Bike Fit

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Description - Bike Fit

Bike fitting is process of adjusting a bike for a cyclist to optimize their comfort, performance and efficiency. Cyclists often experience overuse injuries such as cyclist's palsy, cyclist back, and anterior knee pain. and this is often due to an incorrectly set up cycle. Bike fitting aims to prevent injuries, increase efficiency, comfort and improve performance for all cyclists. Bike fitting is for anybody who cycles, particularly if an overuse injury has occurred, to maximise their enjoyment and performance.[1]

Indication

Bike fitting is for anybody who cycles. A good bicycle fit goes a long way to prevent overuse injuries and helps muscles and lungs function at best ability, all improving performance and enjoyment.

  • everyday cyclists
  • touring cyclists
  • tri-atheletes

Clinical Presentation

Cyclist's who complain of: buttock; back; lower limb; upper limb and neck pain associated with cycling.

Often the cyclist may have tried pressure garments to relieve areas of pressure eg gel pads in gloves, gel seat covers, upright handle bars. Often these are a bandaid solution to an incorrectly fitted cycle.

4 Pillars of a cycle fit

1. Foot position

When placing your foot on a flat pedal, the ball of your foot should be just in front of the pedal spindle ie the spindle of the pedal should support the back section of the meaty part of the ball of your foot allowing the rider to stay balanced when standing on the pedals. Having your foot further back on the pedal ie more contact near toe, places the achilles at a disadvantage allowing it to fatigue quicker when standing on pedals and can lead to achilles problems.[2]

2. Saddle height

A very important part of bike fit is the saddle height. A simple way to get your basic seat height is by having your heels over the pedal spindles, your heels should stay in contact with the pedals throughout an entire backpedal stroke. If you lose contact with the pedals, or have to rock your hips to maintain contact, your saddle is too high. Then with foot in cycling position your knee should have a slight bend at the bottom of the pedal stroke.[3] This keeps your knee joint stable and protected.

3. Stem

Some people prefer a more upright position eg. those with back issues, or flexibility issues. This can be addressed by adding a spacer to the stem to bring the handlebars up higher.

4. Handlebar position[4]

A bike fit is about fitting to you so the below guideline are loose to allow for individual anatomical variations. The handlebars should be in a comfortable lean forward position that doesn't strain your back, neck, shoulders or wrists. [5]

Urban 2.5cm. above to 2.5cm. below the level of the top of the saddle
Mountain 5cm. to 10cm. below the top of the saddle
Touring 2.5cm to 5cm below the top of the saddle
Sport/performance 5cm to 10cm below the top of the saddle

A basic bike fit

The video below gives an elementary guide to a bike fit. Specialists exist who exclusively do bike fits ( tri-athletes etc. pay big dollars to have these done) or bike stores may offer bike fits when purchasing a bike.

[6]

Research

A 2017 study into effects of a bike fit on perceptions of pain, comfort and fatigue found that seat height and knee angle had a significant effect of these parameters. The chosen angles were knee flexion angle [20°, 30°, 40°] and trunk flexion angle [35°, 45°, 55°], all positions trialled for 45 minute cycle. The combination of 40° knee flexion and 35° trunk flexion was perceived as the most uncomfortable position, noting that greater knee flexion had a negative effect on trunk comfort, accompanied by greater levels of fatigue and pain perception in the anterior part of the thigh and knee. cyclists perceived the most comfortable position to be when the saddle height was within the recommended knee angle ie 30°and an upright trunk was found to be the most comfortable position for recreational cyclists, where aerodynamics is not so important.[7]

A 2018 conference paper argued that there is no consensus of what parameters to focus on and is hence subject to expert 'subjectivity'. To solve this problem a group in Flanders has now started a research project to develop a methodology to perform automatic bike fitting based on novel data-driven decision-making processes.[8]

Conclusion

Nick Croft, 1991 Australian Triathlete of the year puts the reasoning behind a good bike fit nicely, and it can be expanded to all types of cyclists.

"A fully tricked-out tri bike is useless if your body presents a sail to the wind. At the end of the day triathlon is a non-drafting sport. No matter the terrain, we are always pushing our own way through the wind. Therefore, being aero and comfortable in that position to run well off the bike is crucial."[9]

References

  1. Fit Kit Systems. Glossary of bike fitting terms. Available from: https://fitkitsystems.com/education/training-resources/glossary/ (accessed 21.8.2019)
  2. Diamond Back. Optimal Foot Placement. Available from: https://ride.diamondback.com/optimal-foot-placement ( accessed 21.8.2019)
  3. Diamondback. Setting perfect saddle height. Available from: https://ride.diamondback.com/setting-perfect-saddle-height ( accessed 22.8.2019)
  4. Epic Cycles. Bike Fitting. Available from: http://www.epiccycles.com.au/service/bike-fitting/ (accessed 21.8.2019)
  5. MEC. Fitting your bike. Available from: https://www.mec.ca/en/explore/fitting-your-bike (accessed 22.8.2019)
  6. Art's Cyclery. How to: do a basic bike fit. Available from: https://www.youtube.com/watch?v=VrZBjOloChg (accessed 22.8.2019)
  7. Priego Quesada JI, Pérez-Soriano P, Lucas-Cuevas AG, Salvador Palmer R, Cibrián Ortiz de Anda RM. Effect of bike-fit in the perception of comfort, fatigue and pain. Journal of sports sciences. 2017 Jul 18;35(14):1459-65. (accessed 23.8.2019)
  8. Braeckevelt, Jarich & Verstockt, Steven & Witvrouw​, Erik & Mertens​, Pieter. (2018). Data Driven Bike Fitting. Available from: https://www.researchgate.net/publication/325870002_Data_Driven_Bike_Fitting/citation/download (accessed 23.8.2019)
  9. Baker M. 5 Bike Fit Secrets PDF. Available from: http://www.custombikefit.com/wp-content/uploads/2017/01/5_Bike_Fit_Secrets.pdf?inf_contact_key=ef27637c7c56e72f8c0463985dbd284f (accessed 22.8.2019)