Originally Posted by
Frankenbike77
I enjoy the added efficiency of delivering power on the upstroke - not as much as I envisioned, but significant nonetheless.
Fyi, studies have not backed that idea up. Here's one thread on it:
Are there any scientific studies proving the benefits of clipless pedal systems? - Bicycles Stack Exchange
"...while torque during the upstroke did reduce the total positive work required during the downstroke, it did not contribute significantly to the external work done because 98.6% and 96.3% of the total work done at the low and high workloads, respectively, was done during the downstroke."
This is echoed in Physiological and biochemical determinants of elite endurance cycling performancepublished in the Medicine and Science in Sports and Exercise 23:93-107, 1991. There are numerous graphs showing that pedal force is only exerted between the top and bottom of the downstroke, represented by a very sharp parabola spiking at 90 degrees from vertical.
I think there have been some other studies suggesting a minor improvement in efficiency, but it's by no means a settled idea that there's any efficiency benefit to clipless.