You can pedal a bike well enough to get by, or you can pedal a bike efficiently and get the most out of the incredible mechanical advantage that’s available. To make the most of your gearing and aerodynamics you must use all the leverage available at your bike/body connection – your bike’s crank arms. For anyone who’s tried to loosen a tight nut or bolt with a wrench, the advantage of maximum leverage is simple to understand. This same leverage principle applies to optimal energy transfer at your crank arms. To loosen that bolt, or apply maximum pressure to the cranks, the force applied should be perpendicular (at a 90 degree angle) to the lever (crank arm), and the further from the pivot point that you push on the crank arm the more force you generate. On a bike, the pivot point or fulcrum is the axle of your bottom bracket, and the length of your lever (crank) determines maximum leverage. This potential won’t change unless you install longer cranks, but your cranks are likely already at maximum length for effective pedaling in proportion to your leg length. So this leaves the angle from which you apply pressure to the crank arm as the only variable you can modify (besides increasing force/wattage output from the engine—you). This is challenge for some cyclists, but the rewards are well worth the effort!
The simple exercise of just pushing down on the cranks to make the bike move becomes more complicated. As an example of wasted energy: consider what happens when you simply push straight downward with the crank arms at the 12:00 o’clock and 6:00 o’clock positions—absolutely nothing. We all learned this early on when we struggled through our first few pedal strokes on that little tricycle or coaster-brake bike. Have you ever watched a child try to get his or her bike moving when the pedals are in this position? After a while it becomes clear that in order to get the child started you have to either give a push, or pick the bike up and rotate the cranks 90 degrees to 3 and 9 o’clock positions. Optimal pedaling technique is no more natural than a perfect swim stroke, it must be learned.
To get the most out of your cycling, you need to analyze your pedal stroke and identify the weak spots. There’s more involved with efficient pedaling than just pushing downward with a lot of force. I’ve identified three points of your pedal stroke where you can gain energy output: Pushing forward over the top, pulling back at the bottom, and lifting the weight of your leg as it moves back up to the top during the ‘backstroke.’ Cycling isn’t a natural motion that we’ve repeated every day since childhood, like walking is for running. Try to develop this pedaling power flow as I’ve described; it will be worth the effort. Without any extra work to increase aerobic capacity you can gain speed by perfecting your pedaling technique.
Figure 1. The difference in the leverage potential of the right crank arm with pedaling force applied from two different directions (clockwise crank rotation).
These examples are leading up to a thorough analysis of how to push in powerful circles with your legs. Figure 1 examines the critical range of motion over the top of the pedal stroke. This particular point of the pedal stroke can be either a powerless ‘dead spot,’ or an extra bonus bit of energy with a little technique work. The challenge is to push your foot forward over the very top of the stroke, and then continue the forward pressure as you begin your down stroke. Figure 1 illustrates the optimal direction of force (A) and the more typical, yet less effective direction of force (B). Figure 1 also shows the amount of leverage available with the average Pedal stroke (B), and the more efficient technique A). The diagonal line (A) which runs parallel to the crank arm represents the effective length of the lever when the pressure is applied perpendicular to the crank. The two lower lines (A) and (B) compare the difference of the effective lever length when the power is applied from direction (A) or (B). Notice that pushing from angle (B) directs about one third of the energy to pushing the crank arm toward the bottom bracket. This is similar to pushing the crank straight downward when it’s at the 12 o’clock position. Direct downward force at the fulcrum (bottom bracket axle) contributes nothing to the turning or torque movement necessary to pull on the chain at the chain-rings, which in turn pulls on the sprockets at the back wheel. Therefore, with an equal amount of muscular power available, pushing only downward (B) can generate only two-thirds the force that is possible by pushing both forward and down simultaneously (A). In the weight room, the leg extension machine, (not the leg press) which focuses on pushing your lower leg forward from the knee, works well to develop this particular muscle action by developing your vastus-medialus (inner quad just above the knee).
But how can you develop your pedal stroke to improve this part of your stroke without going to the weight room? The most obvious is simply to get a feel for forward pressure at this part of the pedal stroke while sitting on your bike in a static position. To get a good feel for this while moving, try the pedaling with one leg drill. To do this, just click one foot out of the pedal and push forward, down, pull back and lift up on the “back stroke” with only one leg. Apply some resistance like light braking or do the drill on a slight uphill in a low gear, and try to feel an even pressure all the way around in a smooth circular motion. If your pedaling motion with one leg is jerky, or worse still, if there are points where your freewheel is not engaged at all, keep working on it. These “dead spots” where you apply no power are clearly the weak spots in your pedal stroke; you can become more efficient and therefore faster by getting a feel for where you could apply more power.
Here is another obvious reason to refine your pedaling technique. As you pedal, your leg must move from the bottom-most position, back up to the upper-most position at the top of the pedal stroke with each rotation of the cranks. Let’s call this upward motion the “backstroke” or “recovery.” Now let’s assume each of your legs weighs 15 pounds. If you generate absolutely no lifting energy with that recovery leg, then you’re using up 15 pounds of your downward force from your quadriceps of the opposite leg to push that recovery leg back up. What a waste of energy! The hip flexor is the muscle that can lift your leg up during this pedaling recovery or backstroke. It is a relatively weak muscle, but well developed in runners, and quite capable of lifting the full weight of your leg repeatedly, thus nullifying the energy loss of pushing your leg back up at each rotation.
So I’ve talked about the possibility of increasing efficiency and power by pushing forward over the top of the pedal, stroke, and lifting the weight of your leg on the recovery or backstroke, but there’s one more crucial point of the circle where we can generate energy output. This is the range of motion between points (4) and (6) on Figure 2. At this point of the pedaling action we can use our well-developed runners’ hamstring muscles. I know many of you with cleated bike shoes already utilize this part of the pedal stroke to your advantage. This motion should be the second most powerful part of the stroke when you get it right, after the dominant downward push from your quadriceps muscle group. The sensation of pulling backwards from an extended leg should feel like scraping something off the bottom of your shoe.
Figure 2. Optimal foot angle relative to lower leg at various points in the pedal stroke as viewed from the right side (clockwise rotation).
Figure 2 illustrates an idealized pedal stroke with the best possible angle of your feet relative to your lower leg to generate the most power around the circle. You might say, “I just watched a bike race on TV and the pro racers didn’t pedal that way.” If you watch closely though, you will see that the slower their cadence, the more they drop their heel (flatten the angle of their foot relative to the ground) over the top of the pedal stroke. Typically when you’re spinning (pedaling fast with little resistance) you don’t need to generate much power and your foot favors the least possible movement at the ankle, thus maintaining a perpendicular angle to your lower leg. But as you pedal more slowly, perhaps needing more power for a climb or to push through a headwind, modifying the angle of your foot at various points of the pedal stroke can increase your power. Here’s why it helps at the top of the stroke: The power that your dominant quadriceps muscle can generate increases as your leg straightens. This can be demonstrated by experimenting with the amount knee flexion versus max weight lifted on a leg press machine. So, you already know a longer crank arm can give more leverage, but on the other hand, the less you bend your knee the more powerful your push. Obviously, this is a bit of a conflict on a bike, due to the large circle created by each crank rotation. When you understand these two limitations, it follows that if you can pedal with a straighter leg you should be able to apply more power at the crank arm. The only way to do this is to bend your knee less, which can only be accomplished by your knee rising less at the top of the pedal stroke. Dropping your heel, keeping your foot flatter relative to the ground over the top of the pedal stroke is the way to do this. You can see this change in pedal stroke in comparing spinning with low pressure, then on the saddle while climbing hard at low cadence. The difference between the heel high or heel low position over the top is small but it can help you develop more power when you need it. This even applies during the current trend toward spinning; even Lance changes his stroke when more wattage is needed for short periods.
Take a look at Figure 2 from point (2) to point (5). Over this range of the circle the angle of foot to lower leg changes, from flexed (flatter) to extended (pointed slightly downward). This is the only range of the pedal stroke where the calf muscle gets to contribute some force by contracting. But, take note though, that this extra energy contribution can’t happen if your foot is already pointing slightly downward at points (2) and (3). So, from these last two paragraphs, we’ve learned of two reasons that the angle of our foot to lower leg is critical to pedaling efficiency. This flexion at the ankle requires moderate flexibility of the joint but I’ve never seen a runner who doesn’t have the ability to do this on the bike. I should also say that in some old school cycling manuals this technique is called “ankling,” and requires much time a patience to develop. Of course you could ride 600-mile weeks like pro bike racers and the proper pedal stroke will probably come naturally by necessity!
Each range of the pedal stroke contributes a different amount of force with inherent muscle strength limitations. I estimate that the forward push over the top contributes about 10%, the down stroke about 65% (including the small calf push near the bottom), and the pull back about 25%. Even though the muscles are working to lift the weight of the leg, the lifting action on the recovery probably contributes little or nothing for most cyclists on a flat road. But when standing on the pedals (while out of the saddle), sprinting/accelerating, or at low rpm on a climb, the hip flexors and hamstrings should supply a significant amount of temporary power. A significant amount of force can be generated by pulling up for short periods, but only when you really need it.
So far I’ve mentioned the term “spinning” with only a brief description when in fact, to develop a smooth spin should be a prerequisite. I’ve left spinning for last because it’s recommended that you do the bulk of your spin work during the off-season base mileage building period. Most bike racers who started young had to race with a gear restriction early on. The reason is to develop a proper pedaling action, and to save young tendons and joints from the stress of over gearing. Spinning is useful because the unusually fast rate of muscle contraction teaches your neurological system to send each muscle stimulating electrical signal at exactly the correct moment. In order for each of these intricate pushing, pulling, and lifting operations to take place a very specific muscle(s) must contract and then relax. It’s not uncommon for the “uneducated leg” to have opposing muscles contracting at the same time, and this is very inefficient. Spinning is defined as a cadence of greater than 95 rpm, and typically less than 120 rpm on the road. Most bike racers can spin smoothly with no bounce on the saddle to significantly over 120 rpm. The best way to develop your spin is to self-impose a gear restriction for a certain stretch of road. Be patient, because spinning takes time to master. Easy, or ‘active recovery’ are ideal days to practice spinning in-season.
To get the most out of your cycling, you need to analyze your pedal stroke and identify the weak spots. There’s more involved with efficient pedaling than just pushing downward with a lot of force. I’ve identified three points of your pedal stroke where you can gain energy output: Pushing forward over the top, pulling back at the bottom, and lifting the weight of your leg as it moves back up to the top during the ‘backstroke.’ Cycling isn’t a natural motion that we’ve repeated every day since childhood. Try to develop this pedaling power flow as I’ve described; it will be worth the effort. Without any extra work to increase aerobic capacity you can gain speed by perfecting your pedaling technique.
