Efficiency

A single pedal revolution involves a downstroke-power phase and an upstroke-recovery phase with each leg. The downstroke phase delivers most of the force that generates forward momentum whilst the upstroke phase unloads the weight of the leg on the pedal and keeps the cranks rotating.

Pedalling is the movement of the legs in a circular motion to transfer muscular power to the pedals of a bike, in order to move the bike forward.

Pedalling effectively involves using the balls of the feet, keeping a constant speed and pedaling in a circular motion. A good general cadence [r/m] rate is 80-100 rpm although depending on the circumstances cadence can vary from 50 to 200 rpm.
 
A relaxed flowing style is more economical and maximizes energy use. In the early stages of learning to pedal it is best to develop efficient pedalling technique at a relatively high cadence with the focus on spinning. However the Wattbike can be used for high cadence low wattage at one extreme and low cadence high wattage at the other. 
 
On a bike, with the exception of gravity, the forces assisting speed are mainly produced by the force that is applied to the pedals. This is not simply a case of the size of the forces being applied, if a rider stands up briefly onto a horizontal crank a relatively large force will be produced, but will do little to propel the bike forward.
 
To propel a bike forward successfully a rider must continue to apply force as the crank rotates; the forward propulsion of the bike is dependent upon the force applied and the distance over which it is applied. This is known as the work the rider does to the pedals. This tells us only how far the bike will move. If a rider pedals 10 times at a particular resistance (gear) the bike will travel the same distance per revolution whether they are turned at 50 r/m or 100 r/m but the rate at which they travel will be different.
 
Applying large forces to the cranks will not necessarily lead to forward propulsion of the bike. For example, if a downward force is applied to the cranks while the cranks are in a horizontal position (3 o’clock) this will act to turn the cranks and propel the bike forward.
 
If a downward force is applied when the cranks are at the vertical position (6 o’clock) the force cannot act to turn the cranks and will not propel the bike forward regardless of the size of the force.
In practice some of the force applied to the cranks does not act to turn the cranks. Most of the force is applied in a relatively small area of the crank cycle around the 3’ o’clock position when the crank is horizontal on the downstroke.
 
A rider may pull the pedal upward during the upstroke to unload the weight of the leg on the pedal and keep the crank rotating rather than creating a forward propulsive force.
 
Achieving optimal efficiency is not simply a case of applying all of the force at right angles to the cranks, as this does not take account of gravity or momentum.
 
The force curve on a Wattbike shows the peak force profile of the left and right leg downstroke:
  • the left hand side is the left leg downstroke starting at the top of the graph (12 o’clock position) and finishing at the bottom of the graph (6 o’clock position)
  • the right hand side is the right leg downstroke starting at the bottom of the graph (6 o’clock position) and finishing at the top of the graph (12 o’clock position)
Whilst the ideal force curve is yet to be determined a number of shapes show the effectiveness of applying force as the crank rotates to maintain momentum and minimise the ‘dead spots’ at the top and bottom of each pedal revolution (the force curve reducing to zero at the centre of the graph).
 
Riders should imagine ‘scrapping mud off the sole of the foot’ at the bottom of the pedal stroke to ensure a smooth continuous pedalling action.
 
The shape of the force curve may be different for different types of cyclists and events i.e. sprint and endurance.
 
The shape of each force curve usually has a diagonal lean with peak force achieved beyond the 90Ëš (3 o’clock horizontal position). The angle of peak force will vary from individual to individual but should be at the same angle in each leg.
 
Ten top tips to improving your cycling efficiency.
Set Up your Wattbike Correctly
  1. As a first step check your cycling position – incorrect cycling position can affect both the downstroke and upstroke phases.
  2. Irrespective of your force curve make sure you are applying force to the pedals evenly with each leg. The left/right leg % should be as close to 50/50 as possible (it will fluctuate but try to keep in the range 48%-52%).
  3. Consider investing in a good pair of cycling shoes. The use of training shoes will, generally always compromise your force curve as they make it difficult to fully implement the full power and recovery phases.
  4. To practice pedalling don’t stand up on the pedals unless it is a specific session you need to do. It will produce a relatively large force but compromises the ability to apply force as the crank rotates.
  5. A ‘figure of eight’ shape may indicate too high a resistance setting forcing you to concentrate solely on the downstroke – power phase preventing upstroke momentum. Lower the resistance to a level which allows you to improve you force curve to optimum. Concentrate on ‘scrapping the mud off the sole of the foot’ to at the bottom of the pedal revolution.
  6. However note that the Wattbike can be used for high cadence low wattage at one extreme and low cadence (r/m) high wattage at the other. Optimum leg speed is important. Experiment with different cadences and resistance settings. Cadence range can vary from 50-200 depending on the type of cycling you do.
  7. Set the Wattbike Performance Computer to display the Polar Graph when you do a workout. You can set the text view you want on the right hand side of the display by pressing the ENTER button. This will constantly remind you to focus on effective pedalling.
  8. If you have a laptop set up the Polar view in the Wattbike Expert Software. In addition to showing your force curve you can also see your angle of peak force and set the display bar at the bottom of the screen to show all the left and right leg parameters:
  9. 9. Set yourself a specific cycling effectiveness workout where you concentrate solely on improving your pedalling action and force curve rather than on distance, speed, watts, HR etc. Split the workout into short intervals and gradually expand the time of each interval as you improve.

    For example: 
    5 x 4 minutes – 1 minute rest between each interval 
    4 x 5 minutes – 1 minute rest between each interval 
    2 x 10 minutes – 1 minute rest between each interval 

    Then try a 20 minute session holding the force curve for 20 minutes
  10. And finally practice, practice, practice