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Retul 3D bike fitting

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

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Bike Fitting Booking

frequently asked questions

Your bike fit questions answered. If you don't see the answer to your question on this page please CONTACT US.

1. What defines a good bike fit?

In our view, a good bike fit tailors the bike, equipment and riding position to best suit the rider's body type, race or performance goals, flexibility and injury history. The aim of every fit is to provide the rider with a position on their bike that is stable, comfortable, powerful, aerodynamic (where necessary) and reduces the risk of injury. For triathlon and duathlon competitors post bike run performance must also be taken into consideration.

No two fits are ever the same, because no two bike fit clients are the same.

2. Do I need a bike fit?

The answer is 'probably'. There are very few riders that would not benefit from an accurate bike fit in some way. Whether you're an elite level athlete looking at improving race day performance or a new and inexperienced rider looking to improve comfort or reduce injury risk an accurate bike fit can help. Just because a rider is not getting injured does not mean their bike position is optimal. Many of the worlds highest level pro riders turn to Retul certified bike fitting experts to tune their positions and gain every last second on the bike.


3. When are bike fitting bookings available?

Level 1, 2 and 3 are available at Yellow Jersey Cycles at different times, please check the booking section above for current availability.


4. What should I bring with me?

  • Your bike

  • Clip on tri bars - If you're being fitted for a tri position on a road bike, remember your clip on bars

  • Cycling shorts

  • Cycling Jersey (preferably sleeveless for Retul fits as it helps with accurate positioning of the measurement LED's)

  • Clipless cycling shoes

  • Clipless pedals (we cannot complete a Retul fit without clipless pedals)


5. What's the difference between your levels of fit?

Retul is the only dynamic measurement tool that offers sub millimeter levels of accuracy and our Retul fitter is Retul certified, having been trained by one of the most respected, knowledgeable and experienced bike fitters.


Level 1 - the basic Retul 3D dynamic bike fit uses Retul 3D motion capture technology. The Level 1 fit offers a cheaper alternative with the assessment of position, review of cleat position and re-setting the bike as necessary to achieve an ideal position.


Level 2 - the most popular and all round bike fit uses Retul 3D motion capture technology to take measurements directly from the rider while they're riding under a realistic load on the bike. Every aspect of the rider motion is considered - rider strength and flexibility, seat bone measurement and saddle sizing, cleat position, knee movement - all contact points on the bike are adjusted as necessary. A full report is completed including images of before and after, final position angles achieved and full measurements of the bike post fitting.


Level 3 - the same process as the Level 2 fitting, but applies to 1 rider with 2 types of bike (cheaper than booking two separate sessions).


6. What does it cost?

Level 1 - £100

Level 2 - £150

Level 3 - £275 (same rider, 2 different bikes)


7. Will it make me faster?

In the short term an accurate bike fit may not make you faster. It will however make you more comfortable and put you in a riding position where you have the most potential to achieve your optimum results. Over the long term you should see performance gains from an accurate and suitable fit.


8. Do I have to be buying a bike to get a fit from you?

No. We're happy to fit you on any type or brand of bike, whether it be a road bike, gravel bike, time trial or triathlon bike. Riders of all disciplines and performance levels from novice to world class will benefit from an accurate bike fit.


9. How do I book?

Please use our booking links above to make you booking. You will be asked to pay a deposit of £25 against each booking. If you have any questions regarding booking or fitting, please CONTACT US

Retul 3D Bike Fit

WHAT our customers SAY

Bike fitting

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.

Bike fitting

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.

Bike fitting

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.

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