Cycling Biomechanics
Article by Jon Roberts
Director, Matt Roberts Personal Training
January 2012
How to Cycle Better
The diagram below perfectly demonstrates the muscular sequence of events that should happen in the correct cycling pedal turn.
It clearly shows how right at the top phase of the pedal strike the power should come straight on via the glutes, the muscles of the bottom, and power down to a point where the very big and strong quadriceps muscles share the power and then gradually become the dominant mover in the sequence.
During the lower section of this very powerful movement the calf muscles join the quadriceps to push the pedal through the lowest section of the pedal turn. It is then the turn of the muscles of the shin to pull the toes back up to level the foot out and the hamstrings muscles to bring in a powerful pull back up. The final stage of the movement is the muscles of the hip Flexors pulling the knee back up to the start phase.
When a cyclist cycles with this sharing of power there is much greater ability to create higher wattage, power, on the bike by not having any dead spots of power during the cycle rotation. It also means that there is greater use of all muscles and no overuse of one muscle group which helps prevent injury and muscle overuse issues.
The most common problems that we see with cyclists of all levels are:
1) Overuse of the quadriceps. Most people who cycle tend to rely too much on the big muscles of the quadriceps as a result the ability to create power is diminished. As the diagram clearly shows, if you rely on your quadriceps for all power at best you have 90 degrees of movement that are useful to you. Leaving 270 degrees of underperformance. Learning to get a feel for using all muscles will immediately bring greater speed with no more effort.
2) Lack of power on the lift phase. Power of one degree or another comes in to play at all phases and the use of the back phase of the pedal strike is essential for both greater efficiency but even more importantly to prepare for the new power phase. The more powerfully you bring the foot back up to the top phase of movement the more likely you are to be ready to apply the power down first through the glutes and then into the quads. Training the hamstrings and the hip Flexors to be able to perform this task is essential if you are to maximise all phases of movement.
3) Tight muscles across hips and hip Flexors. As most of us spend too much time seated and not enough time increasing our mobility and flexibility tight hips and hip flexors are a very common issue that we see. From a cycling point of view what this tends to result in is a lack of ability to efficiently bring the knee to the top phase of movement without having to compensate through the upper body. This is commonly seen when you watch a cyclist from behind and see their back swaying from side to side with every pedal lift. This happens as the body makes room for the knee to be lifted through. However, put a great deal of stress on the spine and the muscles of the lower back.
Good range of movement and strength through the hips allows for good knee lift through the top end of pedal phase and power to go straight on, with the body holding tight and allowing maximum power transfer through the pedals. Lack of adequate range here also tends to result in repeated lower back tightness and pain.
4) Toes pointing down. If you watch cyclists you will see a vast number who cycle with the toes lower than the heels at all phases of movement. This style of rising will often be partnered with the body being positioned to far forward so that the knee can get over the pedal. This toe pointing style of riding makes it very difficult to use the glutes effectively in the first phase of movement and also makes it much harder to bring the knee back over the top phase of movement at the end of the pedal movement and be ready for starting the next phase of movement.
5) Knee alignment over toes. During all phases of cycle movement, when you watch from the front, the knee alignment should be almost directly above the line of the toes at all times. This is particularly important at the top and power phase of movement. This alignment during power phase allows all power that the cyclist generates to be transferred down through the leg and into the pedal. If this alignment is out the power will not be directed down into the pedal, therefore losing power, and also the added lateral movement through the body will add strain into the joints of the knee, ankles and pressure across the foot.
Analysing your pedal use is essential to make sure that you maximise performance and also prevent injury. Think about the way you cycle and which muscles are being used at what phase. You can also look at analysis like the Apex Performance Testing that is offered through Matt Roberts Personal Training.
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