Correct bike set up to avoid injury depends on the bike and its use. Here we concentrate on the optimal position to prevent injury when recreational cycling
1. Get a bike that’s the right size
Check your frame size – stand astride the bike, there should be approximately a 2 inch clearance between the top tube and your groin, increasing to a 3 inch clearance on a mountain bike.
Next check the crank length. There are lots of figures quoted for this, but as a rule of thumb the crank should be 21% of the length of your inside leg measurement.
2. Assess the saddle height
With the pedal in the 6 o’clock position i.e. where it is fully down, the heel of the foot should be able to just rest on the pedal with the knee straight and with the pelvis remaining level. This means that when pedalling the knee will be slightly flexed still at the extreme of the downstroke.
If the saddle is too high
To maintain power at the end of the downstroke the pelvis has to tilt laterally, also causing a side bend at the lumbar spine. This repeated lateral side bend and pelvic tilt can eventually cause sacro-iliac joint (the joint where the spine joins onto the pelvis) and lumbar spine problems.
Having the saddle too high also puts the hamstrings at a mechanical disadvantage at the extreme of the downstroke increasing the risk of hamstring strains.
If the saddle is too low
The knee doesn’t go through as large a range of movement increasing the pressures going through the knee cap and thus increasing the risk of anterior knee pain (pain at the front of the knee).
Additionally, at the top of each stroke the hip comes into a greater degree of flexion increasing the possibility of hip pain, and meaning that the lumbar spine will often give into flexion and thus set up back pain.
3. Look at the saddle tilt
Start off with the saddle horizontal. Put a spirit level on the saddle and adjust until it is level. A forward tilt on the saddle transfers your weight through onto your hands and shoulders. A backwards tilt on the saddle increases the flexion at the lumbar spine and the pressure on the groin.
Whilst low handlebars aid an aerodynamic position, handlebars that are too low in the recreational cyclist increase flexion at the back causing back pain. They also increase weight through the hands and shoulders leading to wrist or shoulder pain, and give a hinge in the neck. This is because you have to tilt your head up to see where you are going resulting in neck pain, sometimes with headache.
An ideal trunk position for the recreational cyclist is 40 – 60 degrees forward from upright which will enable a shoulder position of 80 – 90 degrees flexion.
5. Cleat position
At half way down the downstroke, the kneecap should be directly in line with the centre of the front of the pedal. Looking at it from both the front and the side, adjust this by moving the cleat forwards or backwards and rotating it and by adjusting the fore aft saddle position.
This is a rule of thumb only, people often have feet that naturally point in or out, and the cleat needs to be adjusted accordingly. An incorrect cleat position causes excessive rotation of the tibia on the knee and may cause knee and hamstring problems.
Disclaimer: The information on this page is written as a basic start to understanding bike set up. There are many possible variations for bike set up.Should you have any health concerns regarding a cycling injury you should always seek advice from a qualified health professional or your GP
by Alison Whiteley 10 June 2009