- Neuroplasticity, Habituation and the CPG.
- Cycling pains
- Preferential fatigue
- The importance of cleat position
- Seat height and setback
- Cycling articles for bike fitters
- The cyclist’s tricky hip, part 1
- The Cyclists’s tricky hip – part 2
- Part 3, the assymetrical hip socket rider
The feet are the single most important piece of the bike fit puzzle. Through your feet you transfer power to the pedals as well as receiving feedback via your nervous system as to the movement and load being generated. Any decrease in the ability of the feet to effectively transfer power will result in some type of compensatory response – this can vary from imperceptible feelings of “vagueness” on the pedal through to severe biomechanical problems extending up the kinetic chain into the knee and hips.
Human beings have evolved over thousands of years to walk and run. Cycling a bicycle is a very unnatural movement which differs from walking and running in a number of ways. The most major difference is the lack of impact of course. Unfortunately, impact is a vital part of the walking and running cycle – as we strike the ground with our heel or forefoot, it causes a sudden response in our lower leg musculature which causes these muscles to switch on. This is called a “tendon stretch reflex” and forms a large part of how our body times and co-ordinates reciprocal patterns of movement such as walking and running. When we get on a bike, there is no impact and so these stretch responses never get initiated.
Longer and shorter Titanium Speedplay axles for altering the foot separation distance of the rider.
The implications of this vary from person to person depending on how much their central nervous system relies on the stretch response, but the overall problem is the same – the muscles which usually switch on to support our rearfoot and arch remain electrically silent and relaxed when we cycle. This means that the arch and rear of the foot has a MUCH greater tendency to drop and flatten when we cycle compared to when we walk or run.
Again, the individual variation between people is huge, and this is where foot correction comes in to play. A dropping arch or a varus tilt in your rearfoot will almost always lead to your knee being forced in closer to the top tube of the bike. The movement pattern can be a steady angulation in from the top of the stroke, or a marked ovality in the plane of the knee’s movement, or even a sudden violent “twist” at the bottom of the stroke as the calf disengages from the “push” phase and releases its control of your heel. The end result is always the same – cycle for long enough, and hard enough, and you will develop some type of problem from this – the first result is usually some type of knee pain.
When correcting the feet, we use Archtech G8 insoles with adjustable arch support and a solid heel counter to begin with. They are a well designed piece of gear which work perfectly for cycling. Almost every cyclist will require these modules. Despite Specialized offering shoes with in-built varus wedging, I am yet to see a pair of cycling shoes which have any meaningful arch support inside. This is a major oversight by the various shoe manufacturers as, unfortunately, the implications are not widely known.
We start by determining the level of arch support required, then incrementally adjust the tilt of your rearfoot (heel) and, less commonly, your forefoot to seat the foot most firmly on the pedal and keep your knees moving perfectly in the same plane as the crank arm. In combination with Steve Hogg’s heel wedges, we use cleat wedging on the bottom of your shoe to cant the entire foot if that is what is required – this process is extremely detailed and requires a level of finesse and experience on the part of the bike fitter.
Foot problems on the bike range from hotspots, numb toes and the like through to cramping in the arch, Achilles pain and so on. The culprit in these circumstances is usually cleat position, seat height, shoe size or improper foot correction. It is impossible to list the possible causes and effects of such pains and annoyances as they are many and vary drastically between cyclists. In almost all cases these problems are fixable with a proper bike fit and well-matched shoes with good foot correction inside.
Often the area that receives the most attention from cyclists and bike fitters alike is the knee. Knee pain manifests in many different ways on the bike, and traumatic injuries aside the issues are always overuse. That is to say that the pain increases gradually over one or more rides and is only relieved once off the bike. If the damage that the problem causes is great enough, the pain can carry over to your off-bike life as well.
Knee pain falls into two main categories;
1. Pain arising from over or under-extension of the knee. Usually this is frontal or posterior knee pain, often the precursor is hamstring or quadriceps tightness and fatigue which then becomes a serious pain as the load of cycling continues through your ride. The painful structures are usually your patellar tendon (the large, triangular tendon connecting your kneecap to your lower leg) or the structures underneath it, and the hamstring insertions on the back of the knee. Less common is the origin tendons of the calf muscle which arise from just above your knee on the posterior aspect.
Most commonly these issues begin with a seat that is too high. For many years bike fitters have been using goniometers (joint measuring devices) and motion-capture software to measure the knee angles. You will commonly hear bike fitters and websites expousing rhetoric such as “the included knee angle at maximum extension must be between 142 and 148 degrees and at minimum extension………… and so on”. These measurements are “rules of thumb” are, as a general rule, largely useless for most cyclists. If you have particularly inflexible hamstrings, gluteals or a stiff lumbar spine for example, these “rules” will often result in you developing knee pain if the bike is setup in this manner.
I have a deep mistrust for any angle measurements of the knee being used as a guideline for seat height and/or setback and will never use such a narrow-minded view of the function of a person. Often the end result of such a fit is a seat that is too high. Any increase in seat height above optimum WILL result in some sort of instability on-saddle, which naturally carries down through the kinetic chain into the leg. Knee pain, hamstring issues and gluteal pain is often the result. I regularly see riders who have been fitted with the aid of computerised systems or motion capture software who are sitting up to 60mm too high. Yours truly was one of these riders many years ago, and severe right sided knee pain was the result. In my case, a well-known computerised fit system followed months later by a “professional” fit both put my seat height around 60mm too high. This is simply inexcusable for a paid service and, whilst the extremity of my case is unusual, the general pattern is not – most riders sit too high, and knee pain is often the result.
2. The other main category of knee pain is lateral or medial knee pains (on the inside or outside of your leg). These are more tricky and have a multitude of potential causes. Overwhelmingly, the direct cause of the knee pain is that the knee is trying to track in a different plane of motion to the arm of the crank. The knee is a simple hinge joint which is only reliably able to function if it is moving in the correct plane of movement. Any deviation of the knee in terms of torsional movement (twisting) or ovality in the tracking of the knee will result in excessive loading of the lateral structures (the Iliotibial Band or “ITB” is a common culprit) or, less commonly, the medial structures of the knee. Often pain will feel dull and “behind the kneecap” – this is a sure sign that the patella, the large bone in the front of your knee which acts as a force couple for the quadriceps musculature, is being pulled forcibly out of its natural vertical plane of motion on the front of the femur.
Long-term abuse of the patella tracking will result in the thin lining of cartilage on the back face being worn down steadily until osteo-arthritis (bone on bone) is the end result. Patellar mal-tracking is the most common of the knee pains that we see and can be caused by many different issues – almost all of which are either above or below the knee itself. Tight external rotators in the hip, tight and overactive hip flexors, weak medial quadriceps, a collapsing arch, improper cleat placement, too high or low a seat, or incorrect foot correction (rearfoot AND forefoot) can all play a part in forcing the knee to track in the wrong plane of motion.
Here is a rider showing a small right side bias by dropping his right hip and rolling it forwards. Notice that the hip does not rebound fully back to horizontal. The rider will often present with LEFT ITB and knee pain.
Most commonly we will see riders with left knee pain. This is usually a result of a right sided problem. Steve Hogg has written an excellent and well-informed article about what he and I call the “Right Side Bias”, you can find it HERE. It seems to be significantly more common to find a rider who drops and rolls the right hip than the left. Steve and I have postulated many different possible causes for this, but whatever the cause, it is a fact that a right side bias appears to be a lot more common than a left side bias. The consequent drop and roll of the right hip creates a “lift and tilt” of the left hip. This challenges the plane of motion of the left knee and seems to particularly irritate the ITB, leading to lateral pain or patellar maltracking. The issue is often resolved once the cause of the right hip drop is removed and the left knee is once more tracking cleanly.
Lower back pain is another common complaint on the bike. In a positional sense, the most frequent cause is too much seat setback or incorrect seat height. Having your bars too far away and having to “reach” forwards beyond your capabilities to stabilise the resulting position can create this issue as well. Another more complex and difficult to pick issue is poor on-bike stability which can have a multitude of causes – not all of them positional.
Here you can see a gentleman who is young, fit and strong with no obvious signs of instability off the bike, but who functions as you can see here. This is an extreme example of poor on-seat stability but is by no means the worst we’ve ever seen. It is easy to see how this fellow developed his back pain on the bike! Some good core strengthening work off the bike will usually moderate this “rock and roll” style over time, leading to happier backs and knees on the bike.
Unilateral lower back pain, structural injury aside, is usually caused by excessive dropping and rotating of one of your hips. Most commonly the right side hip will drop excessively and roll forwards during the downstroke, this can create right sided lumbar pain from excessive lateral flexion or, in some, left sided lower lumbar pain due to the repeated compressive forces acting on the left side. The same can be said about a left hip drop creating conversely orientated pains.
Neck pain is more simple and is usually caused by a lack of necessary functional extension in the neck whilst in the cycling position. We can alter the circumstances around which we develop neck pain by either increasing the capability of our necks to extend easily (which requires a lot of off-bike flexibility work) or by altering the position such that your neck and shoulders are sitting in a more natural, unloaded position. Thankfully, most neck pains are muscular in origin and there is often no damage associated with them, just muscular discomfort.
Shortening up the reach to your bars via a shorter stem, or lifting the stem further up the steering tube is the most common improvement we will make to lessen this problem. Bearing too much weight via your upper body and arms can cause neck and upper back pain as well, rather than forcing the neck into end of range extension. Correcting your seat setback and reach to the bars is important not only to unload the upper body musculature from a pain perspective, but by disengaging these muscles you will free up bloodflow and oxygen delivery to be pushed towards the more important areas – your legs.
LLD’s are a complicated and tricky area of the bike fitting experience. There are two types of leg length difference – structural and functional. The two are explained below;
1. Structural LLD’s are relatively simple – during our growth spurts in our teenage years, often one of the tibial bones (the large, long bone below your knee to the foot) or the femur (large leg bone above the knee to the hip) or occasionally even the calcaneum (heel bone) will grow slightly quicker than the other. The reasons are unclear but the most logical explanation is usually a slight difference in the degree of vascular delivery to the growth plates in the bones. In other words, one of the bones has more blood flow and hence it grows more quickly. The end result is that at some point when you stop growing, you may end up with a LLD which can range from imperceptible to vast. A few days ago in our clinic we were visited by a young lady who has a 15mm LLD. She is a high-level compensator and had never known about the issue aside from having right sided lower back pain on the bike. Others will struggle with a 4mm discrepancy causing marked knee or back pain – such is the variety of human function.
To the left is the author’s full-length leg Xray films taken to determine any structural LLD. We are able to refer the client off for these films as required under a Medicare rebate.
Other reasons for structural LLD’s can vary wildly – fractures, hip disease, joint replacements – the list is virtually endless. In cycling terms, the result is always the same – the rider will compensate for their LLD in some manner which forces a certain amount of asymmetry into their stroke. The compensation responses are as individual and widespread as their potential causes – a dropping hip on the shorter leg, a dropping hip on the LONGER leg, a pointed toe on the shorter leg….. the list goes on forever. In order to function as symmetrically as possible when cycling, the LLD needs to be compensated for. This is where shims and shim stacks come into play. Shim stacks sit between the sole of your shoe and the cleat and effectively lengthen your leg. A shim stack of the correct length is selected for riders with LLD’s to create the highest level of functional symmetry possible. Below you can see a small shim stack of 4mm underneath a Speedplay cleat.
2. Functional LLD’s
A functional LLD is what occurs when a rider presents with neurological, structural or muscular insufficiencies which prevent one leg from extending as easily, quickly or with as much control as the other. The causes, again, are myriad. A tight hamstring, a stiff sacro-iliac joint, a tight gluteal, a stiff ankle, a marked dominance of control of one side of your body – the list goes on. The end result is an asymmetry of function on the bike which is often much harder to pick than a structural LLD. They are also usually harder to fix. If you have a functional LLD which presents on the bike, I will find the cause and recommend that you remedy this to achieve the best possible functional symmetry. A common presentation, for example, is an inflexible hamstring complex on one side from, say, an old tear in the region. I will endeavour to set your bike up as perfectly as possible to achieve functional symmetry, then recommend that you go and do something about your hamstring tightness – either visit a good health professional or perform a targeted self-treatment regime on the area over some weeks to months. If, for example, I have added a 3mm shim stack to your functionally shorter leg, you should be able to remove the shim stack once the function in the hamstring returns to normal.