The banner ad to the right sez it’s “the most aerodynamic pedal system.”
Does anyone have numbers to support or challenge this claim?
I don’t know the answer to your question, but it would be incredibly difficult to produce any numbers that actually mean much for these pedals.
It’s tricky enough to produce useful data for frames, and much trickier still for wheels or helmets because of the large number of very significant variables that will differ from for every application (e.g. tyre type/size and frame interactions for wheels or head shape/size, head position, body interaction, sunglasses/visor, etc for herlmets). For pedals it seems to me it would be virtually impossible to provide any useful data. At best you could do a selection of example tests and assume that these are representative. I’m not sure you could ever validate that assumption though. For pedals all of the following would have a significant effect and I’m sure it’s not a full list:
shoe modelshoe sizecleat positionfoot angle (constantly changing in both yaw (float) and pitch throughout the pedal stroke and different for every cyclist, maybe even different for the same cyclist on different bikes or different power levels, different fatigue)airspeed (and yaw of bike which is separate to yaw of pedal)cadencecrank lengthshoe covers/overshoes
I’d be fairly confident these Speedplays are more aerodynamic than any others I’ve seen, but I don’t think you’ll be able to quantify it and I don’t think it’ll be hugely significant. I’m on Speedplay zeros now and might consider these in future, but only if it makes them more convenient to walk in. I suspect the single sided pedal, rather than the usual double will be enough to make it a net decrease in convenience!
Your legs churn up air by pedaling. Pedals are in ‘dirty air’ and any aero advantage will be very minimal and very difficult to judge. Jim ar ERO sports has said that they’ve never been able to find the aero differences between a look keo blade and a normal look pedal.
it may be the most ‘aero’ pedal ever, but honestly, I don’t think you’re really gaining anything. It’s really all marketing.
The airflow onto the pedals may be disturbed by the front wheel, fork and skewer. I can’t see the legs having any impact on the pedal’s aerodynamic performance.
The spinning of the pedals mean the angle of attack and airspeed of the shoe/pedal combo will be constantly changing and the airflow will be highly variable throughout the stroke, however that’s not the same as operating in “dirty air”. There are plenty similarities between using “aero” pedals and using shoe covers or more “aero” shoes. The magnitude of the effect may vary and/or be hard to determine but if one is valid I’d find it difficult to say the other isn’t.
The legs won’t affect it as long as it’s stationary. When the start to pedal? You have two huge columns disturbing airflow by moving it around. the air the pedal is moving through will not have nice flow characteristics.
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would agree with this assessment…it would be a sine wave pattern for the path of the pedal given a constant cadence, and will always be experiencing fairly clean air. I would think that shoe aerodynamics could help more than the pedal, so if you took a look at the difference between the most aerodynamic shoe and a standard shoe, you could get an idea of the upper limit of aerodynamic savings from a pedal…BUT this is just some back of the napkin calculations.
Stephen J
Lamson Sports had some pedal shoe combos during Project 96 that were supposed to be significantly more aero. They used a similar shape on the bottom of the shoe that Speedplay’s cleat a pedal form. But truly until someone gets in the tunnel we’ll not know.
If I can source some before our next trip to A2, I’ll see if I can fit those into testing.
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would agree with this assessment…it would be a sine wave pattern for the path of the pedal given a constant cadence, and will always be experiencing fairly clean air. I would think that shoe aerodynamics could help more than the pedal, so if you took a look at the difference between the most aerodynamic shoe and a standard shoe, you could get an idea of the upper limit of aerodynamic savings from a pedal…BUT this is just some back of the napkin calculations.
Stephen J
if you can access it, the study " Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag" by Martin D. Griffith (2014, journal of fluids engineering) would seem to disagree.
to quote: "Though not shown here, the frontal area of the geometry over the crank angle range has been calculated, and though the frontal area varies through the cycle, its variation accounts for no more than 5% of the variation in CDA seen in Fig. 3, indicating a significant change in drag coefficient due to changes in the wake flow with crank angle. " . They also do some studies of vorticity at the crank.
I could be wrong (I’m not a fluids guy- materials here) but large differences in wake flow would indicate non-uniform flow over the entire pedal stroke, no? you are right in that you would see a sinusoidal pattern of disrupted airflow but is that not the common definition of ‘dirty air?’
Lamson Sports had some pedal shoe combos during Project 96 that were supposed to be significantly more aero. They used a similar shape on the bottom of the shoe that Speedplay’s cleat a pedal form. But truly until someone gets in the tunnel we’ll not know.
If I can source some before our next trip to A2, I’ll see if I can fit those into testing.
That would be cool. I would not think the difference would be more than on the order of ~0.001 m², so it’s likely to be very hard to get good and repeatable results on. You also have to be careful with getting the cleats mounted in the exact same spot for all pedals in the test, as this could perhaps wash out any difference. And if you’re comparing to pedals other than Speedplays the difference in stack height is another factor that is likely to influence results.
you think that’s aero you need to try carbon fiber cable crimps. huge.
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would agree with this assessment…it would be a sine wave pattern for the path of the pedal given a constant cadence, and will always be experiencing fairly clean air. I would think that shoe aerodynamics could help more than the pedal, so if you took a look at the difference between the most aerodynamic shoe and a standard shoe, you could get an idea of the upper limit of aerodynamic savings from a pedal…BUT this is just some back of the napkin calculations.
Stephen J
if you can access it, the study " Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag" by Martin D. Griffith (2014, journal of fluids engineering) would seem to disagree.
to quote: "Though not shown here, the frontal area of the geometry over the crank angle range has been calculated, and though the frontal area varies through the cycle, its variation accounts for no more than 5% of the variation in CDA seen in Fig. 3, indicating a significant change in drag coefficient due to changes in the wake flow with crank angle. " . They also do some studies of vorticity at the crank.
I could be wrong (I’m not a fluids guy- materials here) but large differences in wake flow would indicate non-uniform flow over the entire pedal stroke, no? you are right in that you would see a sinusoidal pattern of disrupted airflow but is that not the common definition of ‘dirty air?’
I don’t have access to that study, but from the quote it sounds like they are only looking at the difference in frontal area with different crank angles and write that this difference in frontal area is not enough to explain the differences in drag. But they don’t seem to mention that there might very well also be a change in the coefficient of drag (Cd) of the legs with the crank angle, which could explain the drag differences not explained by frontal area alone - and therefore are not necessarily caused by the movement of the legs.
I spoke with Richard Bryne and we’re going to test these in the near future. We did test Looks, but found no discernible difference.
I think if we do enough runs with riders who provide good, consistent, numbers, we should be able to see the difference. The difficulty lies in the variability of the athlete with each run.
Testing Look vs Speedplay (or any other brands) would be nearly impossible. You need to insure that cleat/foot position is exactly the same across platforms as any changes will effect foot angle which, in turn, changes air flow around the foot. In my opinion, there’s really no way to accomplish this with any confidence in the results. This, of course, is not an issue when testing the same platform without the need to change cleats. With Speedplay, I’d like to test the old zero cleats vs. the new cleats vs the Zero Aero system.
It would be pretty easy to get the same position if you use the same shoes. Ideally, you’d want two pairs of the same shoes to make it easy to switch things out. Tunnel time is not cheap and wrenching on stuff gets expensive quick at over $8.00/min
Lamson Sports had some pedal shoe combos during Project 96 that were supposed to be significantly more aero. They used a similar shape on the bottom of the shoe that Speedplay’s cleat a pedal form. But truly until someone gets in the tunnel we’ll not know.
If I can source some before our next trip to A2, I’ll see if I can fit those into testing.
That would be cool. I would not think the difference would be more than on the order of ~0.001 m², so it’s likely to be very hard to get good and repeatable results on. You also have to be careful with getting the cleats mounted in the exact same spot for all pedals in the test, as this could perhaps wash out any difference. And if you’re comparing to pedals other than Speedplays the difference in stack height is another factor that is likely to influence results.
if you can access it, the study " Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag" by Martin D. Griffith (2014, journal of fluids engineering) would seem to disagree.
to quote: "Though not shown here, the frontal area of the geometry over the crank angle range has been calculated, and though the frontal area varies through the cycle, its variation accounts for no more than 5% of the variation in CDA seen in Fig. 3, indicating a significant change in drag coefficient due to changes in the wake flow with crank angle. " . They also do some studies of vorticity at the crank.
I could be wrong (I’m not a fluids guy- materials here) but large differences in wake flow would indicate non-uniform flow over the entire pedal stroke, no? you are right in that you would see a sinusoidal pattern of disrupted airflow but is that not the common definition of ‘dirty air?’
I would agree that the flow would change through the pedal stroke, but at any non-negative yaw, the air coming across the bottom of the pedal should be ‘clean’. I looked at the abstract of that paper (and thumbnails of the figures; best I could do right now) and it seems to be describing the wake characteristics of the leg and leg/frame interaction of drag with relationship to crank angle. I am not sure that this relates to the question of the pedal aerodynamics on the bottom of the pedal, until you are talking about a negative yaw, but maybe Im missing something without looking closely at the figs.
Stephen J
It would be pretty easy to get the same position if you use the same shoes. Ideally, you’d want two pairs of the same shoes to make it easy to switch things out. Tunnel time is not cheap and wrenching on stuff gets expensive quick at over $8.00/min
Even then it would not be super easy. Is the difference in drag that you observed due to pedals or maybe the position change due to the different stack height of the pedals?
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would agree with this assessment…it would be a sine wave pattern for the path of the pedal given a constant cadence, and will always be experiencing fairly clean air. I would think that shoe aerodynamics could help more than the pedal, so if you took a look at the difference between the most aerodynamic shoe and a standard shoe, you could get an idea of the upper limit of aerodynamic savings from a pedal…BUT this is just some back of the napkin calculations.
Stephen J
if you can access it, the study " Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag" by Martin D. Griffith (2014, journal of fluids engineering) would seem to disagree.
to quote: "Though not shown here, the frontal area of the geometry over the crank angle range has been calculated, and though the frontal area varies through the cycle, its variation accounts for no more than 5% of the variation in CDA seen in Fig. 3, indicating a significant change in drag coefficient due to changes in the wake flow with crank angle. " . They also do some studies of vorticity at the crank.
I could be wrong (I’m not a fluids guy- materials here) but large differences in wake flow would indicate non-uniform flow over the entire pedal stroke, no? you are right in that you would see a sinusoidal pattern of disrupted airflow but is that not the common definition of ‘dirty air?’
I don’t have access to that study, but from the quote it sounds like they are only looking at the difference in frontal area with different crank angles
Nope. They calculated CdA. Moreover, the results of this computatoin study are consistent with direct measurements, i.e., cadence has no measurable impact. That actually makes sense when you consider the relative velocity of leg movement to that of the air passing over them (i.e., as far individual air molecules are concerned, the legs might as well be stationary).
Lamson Sports had some pedal shoe combos during Project 96 that were supposed to be significantly more aero.
And 12 y before that, Puma produced similar “shoe-dals” for the LA Olympics.
I would say exactly the opposite!
If you’re on a stationary trainer in still air then your legs are passing through the same body of air that the pedals pass through a moment later. If the bike is moving forward the pedals trace a path that is a combination of the pedals rotation and the bike’s forward motion (there’s a name for it, it’s similar to a cycloid but I can’t remember). Unless the bike is moving slowly in a small gear, I would expect there to be relatively little if any overlap in this path. If there is no overlap then the situation you are describing does not occur (unless I misunderstand your meaning). Since we’re operating at subsonic speeds and air is compressible there is still some impact but it’s not really worth bothering with for the purposes of this conversation IMO. The front wheel, fork, maybe the downtube could effect the impinging airflow. The legs as far as I can see, will usually not. You’d need to plot the locus of the pedal for a sample case to demonstrate this clearly. It’s easy to do with a CAD programme or a sheet of paper but I’m afraid I don’t have the time or software to do it right now.
I would agree with this assessment…it would be a sine wave pattern for the path of the pedal given a constant cadence, and will always be experiencing fairly clean air. I would think that shoe aerodynamics could help more than the pedal, so if you took a look at the difference between the most aerodynamic shoe and a standard shoe, you could get an idea of the upper limit of aerodynamic savings from a pedal…BUT this is just some back of the napkin calculations.
Stephen J
if you can access it, the study " Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag" by Martin D. Griffith (2014, journal of fluids engineering) would seem to disagree.
to quote: "Though not shown here, the frontal area of the geometry over the crank angle range has been calculated, and though the frontal area varies through the cycle, its variation accounts for no more than 5% of the variation in CDA seen in Fig. 3, indicating a significant change in drag coefficient due to changes in the wake flow with crank angle. " . They also do some studies of vorticity at the crank.
I could be wrong (I’m not a fluids guy- materials here) but large differences in wake flow would indicate non-uniform flow over the entire pedal stroke, no? you are right in that you would see a sinusoidal pattern of disrupted airflow but is that not the common definition of ‘dirty air?’
I can’t read this paper right now, might get a chance later, but from what I see here and your comments, I don’t think it disagrees at all. This study appear to be talking about the effect on drag or the cranks, legs etc… and mention the turbulent wake. I have never disputed that there will be a turbulent wake from the cranks or legs. Of course there will. What I’ve been saying is that I expect the pedal/shoe combo will never be within this wake.
why not, just using a set of zeros and aero zeros, swap pedals(no change in stack or cleat position) and pull the aero walkable cover off(no change in stack or cleat position. this will not be an exact apples to apples as the old zero cleat and new zero cleat are not the same, but it would give an indication of what the cleat cover and pedal do for that particular cleat, which IIRC is smaller in size than the standard zero cleat of old