Crank Phase Change Followup

We have done two “regular” rides now on the tandem after configuring the cranks in phase (front and back pedals fully sychronized). IP = “In Phase”; OOP = “Out Of Phase”. For most of the past ten years we have ridden in various OOP configurations, mostly 90 degrees out of phase, in order to provide some power to the drive train pretty much all the time. Note that more than 90% of tandem bikes are set up with the pedals IP.

It has been shown that even pros, the riders with the smoothest pedal strokes, still provide most power to the pedal on the down-stroke. Pedaling circles is certainly helpful, but nobody can pull up with the same force as they push down.

Now, when you have two people turning the cranks, as you do on a tandem, the theory is that with the cranks in phase, you end up with an exaggerated surge twice each revolution (right leg, left leg). The last time Kathy and I tried IP, we tried to pedal up our first hill while standing on the pedals, and experienced this surge big-time. By the time we reached the top of the hill, we both wanted to immediately change back to OOP.

In a recent post I explained that we decided to give IP a serious trial because an initial test resulted in much decreased upper body movement for Kathy. We were concerned that her rocking back and forth was exacerbating lower back pain she was experiencing.

On our two rides since going back to IP, we have found ourselves riding significantly faster. During this same period of time, I have been training hard, but I cannot believe that I suddenly became so much stronger; it has to be the phase change. I am very surprised, and can’t quite explain it, but there it is.