The Main Elements of the Power Stroke

DID YOU KNOW??

Dr. James Allen Watrous, Ph.D.

Is there more to turning the cranks of a bicycle than simply pushing them? You might think that there is no big deal about getting on a bicycle and pushing the pedals to make it move. And you are partly correct. Perhaps, you have even wondered if there is any other reason for these fancy clipless pedals and shoes other than to help keep your foot on the pedal platform of the bicycle crank.

Indeed, there is far more to pedaling a bicycle than you might have initially thought. This information is useful to all levels of cycling from beginning to pro. Technically there are five parts to the pedal stroke. Two of the five parts are highly technical and primarily needed by advance, racing or pro bicyclists. Some of the details for these two parts of the stroke include elements of transition between the other three parts and elements of ankle use. However, the basic three parts of the pedal stroke are of benefit to all bicyclists. You, most likely, have master one of the three parts – the push down part. The push-down part represents 45 to 55 % of the power that can be delivered to the bicycle cranks. So, where does the rest of the power come from? The other two parts of the bicycle stroke. I refer to these parts as the pull-up and the shuffle. The pull-up and shuffle represent most of the remaining power that can propel the bicycle down the road.

The pull-up part of the stroke uses the hamstrings and calf muscles, whereas the push-down uses the quad muscles. The pull-up part is your second strongest part of the stroke. The shuffle part is the weakest part of the stroke, but is still strong enough to propel you on a flat road at a reasonable speed. The shuffle part of the stroke uses the chin, calf and ankle muscles.

The push-down is the front portion of the stroke. The pull-up is the back portion of the stroke. The shuffle is the top and bottom portion of the stroke.

The Three Main Parts of the Stroke

First step is to become aware of the push-down dynamics. Where does the push-down part become effective? Where does it lose effectiveness in the stroke position (that is, as you push down)? As you ride on a road, become conscious of what position of the crank that the push-down part becomes effective. You should find that to be near or before the 2 o’clock position. You should also find that you lose effectiveness at or near the 4:30 o’clock position.

Next try the pull-up part of the stroke. Do this without pushing down or shuffling. That is, rest the other muscle groups. Beside they need a break. Again, become aware of the crank position that the pull-up becomes effective (about the 7 or 7:30 o’clock position) and where the crank loses effectiveness (about the 10:30 o’clock position).

Finally, try the shuffle part of the stroke. Do this without pushing down or pulling up. For the onset of the top portion of the stroke (shuffle), try kicking out like the front hooves of prancing horses in a circus. For the onset of the bottom portion of the stroke (shuffle), try kicking back like a mule. Admittedly these are crude pictures that should help you create the action of the shuffle portion of the stroke.

Practice each part of the stroke on every ride until you master each part and can do them independently. Next, try practicing any two parts at a time. For example, do the pull-up and shuffle only without pushing down (that is, rest the down stroke), do the pull-up and push-down without the shuffle, or do the push-down and shuffle without the pull-up. Lastly, try all three major parts of the stroke by starting with any one of them. Then add one of the remaining two followed by the last third part of the stroke. Now you are pedaling the entire stroke with power. See the one-legged training section to find another way to improve your stroke power.

Have you ever noticed a bicyclist bouncing on their bicycle saddle? Specially, when that cyclist is trying spin at higher rpm’s. The bouncing is the result of not pulling up and/or kicking out of the shuffle portions of the stroke. In this case, the cyclist is primarily pushing down, which, as the rpm’s increase, causes a noticeable lifting above the seat. As this cyclist adds the other parts of the stroke to power the bicycle, the seat becomes still and much higher rpm’s can be achieved.

One of the major benefits of mastering these three bicycle stroke parts is the improvement of hill climbing. You can use the push-down and pull-up portions of the stroke during a hill climb to improve power. You can also alternate for short times between the two strokes to rest the muscles of the stroke not in use. Any time you are using the pull-up part of the stroke you are lifting the ball of the foot off the bottom of the shoe, which helps relieve the pressure and promote better circulation of the blood in the ball area of the foot. One of the side benefits of less pressure and better circulation in the ball of the foot area is less swelling and tingling of the nerves. This is often referred to “hot foot”.