06 April 2016

More Aerodynamic? More Ergonomic? Maybe Not, But They Were Pretty

A few posts ago, I mentioned the Shimano Dura-Ace aerodynamic (EX and, later, AX) components of the early 1980s.  While the components themselves didn't catch on quite as much as Shimano hoped, they had (and still have) their devotees. More to the point, they have their influence on today's components and bikes.

Perhaps no part of the EX system better epitomized the ensemble's inability to catch on with the cycling public and its long-term impact than the Dyna-Drive pedals. 


The Dura Ace EX Dyna-Drive (DD) crank was actually a lovely piece of work and would look as appropriate on a current bike as one of the era, or even an earlier time.  It resembled other Dura Ace cranks made since, more or less.  Its spider and pedal arm have a finish and shape like those of its successors, save for the flare near the end of the crank arm.  There was a reason for that:  the pedal mounting hole was about double the diameter of that on any other crank. 

That oversized pedal hole was made to accommodate the DD pedal, which had eliminated the through-axle found in most pedal bodies in favor of something shaped more like a plumbing joint that mounted outboard of the pedal.  The bearings were inside of it.  In contrast, most pedals have a set of bearings inside each end of the body.

In addition to lighter weight (about a third less than Campagnolo and other quill-caged road pedals of the time), this setup, because of the size of its mounting, was supposed to be stiffer. I never used the pedals or crank myself, but I knew a couple of cyclists who did and wouldn't use anything else. 



The mounting system also resulted in a pedal platform that was lower than, rather than level with, the center of the mounting hole in the crank arm.  As a result, at the bottom of the pedal stroke, the bottom of the foot was lower than the pedaling axis.  This was supposed to offer better biodynamics in the pedal stroke, which would lead to a more even power transfer throughout the rotation of the pedal. 

To me, it sounds like the benefit the Biopace (slightly elliptical) chainrings Shimano would make around the same time.  As I mentioned in an earlier post, I never used Biopace for any length of time, so I can't say whether or not they actually offered the claimed benefit.  Likewise for the DD pedals, which I never used.  I will say, however, that the few cyclists I knew who used them liked them very much.

Shimano made adapters so that conventional pedals could be used with DD cranks, or so that DD pedals could be used with conventional cranks.  I don't know anyone who used those, but I saw some cyclists ride conventional Dura Ace cranks and the pedals of their choice with the other aerodynamic EX parts.

Eventually, the 600 racing series and the then-new Deore touring and mountain bike parts would also offer the Dyna Drive option.   They were even less popular in those ensembles than in Dura Ace.  It makes sense, especially for the touring ensemble:  If your DD  pedal hit a curb or got snagged on a rock or tree root in the middle of nowhere, you probably wouldn't find a replacement--or even an adapter--in the local farm machinery shop where bike repairs are done.

Still, those pedals have had a lasting influence:  Look and other contemporary pedals, while they don't completely eliminate the through-axle, use a shorter axle than on earlier pedals.  More important, though, they use one set of oversized bearings on the side of the pedal that mounts to the crank, eliminating the bearing on the outer part of the pedal.  This makes lighter, more streamlined pedals possible. 

And, of course, the shapes of many of today's pedals owe much to the aerodynamic design of DD pedals, which in turn were influenced by the Lyotard No. 23, a.k.a. Marcel Berthet, platform pedal.


  1. I know Shimano had all kinds of "biomechanical" reasons behind that DD pedal, and having the pedaling axis slightly below the center of the axle -- but I've always been highly skeptical of such claims.

    I remember how that aero/AX concept spread out to other Shimano groups, like 600, and even a low-cost group called Adamas. The Adamas group was put onto a Huffy with squashed tubes and called the "Aero Wind." The frame tubes looked like they were literally just squashed (like in a vise or something), as they were flattened in the middle, but still round at the welded joints -- and mostly it was the same basic frame design used on all their other department store junk.

    Interesting little aero note -- the aero-design centerpull brakes (either the Dura-Ace or 600, I don't remember which) were used in the early 2000s on Tour de France time-trial bikes for He-Who-Must-Not-Be-Named.

  2. Brooks--I remember that Huffy bike. It was indeed junk. If I remember correctly, Huffy had a TV ad for it that included the Christopher Cross song "Ride Like The Wind".

    I also remember the "Admas" group. It included one of the strangest pedals I've ever seen. Its shape bore absolutely no resemblance to the sole of any human foot.

    To tell you the truth, I never understood the "biomechanical" reasons behind the DD pedal or, for that matter, the Biopace chainring. Sometimes I wonder whether Shimano did.