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. First looking at climbing, as all cyclists would like to climb better, then we will discuss spending time on the drops.
We know that as the cranks go through the vertical and the foot is passing forwards, the quads are the only muscle group able to make any significant contribution. At this point, efficient quads are essential to achieving a smooth continuous pedaling 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. 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. Knee Angle 80.4°
Many cyclists find that by sitting up with their hands on the bar tops and a few mm back on the saddle, climbing becomes easier. It is often though that sitting up makes it easier to breath. This may be the case but 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 5-10% more power at this point in the stroke. Sitting up will also put a small positive stretch into the the Hip flexors and one of the quads.
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.
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. Some people climb out the saddle all the time, others never. Anecdotally, cyclists who never get out the saddle tend to be quite tall with relatively short cranks and large minimum knee angles. They don't get out the saddle that often because they don't need to open up their minimum knee angles. Frequently getting out the saddle is often a sign that your cranks are too long for you.
On the Drops
Some cyclists never use the drops, which is a real shame as there can be considerable benefits in doing so. one significant 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 further benefit is that the pelvis is rotated forwards, positively stretching the glutes and improving the leverage at their attachment point. This also shortens the hip flexors and one of the quads, reducing their efficiency, but this is less important on faster flatter sections. Being on the drops will also lower your centre of gravity, improving bike handling. Modern brake hood designs permit lever actuation from either the hood or drop positions, but the leverage available on the drops is significantly higher. What may require a significant pull on the brake levers on the hoods will be a light touch with one finger on the drops. Maybe less important on short shallow downhills, but long 'Alpine' type descents can create considerable hand fatigue if not braking from the drops.
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