Bike Fitting

why bike fitting?

Every rider is unique in respect to flexibility, biomechanics and riding style. There are few standard assumptions that apply when truly fitting a rider to a bike. The Yellow Jersey Cycles bike fit studio uses Retül 3D motion-capture technology that allows the capture of less than 1mm accurate data taken from key body points in real time. This data is then utilised to provide the most comfortable and efficient position to maximise performance. 

Retul is the most advanced bicycle fitting system available today.


The system incorporates incredibly precise 3D motion capture technology, immediate reports, and a millimeter-specific digitising tool to provide the most accurate dynamic fitting solution in the industry. Retul is the official bike fit technology for many of the top pro cycling teams...

Bike fits must be dynamic

Most bike fitters fit riders in a static position. This is because the traditional tools of the trade — tape measures, goniometers and plumb bobs — don’t allow accurate measurements while the rider is pedalling. Retül captures the rider’s position relative to his pedalling motion, and therefore creates the most realistic replication of the actual pedal stroke and body position when out on the road and trails. 

Whether you are fitted on your own bike or using the Muve Cycle jig, your biomechanics are analysed using the Retül system. Adjustments to the contact points of the rider can be made regardless of using the Muve or your own bike. By scanning the finished position with the ‘Zin’ tool those contact points can be accurately determined and applied to either your own bike, or sizes and set ups can be recommended based on the collected data. This cannot be accurately achieved using standard equipment as it is impossible to accurately measure the stack and reach of a frame by any other method which is the key accepted method of sizing a TT bike and increasingly more often road bikes.

Measurements must be accurate

Measurements made by traditional tools have one thing in common: they are subject to human error and therefore can be inaccurate. Even slight inaccuracies can completely change the rider’s feel after a ride. Retül uses motion capture technology that is accurate to within less than a millimetre, creating true objective data, which can be utilised by our fitter for the perfect biomechanical fit. Retül will always compare left and right for side-to-side differences. As a certified fitter, we ensure accurate placement of electrodes and therefore the most accurate data, knowledgeable interpretation of data and assessment of physical asymmetries and contributing mechanical issues that can create undesirable ranges. 

Biomechanics are best assessed in 3-Dimensional space

Fit data collected in a traditional 2-dimensional plane (i.e. video based systems) is fairly limited because the fitter can only look at one view at a time and those views stand as independent reference points. In order to make the best fit recommendations, the fitter must realise that the front and side view are actually interdependent reference points. In other words, the front and side view must be viewed simultaneously in 3-D in order to see how all the applicable movements of the body are working together. Retül is also the only system that captures and records this data for analysis.

A bike fit using Retül technology typically includes the following steps:

  • The fitter conducts an initial physical assessment of the rider, and at this point can address the rider's concerns about performance, pain, or any other issues the rider hopes to alleviate during the bike fit.

  • LED markers are strategically placed on eight anatomical points of the rider: the wrist, elbow, shoulder, hip, knee, ankle, heel, and toe.

  • As the rider pedals, Retül's sensor bar gathers real-time, three-dimensional data of the rider's pedal strokes and movements.

  • Retül's rotating platform allows the fitter to collect data for both sides of the rider without the rider leaving the bike.

  • The rider's data is compiled into a reader-friendly report for analysis by the fitter. The fitter can then assess the rider's position and make necessary adjustments.

  • The Zin, Retül's handheld digitizer, allows the fitter to digitally measure the rider's bike at 13-15 points, depending on the bike. The Zin can measure fixed points, contours, and curves, and provides a complete digital map of the bike.

  • The fit information is saved and stored on our fitter's database.

  • The data includes the rider's personal profile, measurements from the fit, bike measurements, and the rider's final fit position.

  • The fitter will be able to access and print these records for comparison and tracking of historical fit data for the client.

For more information, watch this film about Retul 3D Dymanic Analysis Bike Fitting from BRITISH CYCLING


stuart mulchinock

Went for 3D Retul bike fit yesterday! Being a novice rider thought this was essential and the service and knowledge was 5* . Nathan was first class he talked me through the fit and gave me advice on other aspects of set up and maintenance! Worth a visit.

geoff turpin

The results have been remarkable. The following Saturday I did a Charity ride of 104 miles. The lower back pain I had suffered pre the bike fit was non existent. The pins and needles I had been getting, in my fingers, after 10-12 miles have been greatly reduced in severity and don’t develop until much later into a longer ride. 
I would thoroughly recommend your bike fit service and attention to detail.

richard price

Many thanks for such a meticulous service with the bike fit. I took both the TT and race bike straight to Hog Hill for 2hr test ride, not only did i feel more powerful, they're more comfortable too. Despite the large adjustments I've had no difficulties with cramp or stiffness - thanks again.