What is Retül?

What to expect:

Retul Harness

  • Our Chartered Physiotherapist will assess your range joint motion, flexibility and individual biomechanics
  • On your bike we will perform a detailed analysis of your on bike position and movement from both sides
  • Any required changes will then be made
  • The analysis will then be repeated to assess the effectiveness of the changes
  • The ‘Zin’ too is then employed to accurately record the exact dimensions of  your bike (see the ‘Zin’ in action)
  • A final report is prepared and provided to you so you can apply this to other bikes.
  • Expect this to take about 2 to 2 1/2 hours.


Why use Fit-Me-Up:

  • The knowledge and experience of the Chartered Physiotherapist will help to explain your own physical needs and be able to listen to your individual issues
  • We employ the use of 3 separate leading edge technologies to provide you with what we believe to be the best synergy to help you achieve your fitness and cycling goals.
    • Retül, for fitting your bike to you.
    • WattBike, for pedalling technique and power assessment.
    • Bikefit for foot/pedal interface assessment.

We are all individuals, with human asymmetries being surprisingly common. Cycle frames are manufactured to very specific parameters for both the ease and the safety of the user. Although this does not necessitate a problem, it can cause issues and reduce the efficiency of the cyclist.

Retül is the system and related technologies that enable us to to adjust the parameters of the cycle to meet your individual requirements, this is the key that Retül offers you to unlock your greater cycling enjoyment and potential.

Using the 3D motion-capture technology in real time, we aim to provide you with the most efficient position on your bike to maximise your potential comfort and performance.


Retül is dynamic, rather than using traditional, static measurements to fit your bike around you the 3D motion-capture technology provides you with live feedback to you technique.

With the use of real time recording technology we are able to make changes and re-assess the efficacy of any changes made. We are also able to monitor the power output gained pre and post-fit, together with the all important feedback from you regarding how you feel on your bike.

The accurate placement of body markers is paramount when utilising this technology and we are pleased to utilise the detailed anatomical knowledge of our Chartered Physiotherapist to place these markers. This takes away the previously accepted margin for error with ‘manual methods’ and increases the understanding of how best to increase your comfort and reduce the risk of injury to you.

With the technology being employed the data generated is more objective than could have been previously achieved, that added to us not selling bikes or frames here ensures you receive the advice that is right for you. We believe that this is key when a new bike or frame can see you investing a great deal.

The 3-Dimensional nature of the technology employed not only reduces the time you are required to spend here with us, it increases the accuracy of any change as it is not just ‘observed’ in a single plane, as when traditional video capture technology is employed. In short, the accuracy of any changes can be immediately assessed by the motion capture system and felt by you.

Your individual biomechanics are accurately assessed and worked with. In conjunction with a history of any injuries you have experienced our fitter will establish the most suitable solution for your needs.

Your report will allow you to use the information gained during your visit to be applied to another bike of the same type, size and similar geometry.

To the fitting session, you will need to bring with you your bicycle, a set of appropriate cycling shoes and a set of shorts and short-sleeved top, this  would ideally be tight fitting to prevent any unwanted movement of the LED markers.

What are your personal cycling related goals?

We will help you achieve these through your fit and if required the use of the WattBike and Bikefit technologies.

Example goals we encounter are:

  • Increased comfort
  • Decreased fatigue
  • Increased speed / power output
  • Injury prevention
  • Rehabilitation from injury*
  • A combination of the above

Whatever your goals let us know and we will work with you, to help you achieve them.

*As a Chartered Physiotherapist Dean is happy to work with your health care professional and is not looking to treat you, rather to complement your treatment and help you through a smooth and hopefully faster return to the level of activity to which you aspire.

Issues addressed by a Bike Fit

Cycling equipment is generally symmetrical and fixed – it is therefore the body that inevitably has to yield and change in respond in the interface process. Asymmetry in our own bodies exacerbates this process. A Retül Bike Fit will take account of these asymmetries and adjust your bike contact points accordingly around you.

Ranges of motion
Particularly around hip/pelvis area and hamstrings – will affect fluidity of your pedalling motion, posture and muscle-recruitment patterns. Posture can affect muscle recruitment, comfort and efficiency, altering your bike around you can enhance your cycling experience.

As the level of your own personal condition can profoundly affect your ability to hold good cycling posture, transmit power and your overall stability of the pelvis as well as protecting the lower back from pain and injury while on your bike, this is another factor we consider.

Utilising a Wattbike analysis we can help build a picture of which muscles are being utilised in different sectors of the pedal-stroke.

Cleat position/foot/arch-shape
Perhaps the most important contact point between you and your bike for power and comfort – In cycling the leg’s kinetic chain is closed by the pelvis/saddle contact at one end and by the shoe/pedal interface at the other. For this reason we ask that you bring your regular cycling shoes with you.

Who should get a Retül Bike Fit?

Anyone who plans to ride a bike for any period of time should consider having their position assessed to ensure optimal efficiency, comfort and injury prevention.

All cyclists, no matter how long they have been riding or their ability, can improve their cycling biomechanics by having a thorough analysis.

All of our customers are free to perform better and enjoy their riding more as a consequence of reviewing their on bike position.

Reasons to consider a Retül Bike Fit

Almost all regular cyclists will enjoy riding their bike. Sometimes this enjoyment can be compromised by niggles such as saddle sores; knee, neck and back pain; or an inability to improve their performance beyond a particular personal best. Many cyclists are forever tinkering with their position – looking for that elusive perfect posture, but unable to pinpoint why they “just don’t feel quite right”.

Common Issues related to improper fit

Patella Shear Forces
A low saddle height will mean that the knee angle is too tight at the top of the stroke. When the cranks are approximately vertical, the quads become the dominant muscle group, effectively pushing the foot over the top. The quads attach onto the tibial tuberosity via a shared tendon that encloses the patella (kneecap). When the quads contract, forces are applied in the direction shown, giving a resultant force pulling the patella against the femur. The shear forces acting at this interface will be dependent upon the efforts being expended and the angle between femur and tibia. As these forces increase, so does the likelihood of tendonitis and harmful stresses in the cartilage behind the kneecap.

Patella Tracking
The forces (F) acting on the patella are primarily along the direction of the femur (due to muscles rectus femoris and the medial and lateral vasti). The groove in which the patella glides is along the vertical dotted line shown here. To prevent the patella scraping against the sides of the femur there needs to be a corrective force applied in the direction shown (Fm), which is the job of vastus medialis. Using electrical recording of muscle activity, we know that vastus mediallis is most active during the later stages of leg extension, presumably due to an evolutionary benefit to walking and running. If the saddle is too low though, there will not be enough leg extension to get the vastus medialis firing adequately, potentially causing patella misalignment in conjunction with the high shear forces noted previously. Over a period of time, and provided the knee pain is not serious enough to prevent riding, the other three quads might strengthen dispropotionally to vastus medialis, making the problem even worse. An added problem is that this muscle is weakened extremely quickly when the knee is injured, often needing specialist training programmes applied to the extended knee.

Cleat Misalignment
A very common cause of knee pain is misalignment of the cleats, causing the foot to be excessively toed in or out. Ideally the foot will be allowed to adopt its natural position with adequate float each side to accommodate any rotation whilst pedalling. If the foot is held in an unnatural posture, the tibia will be rotated, again causing poor patella tracking and unnecessary strains on knee ligaments. If the foot is excessively toed in, this will contribute to the tension in the illiotibial band (ITB) a fibrous connective tissue that runs along the thigh and attaches to the tibia. This band has to cope with the articulation of the knee but can often become inflamed due to friction.

Cranks too Long
If the crank arms are too long for your leg length, the knee joint will be too tight at the top of the stroke and shear forces increased as discussed above. In this case though, the saddle might not be too low, but in the right place to give suitable knee angles at maximum extension.

Saddle Too High
A saddle that is too high is likely to cause problems at the hamstring insertion points and increase tension in the illiotibial band. Two of the three hamstrings attach on the medial (inner) side of the tibia, below and to the rear of the knee joint. The third inserts on the lateral (outer) side of the tibia. If the saddle is too high, the hamstrings will be over-stretched possibly causing tendonitis or bursitis at the attachment points. A tight illiotibial band can cause inflammation where the band crosses the knee joint and contribute to patella misalignment.

Knee Lateral Displacement  –  Fore-foot Varus
Many cyclists have very large lateral movement of their knees and suffer no ill effects at all. Others do suffer discomfort, either a degenerative condition of the joint menisci, or more usually inflammation of knee ligaments, having to work hard to stabilise the joint. A strong inward kick of the knee over the top of the stroke is associated with an unsupported fore-foot varus.

Excessive Dorsiflexion
There is an amazing diversity in what cyclists do with their ankles whilst pedalling. Toes can point up or down and the range of ankle movement between the top and bottom of the stroke can range from -10° to +30°. ‘Normal’ ankle behaviour would be to undergo a small amount of dorsiflexion as the power is applied, followed by approx. 20° of plantarflexion as the leg is fully extended. High levels of ankle dorsiflexion can cause large knee displacements, usually when the cranks are approximately horizontal and loads are at their highest. Under high efforts, the heel may also stay low around the bottom of the stroke, stretching the hamstrings and calf muscles that attach behind the knee. This excessive dorsiflexion is often due to the instep collapsing and can improved by fitting insoles with more arch support.

Vertical Offset
Although bike frames come in a variety of sizes, the width of the pedal spacing across the bike is pretty much the same for everybody. This spacing (often called Q factor) appears to be optimised for average sized gentlemen. Unfortunately, very slim people can find this spacing much wider than their hips, especially if using an even wider triple chainset. As the applied loads from knees to pedals are not vertical, there is a resultant lateral force pushing the knee inboard, causing undesirable stresses at the joint. Similarly, wide hipped people can also suffer, usually from ITB related issues as the feet are held too close together. Although not straightforward, vertically aligning the hip knee and feet can often help resolve knee and foot pain.

Back Pain
Saddle too low
As the foot goes over the top of the stroke, the knee comes up too high and the lower back is pushed backwards, first by one leg, then the other.

Tight Hip Joint
Lack of joint mobility will apply torsional forces to the pelvis as the knee comes up. Although not directly involved in the pedalling action, the hip adductors can often impede effective movement and benefit from regular stretching.

Neck and Shoulder Pain
Neck and shoulder pain is often due to the reach to the bars being too long. To reach the controls, the elbows may need to be locked and the shoulders rolled forwards. The locked elbows will then become far more efficient at transmitting road vibration into the upper body. The long reach will also imply an aggressive torso angle, straining the neck to be able to see forwards.

Attempts to reduce the stretch by moving the saddle forwards can be counterproductive as more weight is then placed on the hands and arms. Raising the bars can help the neck but the best solution is to reduce the stretch with a shorter stem, narrower bars or compact bars with a shorter reach. Ideally the bars will be placed to allow your elbows to be slightly bent with relaxed neck and shoulders.

Saddle Soreness – Hip Rocking
The most frequent cause of saddle soreness is a saddle that is set too high. As saddle height is increased, hamstring flexibility will eventually limit how far the knee can extend, which means either the heel will need to come up or the hip will need to come down.

Ankle flexibility will also have its limits so the hip will need to drop as the foot goes through the bottom of the stroke. The effect of the hips rocking on each pedal stroke is to slide the crotch from side to side over the top of the saddle.

A leg length difference can exacerbate this as the cyclist may subconsciously lean the hip of the shorter leg forwards and down. Some people, as shown left, will sit very asymmetrically even though their leg lengths are identical.

Choice of saddle can be very personal, making it very difficult to make recommendations. Ideally the cyclist’s weight will be on their sit bones rather than the crotch so the width of the saddle can be an important consideration. The crotch is not designed to be weight bearing so excessive pressure can cause numbness and a frequent desire to urinate. In this case, tipping the nose of the saddle down slightly, or choosing one with a hole in it can be an effective solution.

There is a world of difference between a ‘Bike Size’ and a Bike Fit.

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