Pedal pedal pedal
Cadence continues to be one of the most discussed topics in cycling. New riders often worry about gear selection and interestingly, often start out with a high gear and lower cadence as they try and focus on developing more power by working harder.
Coaches will spend time teaching new cyclists how to pedal because they know the right gear selection has a huge impact upon a rider’s performance and their enjoyment of the sport. This article will provide a brief introduction into what is a pretty complex topic.
Muscle Physiology
To understand the importance of gear selection we have to understand the different muscle fibre types and their different metabolic and recruitment properties. Broadly there are two types of fibre: fast and slow twitch. Anaerobic fast twitch muscles are recruited by the nervous system for powerful movements, for example pushing off from a standing start in a 1km track time trail. While they are capable of producing lots of power, they fatigue very quickly. Slow twitch muscle fibres are aerobic and resistant to fatigue making them ideal for propelling you along a 100km sportive, but their tension and force production are low by comparison. When we ride a bike we don’t make a conscious decision regarding which muscle fibre type we are going to recruit, but our choice of gearing has a major impact.
A little bit of physics!
If we want to move the bike we need to apply a force via the leg muscles thought the feet and pedals to rotate the crank. When a force is applied over a distance (rotation of the crank) we can say that work is done. Now, that work can be completed slowly or quickly and the faster we do it the greater the power output, which is measured in Watts.
A bike with gearing gives the cyclist a choice of how they generate power: either by using a low gear and applying less force, but over a greater number of crank rotations, or by using a high gear and applying greater force over fewer crank rotations. In other words the same power output can be achieved using two very different pedalling strategies.
If we now think about the muscle physiology described above it becomes obvious that different muscle fibres are going to be employed depending upon the strategy. Low cadence/high gear/high force strategy will use the less fatigue resistant fast twitch fibres, whereas the high cadence/low gear/low force strategy will favour the more fatigue resistant slow twitch fibres.
The benefit to the sportive rider of using lower gears is that they can place all the energetic demand upon the more fatigue resistant aerobic slow twitch fibres that use fuel sources such as fat. For the racer, hiding in the bunch and soft pedalling in a low gear prior to reaching a steep climb or sprint finish means that they can conserve the freshness of their explosive fast twitch fibres for the decisive moment of the race.
Implications for Training
The key metabolic implications of gear selection have been described above, but there are other factors that affect these decisions such as muscle blood flow, efficiency, tactics, choice of crank length and aerodynamics. Future articles will address a number of these topics in greater detail to help build a wider range of understanding.
The human body has an incredible capacity to adapt to the demands placed upon it during training. If you choose to train in a high gear then your brain and the neuromuscular system adapts to that style of cycling and it becomes difficult to ride in any other way. To ensure riders can shift between different physiological needs efficiently, it is advised to actively train using a range of cadences. This can be low cadence hill repetitions at 40-60 revolutions per minute (RPM), long ‘supple’ rides at 90-100 rpm, or full gas sprints greater than 150 rpm.
By including a range of cadences in training, both fast twitch and slow twitch muscle fibres are trained and the nervous system adapts to better coordinate muscle contractions at a range of leg speeds. One tried and tested way of achieving this, and a great excuse to start looking for a new bike, is to purchase a fixed wheeler for the winter. The big advantage of a fixie is that with only a single gear and a direct drive you are forced to ride the full range of pedalling speeds or risk ending up in a heap on the road!
