ZENcranks PAS testing by Velo

Not to be confused with Sugino’s Zen track chainrings, this crankset’s full name is Zencranks PAS (Power Augmentation Systems), and you’ve never ridden anything like it. I performed a long-term review on the system, comparing it to two conventional cranks,

one of standard length and one of comparable length to the Zencranks. I was beyond skeptical when I first saw the system, but came away surprised at how well they worked in terms of climbing speed.

 

Zencranks have the pedal bearings built into each crank arm and an extension arm pivoting at that point, which is connected to the pedal, whose spindle will not rotate. The system makes the trajectory of the metatarsals of the rider’s foot far more egg-shaped than with most pedal systems.

Zencranks are the brainchild of Dr. Zeno Zani, who achieved fame for positioning Italian cycling stars like Marco Pantani and Mario Cipollini on their bikes. He has written two books about bike positioning, Pedal Well and Disorders and Remedies of Poor Bike Positioning.

When I first received these cranks directly from Zani and his business partner, Stefano Doldi, two years ago at the Italian Expobici show, it took me a long time to get them on my bike, and that was not entirely because their FRM bottom bracket system is more of a pain to install than most. I disbelieved Zani’s assertion of the value of this egg-shaped foot trajectory, especially his claim of a 50-watt increase in power output, since I had been trained to believe in the benefits of a round pedal stroke. I had long drunk the Kool-Aid from Time, Shimano, and others of the efficiency to be gained by getting the foot as close as possible to the center of rotation of the pedal, whereas Zencranks greatly increase that distance. Until I looked at them closely, they reminded me of the articulated cranks on which Paula Newby-Fraser won the Ironman in Kona a few times, but they are actually diametrically opposed to Newby-Fraser’s cranks in function.

Zencranks come from the opposite philosophy of Shimano Dyna-Drive cranks and pedals on Dura-Ace EX and AX and 600 AX groups (on which Alexi Grewal won the Olympic road race in 1984). Modern equivalents for those whose memories don’t go back that far are the Side-Mount Pedals or the Vista Magic pedals. Rapid bearing wear and the appearance in the mid-1980s of clip-in pedals killed Shimano Dyna-Drive pedals.

After Look clip-in pedals had the market cornered for a few years, the pedals’ inventor, Jean Beyl (also the inventor of the spring-release ski safety binding), left the company and came up with the Time pedal. From the beginning, Time’s claim to greater efficiency was not only that its pedal offered free-float but also that it also brought the foot closer to the pedal spindle than did the Look pedal. Time explained this reduced “rocking torque” as an efficiency-robbing demand on the leg muscles forced to constantly work to keep the foot over the pedal spindle.

With clip-in pedals, we had lost the perfect circle traced by the head of the first metatarsal that Dyna-Drive had offered. Instead, all we could do was try to get the foot closer to the spindle, and the popularity of pedals like Time, Speedplay, and Keywin can partially be attributed to this. But now Zani wishes to change our minds and get our feet much further from the pedal platform.

Read the rest of the review on VeloNews:  Putting the Zencranks through the paces