Study: No Evidence for Superior Time Trial Performances in the “Epo Era”

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Alex Simmons/RST said:
From a practical POV, show me a CFD application and lab that can rapidly test a different skinsuit material or fit, or quickly change bars 5mm between test runs, or see how a rider's slight positional changes impact aero as they fatigue?

No, CFD is a very useful and complementary technology and is definitely great for solving flow problems that cant be solved or tested in other ways, and for visualising what's going on, but practically you just aren't going to achieve the number of level of testing outcomes that you can with field and tunnel testing.
But surely you'll get far more outcomes for a rider's position because the rider doesn't have to be there - you just need his measurements, preferably via a body scan.

And you don't even have to make the equipment so you can change the dimensions easy enough - surely changing some parameters in a computer programme is quicker and cheaper than building the damn thing.

You can run the programmes all year round - find the best handful and then field test/wind tunnel test them.
 
Jul 5, 2009
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Parker said:
But surely you'll get far more outcomes for a rider's position because the rider doesn't have to be there - you just need his measurements, preferably via a body scan.

And you don't even have to make the equipment so you can change the dimensions easy enough - surely changing some parameters in a computer programme is quicker and cheaper than building the damn thing.

You can run the programmes all year round - find the best handful and then field test/wind tunnel test them.
Oh, most definitely not. Setting up your model is the most important aspect and can be very daunting. You also have to factor in that the model of the rider is moving (i.e., pedaling). CFD is an awful way to go in this case.

A much better use of CFD is to use it to explain weird phenomenon that you see during wind tunnel experimentation. Things like, "why did drag decrease when the rider took off his sunglasses"?

At least that's how R&D teams I've been on have used it (non-cycling related projects).

John Swanson
 
ScienceIsCool said:
Oh, most definitely not. Setting up your model is the most important aspect and can be very daunting. You also have to factor in that the model of the rider is moving (i.e., pedaling). CFD is an awful way to go in this case.

A much better use of CFD is to use it to explain weird phenomenon that you see during wind tunnel experimentation. Things like, "why did drag decrease when the rider took off his sunglasses"?

At least that's how R&D teams I've been on have used it (non-cycling related projects).

John Swanson
And how much of that can you do in the half day you have the wind tunnel booked for? And for how many riders?
And with a wind tunnel you can't work out the drag contribution of each component when they are working together.

I've just read that the more advanced teams/bike makers are moving that way and teaming up with car manufacturers to use it - Specialized/MacLaren, Pinarello/Jaguar etc. In his book Michael Hutchinson said that British Cycling stopped bothering with wind tunnels in the run up to 2012 as the results didn't translate to the real world and moved to CFD and track testing instead.
 
D-Queued said:
I think that is what I understand.

Doping should have decreased, or been more moderated, with the advent of the Passport.

Doping should have decreased such that the 'clean' teams can be more competitive.

Certain knowledgeable folks have suggested that speeds are down as a result of decreased doping.

The speed data doesn't support a decrease in doping, even though it is still possible.

Dave.
I should have added that if one believes there is a steady increase in speeds decade after decade, unrelated to doping, and factors that in for the comparison between the 1990s EPO era and the post-EPO or Perneger era, then speeds do decrease going from the EPO to the post-EPO era. I.e., if the speeds are the same, but there is some technological or environmental benefit that is constantly benefitting speeds over the years, then the fact that the post EPO era, with this benefit, still is no faster than the EPO era indicates that the post EPO riders are effectively slower, would be slower without this benefit.

So one could argue there is less doping since the 1990s. Again, the difference is not significant, but again, one would not expect the difference to be significant, given all the scatter. There is too much variation inherent in this approach to conclude with any certainty that there are changes in speed at any point that could reflect more or less effects of doping.

So there are two problems with the authors' claim that their data provide no evidence of doping: 1) there is not enough certainty in the data to pick up this effect, if it exists, at a significant level; and 2) what insignificant effect does exist does support the existence of doping in the 1990s and less in the following years.
 
ScienceIsCool said:
Oh, most definitely not. Setting up your model is the most important aspect and can be very daunting.
this. It's a big job to create a good model. It's the biggest part of the job. You can't simply scan a rider once. You'd have to scan them for every positional change while on their bike. It'd take longer than just doing the test in the first place. And CFD can't effectively test for things like different fabrics, or changes in wrinkles, or a dynamic rider movements.
 
Parker said:
And how much of that can you do in the half day you have the wind tunnel booked for? And for how many riders?
And with a wind tunnel you can't work out the drag contribution of each component when they are working together.

I've just read that the more advanced teams/bike makers are moving that way and teaming up with car manufacturers to use it - Specialized/MacLaren, Pinarello/Jaguar etc. In his book Michael Hutchinson said that British Cycling stopped bothering with wind tunnels in the run up to 2012 as the results didn't translate to the real world and moved to CFD and track testing instead.
CFD is good for design of components, frames, bars etc, less so for the dynamic of a rider.

You do realise that track testing is field testing?

With track testing we can use the time more efficiently than in a tunnel, because we can alternate riders on the track, capturing data for rider on track while changes are made to those not on track. Can't swap rider so easily in a tunnel. But we do tend to use longer data runs than a tunnel, so I guess the runs per hour/rider is similar.

Edit: to add, the most time consuming part of testing is making the change to the bike. Some changes are quick/easy, others take longer - depending on bar set up. Testing helmet for instance is a very quick change over.

Parsing out individual components is not always of much help, since the effects are interrelated, a change to one component can affect the impact of another. What matters is controlling for the change and assessing the total impact. In that way you progressively and iteratively work towards an optimal aero set up.

Setting up high quality grids for CFD for a complex shape as a cyclist on a bike is very time consuming, not mention going through validation processes such as grid convergence testing.
 
Based on information I've read from studies directly comparing wind tunnel testing with best practice CFD simulation of the aerodynamic drag on cyclists (e.g. work by Defraeye, Blocken et al) they themselves suggest CFD has a typical accuracy of about 10%.

That's with best practice and using a static model. I'm afraid this level of accuracy is well below the requirements needed for reliable assessment of riders. We are typically teasing out differences of around 0.001 - 0.002m^2 (i.e. less than 1.0%).

With some riders the precision is lower though, as people are dynamic beasts.
 
Alex Simmons/RST said:
Based on information I've read from studies directly comparing wind tunnel testing with best practice CFD simulation of the aerodynamic drag on cyclists (e.g. work by Defraeye, Blocken et al) they themselves suggest CFD has a typical accuracy of about 10%.

That's with best practice and using a static model. I'm afraid this level of accuracy is well below the requirements needed for reliable assessment of riders. We are typically teasing out differences of around 0.001 - 0.002m^2 (i.e. less than 1.0%).

With some riders the precision is lower though, as people are dynamic beasts.
It still doesn't address the problem that for a wind tunnel you need the rider to actually be present. Time is the biggest constraint. How many positions can you test in a two hour slot once a year? And how many can you test with CFD in a year? They're testing busy world class athletes not student volunteers.

Alex Simmons/RST said:
You do realise that track testing is field testing?
Yes, of course I do.

Alex Simmons/RST said:
Edit: to add, the most time consuming part of testing is making the change to the bike. Some changes are quick/easy, others take longer - depending on bar set up. Testing helmet for instance is a very quick change over.
No, the most time (and money) consuming part is making the equipment.

But still maybe you're right. But teams are increasingly using it.
 
Oct 16, 2010
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perhaps this is all about Cookson getting back at Vino over London 2012?
Cycling medal table Olympics 2012:

1 Great Britain 8 2 2 12
2 Germany 1 4 1 6
3 France 1 3 0 4
4 Australia 1 2 3 6
5 United States 1 2 1 4
6 Colombia 1 1 1 3
7 Netherlands 1 0 2 3
8 Kazakhstan 1 0 0 1
 
Jul 5, 2009
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Parker said:
It still doesn't address the problem that for a wind tunnel you need the rider to actually be present. Time is the biggest constraint. How many positions can you test in a two hour slot once a year? And how many can you test with CFD in a year? They're testing busy world class athletes not student volunteers.


Yes, of course I do.


No, the most time (and money) consuming part is making the equipment.

But still maybe you're right. But teams are increasingly using it.
I'm sorry Parker, but everything I've seen indicates that CFD is great as a diagnostic tool and is inexpensive, but it makes for a lousy substitution for putting an object into an airflow.

As an aside, the reason that wind tunnels kind of suck for cycling applications is the very low speed nature and the desire to get very high precision. In a wind tunnel, the airflow isn't perfect and drops to zero at the walls so it's necessary to put the cyclist on a pedestal into the stable part of the flow. But then the pedestal disturbs the flow... You also need to build something that rotates the wheels at exactly the same speed as the airflow and measure the torque on the wheels. All this adds uncertainty to the measurement.

There are better ways, but they are very complicated to design.

John Swanson
 
May 26, 2010
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ScienceIsCool said:
I'm sorry Parker, but everything I've seen indicates that CFD is great as a diagnostic tool and is inexpensive, but it makes for a lousy substitution for putting an object into an airflow.

As an aside, the reason that wind tunnels kind of suck for cycling applications is the very low speed nature and the desire to get very high precision. In a wind tunnel, the airflow isn't perfect and drops to zero at the walls so it's necessary to put the cyclist on a pedestal into the stable part of the flow. But then the pedestal disturbs the flow... You also need to build something that rotates the wheels at exactly the same speed as the airflow and measure the torque on the wheels. All this adds uncertainty to the measurement.

There are better ways, but they are very complicated to design.

John Swanson
Froome was not in a wind tunnel before he won the TdF, IIRC.
 
May 26, 2010
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red_flanders said:
I reject the idea that we know anything, if all we have to go on is statements from Sky. He could have been in there every day.
True, whatever sky have released can be taken with pinch of salt.....
 
Parker said:
It still doesn't address the problem that for a wind tunnel you need the rider to actually be present.
You need the rider to be present as well to do the CFD mesh scans for every possible set up you might wish to test for. Each time you make a change to bike set up, the rider's morphology changes in many subtle ways a computer model can't possibly predict.

Then you need time to make the changes to the bike and redo the next scan. I just don't see where the time saving is.

The next problem with that type of approach is it's no longer an iterative process, whereas live testing is. You see the result of a run, make a change and see the result, then decide from there which direction to take with the next change. With CFD you are confined to testing only the set ups you've scanned for. Live iterative testing reveals outcomes you may not have considered testing for originally.

Even then, what's the point of testing a virtual rider with CFD if the error range in CdA is 10%?

Aerodynamics is very complex and the smallest things matters. Small trips at the right place can make a 5-10W difference in power required at same speed. Different jersey material makes a difference. A CFD mesh for of an object the size of a rider just doesn't have that kind of resolution.

Teams might be using it, but I bet they are not relying on it for actual data about their riders on a bike. For that they do tunnel or field tests. Or nothing, which is what most of them do as they have to ride the sponsor's jersey, helmet, bike, bars, wheels, tyres etc in any case.

It's rare for a pro to be riding an optimal set up. They are not paid to ride an optimal set up, they are paid to ride the sponsor's kit. The objective of testing in that case is to find the best option within the constraints placed upon their equipment choices.

Parker said:
Time is the biggest constraint. How many positions can you test in a two hour slot once a year? And how many can you test with CFD in a year? They're testing busy world class athletes not student volunteers.

No, the most time (and money) consuming part is making the equipment.

But still maybe you're right. But teams are increasingly using it.
How many options can I test? Depends on what we are doing, but I'll get around 8 -10 runs per hour per athlete, usually can do two riders in parallel.

A busy world class athlete that cares about performance will make the time to test for things that will help their performance. Most actually love doing that sort of thing, experimenting - it's actually fun doing it.

Here's an example from a teaching session I ran earlier this year. Focus in this case was teaching others (bike fitters) about the impact of various things and the process, so it wasn't a full on "let's really nail this guy's position" session.



You'll note for instance the difference in CdA depending on which skinsuit he was using. No CFD model is ever going to tell a rider which skinsuit he should use.
 
Parker said:
...

No, the most time (and money) consuming part is making the equipment.

...
When did they start making equipment in wind tunnels?

ScienceIsCool said:
I'm sorry Parker, but everything I've seen indicates that CFD is great as a diagnostic tool and is inexpensive, but it makes for a lousy substitution for putting an object into an airflow.

...
This.

Alex Simmons/RST said:
...

Aerodynamics is very complex and the smallest things matters. Small trips at the right place can make a 5-10W difference in power required at same speed. ...

...

It's rare for a pro to be riding an optimal set up. ...
And this.

The latter point underscoring that, at least in the past, lots of drugs >> minor wind tunnel improvements.

When Eki was riding with Lance, for example, he was convinced that descending with one foot down was more aerodynamic than with the pedals parallel to the ground. While tunnel testing disabused him of the notion, it is a good example of where pros are at.

Conclusion?

He must have been able to compensate for stupid aerodynamics in other ways.

Dave.
 
D-Queued said:
When did they start making equipment in wind tunnels?

This.

And this.

The latter point underscoring that, at least in the past, lots of drugs >> minor wind tunnel improvements.

When Eki was riding with Lance, for example, he was convinced that descending with one foot down was more aerodynamic than with the pedals parallel to the ground. While tunnel testing disabused him of the notion, it is a good example of where pros are at.

Conclusion?

He must have been able to compensate for stupid aerodynamics in other ways.

Dave.
I was just saying that teams are moving towards CFD. Maybe McLaren and Jaguar are wrong and you're right (I know they won't have as sophisticated systems as Mr Simmons with his multi million pound budget). I don't know who you are so you may very well know more than F1 teams - particularly with your bang up to date referencing of Ekimov. So maybe you're right.

But the fact is that OPQS, Sky and British Cycling, at least, have moved more towards CFD. Maybe they should read more internet forums.
 
Sep 29, 2012
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D-Queued said:
When Eki was riding with Lance, for example, he was convinced that descending with one foot down was more aerodynamic than with the pedals parallel to the ground. While tunnel testing disabused him of the notion, it is a good example of where pros are at.
I never saw that claim, but for cornering it's faster, pushing the weight down, so you'd descend faster, so perhaps that's the mistake he made?
 
I emailed one of the authors of the study linked in the OP, raising the criticisms I posted upthread. He got back to me very quickly.

I’m not going to post his reply, but below I am posting my reply to him, which will make clear what his points to me were, as well as my response. He also sent me some of his statistical analysis, and a new paper, "The Epo Fable in Professional Cycling: Facts, Fallacies and Fabrications", a continuation of his argument that the effect of EPO is exaggerated.

There are several arguments made in this new paper: 1) a meta-analysis of 17 studies of EPO shows relatively little effect on performance. That’s based on another study of his, and I comment on this in my reply, posted below. ; 2) historical studies of speeds in stage races and time trials, including the data in the Texas Sharpshooter paper as well as studies by others referred to in that paper; and 3) LA's time trial speeds, data originally presented in a paper about two years ago. That is actually the first of three papers in a series comparing LA's performance to historical ones, the others are at:

http://pubs.sciepub.com/ajssm/2/5/4/ajssm-2-5-4.pdf

http://pubs.sciepub.com/ajssm/1/4/3/

Note that the third paper is a study of mountain time trials. I also comment on this in my reply to him, posted below:

Thanks so much for your quick response. I appreciate it.

You say, “First of all, I am not saying 'there was no doping' (after all we do not know that, do we?). I am only saying there is no discontinuity in performance in the epo years. So my conclusion that the effects are probably overrated.”

But what counts as a discontinuity? Your analysis shows that there is a 1.5% increase in speeds in the 1990s above and beyond the 0.160 kph per year increase observed over the previous sixty years.

You continue, “How do you know this 1.5% increase is due to the effect of doping? I dare you to prove it. I can name a host of alternative factors that may explain this increase which are as just as plausible. Moreover, look at the steady increase in performance over the years. Why should the progress in the epo years be due to the effect of epo? What about the progress in the 40s , 50s, 60s, 70s, 80s, 90s? Are they due to other doping substances?”

I emphasized that I can’t prove this increase resulted from doping. But it’s certainly consistent with it. In fact, your meta-analysis of EPO studies, which I will get to in a moment, shows that this is just the kind of increase we would associate with doping. But the point here is that the burden of proof is on you to account for this increase, since you’re the one making the statement “there is no discontinuity in performance in the EPO years”. There isn't a huge discontinuity, but there does appear to be some.

Also, I think at least some of the increase during the earlier years probably was due to doping. Just because riders didn’t have EPO available doesn’t mean that the substances that were available couldn’t help them. Any drug that increased power, recovery or alertness, as substances of that era generally did, would help a rider ride faster.

With regard to the Perneger years, I can only say again that I think you have flipped the difference (0.89 kph) around. You reduce the difference in speeds between the EPO era and the previous era by subtracting out the steady increase in kph expected over those years. The 1.5% difference is what remains after this correction (and a smaller one for distance). To be consistent, you should do the same in a comparison between the Perneger era and the EPO era. Since the raw data indicate the speeds in those two periods are the same—this is also evident in Fig. 2, and you yourself speak of a leveling off beginning in the EPO era--the corrected data must indicate that speeds were lower in the Perneger era. In other words, if you assume that this steady increase continues throughout the early part of this century, the speeds of the riders benefit from this, which means if they didn’t have this benefit, they would be slower than the speeds of the 1990s, in just the same way that the speeds of the 1990s are concluded to be not much greater than the speeds of the previous era. If there is some other way you can come up with a greater speed in the Perneger era, you have not been clear about it at all in your paper.

Finally, with regard to the effects of EPO. As I’m sure you’re aware, the worst abuse of this drug was prior to the 50% HT rule, when riders could take as much as they wanted, far more than would be used in any academic study. Even after the rule was imposed, in 1997 I believe, there was a period of several more years before a test for EPO was developed, which meant riders with a naturally low HT could still take very large amounts of it. After the test was instituted, riders tended to switch to blood transfusions, with EPO frequently being used to mask the suppression of reticulocytes normally accompanying such a transfusion.

So I think there are reasonable questions about whether most of the available studies gave volunteers dosages of the drug comparable to what riders took at the height of that era. However, even with that limitation, your meta-analysis found an increase of 6-7% in V02max and 7-8% in power. You seem to think this is trivial, as it will result only in a maximum gain in speed of around 1 kph in a TT, roughly 2 – 2.5%. But again, because of the power/speed relationship in TTng, one would not expect a large speed effect. This increase is in fact fairly consistent with the 1.5% increase—to repeat, above and beyond the steady 0.16 kph per year increase—your own analysis found for the 1990s.

Moreover, an increase of 7-8% in power would correspond to the same 7-8% increase in speed in a climb. This could reduce the time of a 40 minute mountain top finish by more than three minutes, which is an enormous benefit. It’s the difference between winning the stage and not even finishing in the top 10, and added up over a Grand Tour, the difference between winning or podiuming, and again, not top 10. And this does not even take into account at least one study that reported that time to exhaustion is increased far more by EPO—up to 50%--than V02max, nor the effect in conserving energy over time in a stage race.

I understand you did analyze a few mountain time trials, but the number is relatively small and includes widely different gradients, even within some ITTs, as well as between different ones. You did develop a climbing index, but as far as I can see, this does not take into account that variation in slope has a major effect on wind resistance, which in turn means that power/speed relationships can be very complicated. About half of the 19 TT you analyzed had a climbing index much smaller than the mean slope, which if I understand correctly means there was a large portion of flat or gentle slope riding (e.g., the first half of so of Armstrong’s mountain TT in 2001 was relatively flat or at most gently sloping). The problem becomes even worse when weather conditions are not taken into account.

So while your analysis is certainly a welcome addition to the debate over the performance effects of doping, and no doubt the best possible using time trials, I think the best measures of climbing remain stage finishes which have a fairly steep and constant gradient. You are surely aware of the enormous differences between Alpe D’Huez times in the 1990s, and those before or after. While some of the differences, particularly with respect to earlier years, can be ascribed to different racing strategies, no rider after the opening years of this century has come close to the best times of the EPO period. To the best of my knowledge, the top 15 or so fastest times all occurred between 1994 and 2004, with no rider since within two minutes of the fastest time.

The final TT in your table in that analysis is Armstrong’s ride up ADH, one of the fastest, and his speed there does exceed his predicted speed, which is based on a steady increase of about 0.2 kph year over the period of analysis. You argue there that the difference is not that large, but if that’s the case, why have all subsequent climbs up ADH been so much slower? There is the fact that they occur at the end of a long stage, whereas Armstrong in 2004 climbed ADH as a TT, but if riders today can’t come close to the ADH times of the EPO era, which were also at the end of a long stage, that surely strongly suggests that they would not come close to Armstrong’s 2004 time trial, either (when he raced ADH three years earlier, at the end of a stage, he was only about 30” slower). Which means, at the very least, that the steady increase in climbing speeds over time has not simply leveled off, but reversed. And it underscores my earlier point that much of the effect of EPO and other forms of blood manipulation are likely to be in greatly enhanced ability to conserve energy, during a stage as well as between stages.
 
I
Dear Wiggo said:
Speeds seems a little irrelevant without duration yeah?
Winning average speeds across multiple races - especially ITTs - is a bit of a red herring. It's not just duration, there's also:

Elevation (altitude and climbing elevation)
Ambient temperature
Humidity
Road condition
Wind strength and direction
Field strength and start order
Placement of TV motorbikes and helicopters
Difficulty of the previous stages (applies to stage races only OFC)
How well the team mechanics prepared the bike
Etc, etc etc

There are some glaring holes in this study, that's for sure :rolleyes:
 
Parker said:
I was just saying that teams are moving towards CFD. Maybe McLaren and Jaguar are wrong and you're right (I know they won't have as sophisticated systems as Mr Simmons with his multi million pound budget). I don't know who you are so you may very well know more than F1 teams - particularly with your bang up to date referencing of Ekimov. So maybe you're right.

But the fact is that OPQS, Sky and British Cycling, at least, have moved more towards CFD. Maybe they should read more internet forums.
Are you confusing bicycle design with real persons?

CFD makes a lot of sense for component design. And for working with models and mannequins (i.e. known bodies with consistent parameters).

To fine tune a cyclists actual position, though, you need to put that person into positions that they can achieve and test them in a controlled environment.

wrt the Ekimov example, at least I'm not trying to fudge a lack of specific knowledge.

Dear Wiggo said:
I never saw that claim, but for cornering it's faster, pushing the weight down, so you'd descend faster, so perhaps that's the mistake he made?
The reference was specific to aerodynamics, not to technique.

Merckx index said:
I emailed one of the authors of the study linked in the OP, raising the criticisms I posted upthread. He got back to me very quickly.

...

So while your analysis is certainly a welcome addition to the debate over the performance effects of doping, and no doubt the best possible using time trials...
Hmm, I don't think he really welcomed your analysis at all.

Another anecdote, second hand, was that Lance's power output apparently increased over the three weeks of the TdF while that of his key rivals decreased as would be expected.

EPO is only one of the tools in a very comprehensive toolbox. There was a lot of sophisticated doping going on.

Dave.
 
Parker said:
I was just saying that teams are moving towards CFD. Maybe McLaren and Jaguar are wrong and you're right (I know they won't have as sophisticated systems as Mr Simmons with his multi million pound budget). I don't know who you are so you may very well know more than F1 teams - particularly with your bang up to date referencing of Ekimov. So maybe you're right.

But the fact is that OPQS, Sky and British Cycling, at least, have moved more towards CFD. Maybe they should read more internet forums.
As I have already pointed out, use of CFD is not so much for the dynamic organism that is a human body. For components / frame design it makes sense, which is what BC used it for - the design of frames and helmets. But even then it has to be verified with actual wind testing.

Here's a CFD reference discussing the use of CFD by BC:

http://tinyurl.com/q2hmfb9
 

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