Pedaling Efficiently

[Fday]

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.

Does cadence make a difference? Well, go look at any scientific study that looks at power vs cadence. Find one where the rider's sustainable power doesn't drop off moving from 125 to 130 cadence. Once one is above the most efficient cadence any increase in cadence would be expected to result in a drop in sustainable power.

And, the speed variation is the same regardless of cadence. So your 4% variation in cadence at 125 rpm would result in only a cadence change from 60 to 62.5 at the lower cadence. I doubt many who have trained themselves to ride that cadence would notice that difference where I suspect that many would notice a change from 125 to 130.

Wasn't it a few years back that Anna Mears set a new world record when the mechanic put the "wrong" gearing on the bike and she rode a bigger gear unknowingly?

I think smoothing out the power in the bends would be relatively easy. Just increase the gear size and lower the cadence. The problem that the track rider has to confront in trying to do this is they also have to concern themselves with getting up to speed quickly and big gears work against that. So, they have to compromise between rapid acceleration to top speed and power and a lower top speed and more power variation. The longer the race though and this getting up to speed quickly becomes less of an issue and that is where bigger gears should show their advantage.

Oh, and could you point out to me where I have ever claimed that cadence is "irrelevant"?

 

[Fday]

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

The "applied science" major was called the "nuclear science" major until I was a senior when it was determined by Rickover that Rickover had to be in charge of everything in the Navy with the name "nuclear" in it. since he had no absolute control over the major or the Academy the name was changed.

 

[Fday]

YDid you look at the analytic cycling item on the effect of lean in the banking?

Well, I finally went to anallytic cycling and read their Velodrome analysis. Interesting but there are some issues that really makes their analysis not apply to this discussion.

first, they are mostly focused on the flying 200 meters. The path they are utilizing is more than just banking but also utilizes the height of the track to advantage also. One example:

Then, the power profile is the profile of someone sprinting in a straight sprint, not showing the power variations actually seen, as has been pointed out repeatedly here. Fergie mentions variations between above 500 watts on the straights and 350 watts on the curves. Nothing like what they are using. It would be interesting to see if the model showed an advantage to a steady power application. Or, at what steady power would there be an advantage compared to the average as is currently done.

Their speed profile is similar to what I described as being the theoretical, with a rapid increase or decrease at the beginning and end of the turn and a decrease in velocity through the turn. The speed they are always talking about is CM speed, not wheel speed (the shape should be similar only the amount of change would be greater using wheel speed). They see performance improvement because they talk about a shorter course where the speeds in the graphs you have presented are talking wheel speed and it is obvious the "real data" has a lot of noise in it as it doesn't reflect the theoretical stair step look but looks more sinsusoidal on average.

compared to "actual"

So, it seems to me that the analytic cycling model is deficient in two major aspects regarding this discussion. It is not a steady state model applicable to pursuit analysis and it does not take into account the actual power variations seen by the usual rider. Further, they say that taller riders would see an aerodynamic disadvantage. This might apply on an outdoor velodrome but I think they got it backwards on an indoor velodrome.

 

[fergie]

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.

But how, everyone trains big gears for strength blocks but select smaller gears and higher cadences for racing. If bigger gears were faster you would expect people to use them in competition. Why reinvent the wheel. Accept the situation and train for it. The British Track Cycling team's sprint programmes greatest expense is buying track time so the riders can train specifically for the track. Otherwise you could just put some markers on the road and just do sprints uphill downhill, tailwind, headwind (BTW the current US record holder for 200m and 1000m did train like this because he lived 600miles from a track). A pursuiter would just do 4 min efforts on an erg but fortunately our powermeters tell us these are not the demands of the event and we now know how we need to prepare for track racing.

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.

That is because my Powertap records every 1.3sec and the SRM every 1 sec. Most teams now use the SRM scientific model that records every .1sec. The data is pretty clear. But the range we see in all the data is also pretty self explanatory.
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.

Yes and I have data to show it happens rather than a Swampy like "I think" it happens. My riders do it better, they go faster next time, not because they smooth the bends out (there is a technique that can be used on some tracks to achieve a better transition in) but because they prepare for the demands of the event and I have the data to show that as well

 

[RChung]

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?

If you can understand how warming tires affect the data you ought to understand this one, too. Both look like a change in the power-speed relationship.

 

[BikingBrian]

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. -snipped portion about weight of cranks-

So...the rationale behind powercranks (if I'm understanding this correctly) is that you're forced to change your pedalling style in training, and after some time you can apply that "improved" style to regular cranks, right?

If that is the case, why would you ever ride standard cranks (apart from the weight disadvantage)? IOW, if there was a clearly discernable change in your power application, you should be able to do that regardless of what cranks you are using...

 

[Fday]

If you can understand how warming tires affect the data you ought to understand this one, too. Both look like a change in the power-speed relationship.

How does a rider entering the other side of the track become reflected in the power-speed relationship?

 

[swampy1970]

So...the rationale behind powercranks (if I'm understanding this correctly) is that you're forced to change your pedalling style in training, and after some time you can apply that "improved" style to regular cranks, right?

If that is the case, why would you ever ride standard cranks (apart from the weight disadvantage)? IOW, if there was a clearly discernable change in your power application, you should be able to do that regardless of what cranks you are using...

you did understand the rational correctly. They force you to effectively unweight the rising pedal. Once I'd used them for a few months and got to the point when i was so relaxed, it was an almost an unconcious effort, then my pedalling changed pretty drastically.

After getting lazy and discovering beer again at the end of last year, I didn't forget how to pedal with them - it just took a little longer to get the psoas muscles comfortable with sustained effort again.

Why don't I use them all the time? Weight for one - the adjustable version with lockout must weigh a good 5 or 6 lbs for the pair. Endurance rides is another - some rides that I like to do, like the Alta Alpina, are 14+ hours in the high mountains. I've never ridden more than 4 hours on the pc's and while I didn't feel like they didn't cause any extra fatigue I don't want to try that extra 10 hours finding out. Maybe an early season flattish 'double' or an interesting century would be a good test.

I'd actually wouldn't mind testing them on the old time trial bike (see my avatar).

Once the novelty of the new carbon bike (happy 40th birthday to me) has worn off and I get the position dialed (and get another pair of pedals!) i'll be back training on the other bike with PCs, especially when the hard training begins in July.

 

[RChung]

How does a rider entering the other side of the track become reflected in the power-speed relationship?

Go stand on the sidewalk of a street with a lot of traffic. You can feel the air as the cars pass. Same thing happens on a velodrome. Two riders on the track, even if they're on opposite sides, stir the air more than one rider.

 

[Fday]

Go stand on the sidewalk of a street with a lot of traffic. You can feel the air as the cars pass. Same thing happens on a velodrome. Two riders on the track, even if they're on opposite sides, stir the air more than one rider.

A lot of traffic is not "another rider entering the track on the other side" last I looked. Could you show me how that is reflected in the readout/numbers that it can be seen? On a 250 meter track you are telling me there is a measurable drafting effect 125 m behind someone else that can be picked out of all that noise? How much faster or slower does a rider go when racing pursuit, with another rider on the track than when riding alone in training? List me as a disbeliever until I see some substantial evidence.

 

[RChung]

List me as a disbeliever until I see some substantial evidence.

Hmmm. Okay, well, since I'm not sure you'd understand the evidence I guess I can live with that.

 

[swampy1970]

Yes and I have data to show it happens rather than a Swampy like "I think" it happens. My riders do it better, they go faster next time, not because they smooth the bends out (there is a technique that can be used on some tracks to achieve a better transition in) but because they prepare for the demands of the event and I have the data to show that as well

Hey bud, you're not the only one collecting data...

... and just for the record, I have power data (Kingcycle and lab data) going back to the mid 90s. Could throw in a whole telephone directories worth of heart rate graphs and lactate curves too while I'm at it from the mid 90s as well.

Fancy some Q Ring data on positions 1 and 3 and 3 Vs round chainrings? (position 5 felt too weird)... and while you're touting the merits of 165's like you were many months ago, I'll be doing some tests at the end of the year with different crank lengths (adjustable powercranks gotta love 'em) over a couple of weekends probably at the end of Sept (it's not 1,000,000F during the day then) - or the end of July if I get to my target weight by then. 4 days of climbing and rouleuring up the valley roads just too see if (a) the data that I got a couple of years ago re:185 Vs 175s still stands on the hills and (b) were gains I got in 1996 in time trials due to a change in crank length (speed went up when cranks were changed) or was something else at play?

Figuring out tests for those should be interesting. Seeing if riding 185s after losing weight is easier than it was when I was over 190lbs would be interesting too. 220mm cranks. That'd be worth trying just for the hell of it...

I figure that if a weekend or two of testing can produce some results above and beyond what I'd gain through a few easy weekends then it'd be something to look forward too.

I could throw in a bunch of tire temp, tire pressure, shock setting, anti-roll bar setting, estimated spring rate (from known spring information and ride height setting) and intake temp data from when I raced cars here in the US - SCCA regional champ in my class - if you fancy changing topics but still talking data. I would have had EGT data too but the class I raced in didn't allow modifcation of exhaust manifolds and downpipes.

Got Data? Bite me.

 

[fergie]

Hey bud, you're not the only one collecting data...

Difference is I know what the data tells me and what it doesn't tell me. No where does your data isolate the Gimmickcranks and nowhere does it tell you if you would have done better on normal cranks.

Keep dreaming.

 

[Fday]

Hmmm. Okay, well, since I'm not sure you'd understand the evidence I guess I can live with that.

One thing for sure, it is not possible to understand evidence that is not presented.

 

[Enriss]

One thing for sure, it is not possible to understand evidence that is not presented.

And hard to believe claims that there are measurable aerodynamic forces acting on two objects separated by the width of a velodrome.

 

[RChung]

One thing for sure, it is not possible to understand evidence that is not presented.

Perhaps. But a second thing is also almost sure: experience has shown that even when evidence is presented you've demonstrated an inability to understand it.

 

[Fday]

And hard to believe claims that there are measurable aerodynamic forces acting on two objects separated by the width of a velodrome.

Well, I guess that puts two on the "disbeliever" list. Of course, he has already stated that the people on that list are probably too stupid to understand the evidence if it were presented to us (or words to that effect).

Perhaps it is quantum mechanics and the two objects on a Velodrome are linked. If that is the mechanism then he is right, I will not understand it nor the evidence supporting it.

 

[RChung]

And hard to believe claims that there are measurable aerodynamic forces acting on two objects separated by the width of a velodrome.

It is hard to believe, isn't it? That's why it's so cool: things we expect to be below the threshold of detection turn out to be detectable.

 

[Fday]

Perhaps. But a second thing is also almost sure: experience has shown that even when evidence is presented you've demonstrated an inability to understand it.

Again, you are giving us your conclusion as to what the evidence shows without presenting any evidence. An example of my failures here (presenting the evidence again) would be just great. I would like to point out that failing to agree with your interpretation of evidence is not quite the same as demonstrating an inability to understand the evidence.

 

[Fday]

It is hard to believe, isn't it? That's why it's so cool: things we expect to be below the threshold of detection turn out to be detectable.

You mean like cold fusion? Someone said it happened and they had the evidence until, well, someone double checked. Let's see the evidence. If this is true, where is the paper? Such a relationship is certainly worthy of a paper somewhere.