"I'm at the Speedplay Booth. Their leg mannequin has the biggest ass I've ever seen."
While I appreciate bike technology in all forms, I can't stand the inglorious ways by which people try to sell it to you. Readers may know that I run a section on this site titled "Marketing Mishaps". For some time now, I have been collecting events in our biking world that seem fit for it, you know - haphazardly done marketing through poor science, cheesy ad material and other nuances that just turn intelligent people off. I think I have found some new material today.
- someone at Interbike this year.
I present to you the "Slippery Speedplay Mannequin". It's all slippery (and smoke and mirrors too) if you read on.
Dynamic Test Procedure : Quickly, here's a summary of what Speedplay did to try and back up the superiority of their pedal design, the Zero. They placed the mechanized legs of an impressive mannequin (only legs) on a bike in the San Diego low speed wind tunnel. The legs were attached through cleats to the Zero pedals. The contraption was then made to pedal for a mere 5 minutes at 100 rpm in a normalized wind velocity of 30 mph. Apparently the tech guys did this twice with a 3 hole and a 4 hole mounting sole to capture any differences from mounting. Finally, they compared the results to the same procedure done to two other competitor pedals from Shimano and Look (brand was kept secret).
What To Measure? : Speedplay was interested in measuring the drag co-efficient, Cd, multiplied with frontal Area, A of the mannequin and bike system. This term appears in the equation for retarding drag force in cycling. I have written the equation for you below and what the terms mean :
It appears that even Speedplay is muddled with the terms and their definitions. In several places, they write as if they're measuring the term drag co-efficient Cd when even the computer screen in their report shows "CdA". On top of that, they take this to be a dimensionless quantity. I wonder what kind of drink the author may have had the night before?
Where Measured : San Diego Low Speed Wind Tunnel at the Air & Space Technology Center. Test section dimension of facility is 2.44 x 3.66m. Test section cross-sectional area is 8.50m^2.
Results : Going with the poorly presented results of the test, here's what I think I gleaned from it. Tabulated for you, these numbers are for one test for each item, for a duration of 5 minutes and 100 rpm cadence. Please note, all these numbers are claimed by Speedplay. The percentage differences between each line item were done by me.
Conclusions To Customers : Speedplay goes on to claim that their calculations show such drag reductions result in a time saving of 5.5 seconds/hour and 33 seconds/hour for 3 and 4 hole mounts respectively. This, they say, is equivalent to the savings gained from replacing a standard wheel with a deep section, aero front wheel.
The fishy things going on in this whole agenda are the following :
1. Time savings for whom? : While the contraption is really impressive, the 33 second savings computed by Speedplay, if correct, are for the lower legs of a "robot" riding into 30 mph headwind in a wind-tunnel specifically with 4 hole mounted cleats. C'mon, even an ape won't believe that an actual human being using this will get the same amount of claimed benefits.
2. As opposed to what? : The number of pedals in the test are small (2) and the specific brands chosen have been hidden from us. Which is understandable but again, I suppose any idiot could test the Zero pedals with a competitor's junk hardware from the past years and say that it's better. Were all brands tested the latest in market?
3. 33 seconds savings, really? : Those claimed savings seem artificially huge to me. Just for an illustration, the 2004 Nike "Swift Spin" time trial suit prototype (with tracksuit and leggings), worn by a pro cyclist, showed a time savings of 33 seconds when pedaling into 32 mph wind, over its 2003 development model. This suit is still considered by many to be state-of-the-art stuff and a production model was used in a couple of Tour de France's. To claim that switching to a small pair of pedals under a robot's legs equal the time savings of a top aerodynamic piece of apparel worn by a actual human in aero position points to something extremely fishy in the calculations. It even diminishes the many years of work Nike and other researchers conducted in trying to create a more aero suit for pro cyclists.
4. Where's the math? : Obviously, what Speedplay fails to show is the methodology behind their conclusions. How did they arrive at 33 seconds/hour time savings? Moreover, they don't investigate the variation of CdA numbers as the sample size increases by limiting themselves to one test run for each type of pedal. The worst part is, they test each pedal for 5 minutes. Hence, we don't have an indication of the level of error and range of CdA values over many trials. Now you have to ask, is this really 33 second time savings? Or something smaller?
As is apparent to others, Speedplay wants you to buy their Zero Pedals which will free you of between $130-$330 (Chromoly-Titanium). They calculate that if you cut your legs apart, dispose of the trunk and then pedal a bike in a rare and bloody time trial of 5 minutes keeping everything tight and in-plane like a mannequin, you'll save as much time riding into a 30 mph headwind as does tossing out a 32 spoke wheel for a slick aero wheel in the front.
RELATED DISCUSSION FROM OTHERS :
Cyclocosm : Are You A Speedseeking, Torso-less Pair Of Legs?
Alien Biker : The Missing Link, The One Piece Of Gear That Will Help You Ride Like A Pro
Slow-Twitch Forums : Speedplay Claims Huge Wind Drag Reduction Over Leading Brands
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