be lost in the noise outdoors.

I don't see the analysis as easier or more precise because the wind shear is backwards, at least on the turns. Actual wind gets faster the further off the ground one is So the wind is greater at head shoulder height than at wheel height when outside. Wind tunnel wind tends to be the same speed at the ground and at the head. Neither of these conditions apply during the turns. Where does one get the data to come up with a correct drag number that is "more precise". What is the correct wind speed to use? I don't see it as being more precise.

The other problem I see is I think the data is not precise enough to understand what is really going on. The change in speed when the rider banks into the corner and banks out should essentially be instantaneous (occurring within a couple of meters or so) then the dynamic remains constant with the different wind shear and a different rolling resistance (from the increased g forces) until out of the turn where everything changes quickly again. The graphs I see do not reflect this expected rapid change but show a smoothing as pm's are not designed to collect and display this degree of accuracy in either speed or power.

As an example, I can see such tiny effects such as tyres warming up, a rider entering the opposite side of the track.

I don't understand how this would help. One just needs to ride the track and do enough laps and inspect their power meter data.

Well, I can understand how one can see tires warming up in the power data but could you show me how you can see "a rider entering the opposite side of the track". How is that reflected in the power data?

And, people here have been talking about using the PM data to help with racing but all we are getting here from people like Fergie is "it happens". Well, what good does that do the rider if he doesn't try to do something better next time out once he understands what is going on unless he determines that it doesn't make a difference.