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Temporary riding positions.

Very few cyclists will adopt a single riding position for all of their time on the bike. At the very least people will regularly change their hand positions and generally shuffle about to ease pressure points. This section aims to explore some of the more usual postural changes that people adopt when cycling.


Knee angle

Hill Climbing

We know that just after TDC, the quads are the only muscle group able to make any significant contribution and as such are essential to achieving a smooth continuous pedalling action. The knee angle at this position will be around 75°-80° and from the Knee extension graph in the Muscle Activation section we can see that this is in a relatively ‘weak’ area. Extrapolating the graph gives us this relationship, which shows that even small changes to the knee angle can alter its capability to generate torque. Although pedal forces in this region may be small they will be almost perpendicular to the crank and relatively efficient at generating positive torque.

Seated riding, normal ankle position.

Seated riding, normal ankle position. Knee angle 77.9°

Taking this as a starting point, this is the knee angle at the position described as Point 3 on the muscle activation page for a 1.75m tall rider using 170mm cranks.

Sitting back on the saddle

Sitting back on the saddle. Knee Angle 80.4°

By sitting back on the saddle the knee angle will increase by a couple of degrees. This may seem small but we can also see from the Knee Angle graph that this could give 10% more power at this point in the stroke.

Sitting back and dropping the heel

Sitting back on the saddle and dropping the heel / Ankling Knee Angle 82.1°

Some cyclists intentionally drop the heel on the upstroke whilst climbing. This has the same effect as sitting back and will open up the knee angles. If used on a permanent basis the cyclist will need to plantar-flex (point the toe down) around the bottom half of the stroke or the saddle will be need to be dropped, negating the benefit. This process, known as ankling can be effective but needs some practice.

Out of the saddle.

Out of the saddle. Knee Angle 88.8°

The knee angle opens up even further and the cyclist can also pull down with the arms to put even more force into the pedals.

On The drops

On The drops

The primary benefit of being on the drops is to reduce your frontal area. This is especially important on faster sections as aerodynamic drag is proportional to frontal area and a factor of speed squared. A secondary benefit of being on the drops is that the pelvis is rotated forwards, stretching the glutes and hamstrings. This also shortens the hip flexors and one of the quads, reducing their efficiency, but a consistent pedalling action is less important on the faster flatter sections. Being on the drops demands good back and hip flexibility. In many people the action of leaning forwards and rotating the pelvis, lifts the hips and opens up the knee maximum angle.You will note the knee angle on the drops is 144.8°, whereas on the hoods it is 143.4° The saddle height might need to accommodate this depending upon the amount of time spent between hoods and drops.



 

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Page Last Updated : 5th December 2014 All Rights Reserved. BikeDynamics - Bike Fitting Specialists