Bike Fit with Marvin
Recently we were joined by Marvin from In The Loop Kiteboarding in clinic for a Bike Fit. This year, Marvin has decided to take up triathlon, with his main goal being Sunshine Coast 70.3 in late August this year. As Marvin has only just begun triathlon, he made the decision to invest in himself and come and get a bike fit at TPM. Following a full biomechanical assessment, we found the following:
- A leg length difference of approximately ~6mm, which is often not significant enough to alter. However, when watching Marvin pedal he was overly raised through his left side when riding, meaning that his functional leg length difference outweighed his anatomical leg length difference. As a result, we installed spacers under his right cleat
- Marvin’s left hip flexor was extremely tight, which was causing him some discomfort during riding. Him and his coach made the conscious decision to change him to shorter cranks a few weeks ago, which will pay off for him in the long run
- While Marvin had fantastic hamstring length from his history of professional kiteboarding, he was quite neurally wound up, meaning that he had difficulty dropping his heel when riding, impacting his power output
- Marvin was getting some elbow pain when resting on the elbow pads on his TT bike
Working as a health professional we have the luxury of treating these issues prior to fitting Marvin in his new position. While we can change a person’s bike position and say “this is the ideal position”, is this really the ideal position for their body type? After treating Marvin, he was able to drop his heel better, felt less pain in his left hip flexor, and as a result, could rotate his pelvis forward to flatten his back out (as seen in the second picture below).
Marvin pre-bike fit:
Marvin post-bike fit:
- Improved hip closed angle: this allows Marvin to be able to run off the bike more effectively, as his hip flexors aren’t closed up, putting more stress on his lower back
- Seat height increased: this reduced patellofemoral (knee) joint load. It will be further increased as Marvin works on his hamstring length in his take-home exercise program
- Front end length increased: this will help with Marvin as he tries to rotate his pelvis forward and place less load on his lower back
- Front end height increased: previously, Marvin had to reach for his bars, causing the “harbour bridge” effect through his mid-back. By increasing the height in the front, Marvin is able to extend more through his thoracic spine and take less load through his elbows, which he noted was giving him issues. This also means that his neck is in a better position, which he will have to hold for 90kms
- Take home program: we are looking to work on freeing Marvin up neurally in his lower limbs, allowing him to drop his heel more comfortably when riding, and helping him to therefore put out more power in a time-trial position
- Leg length difference: Marvin had a functional leg length difference when watching him ride on the bike. We could notice his left side was raised and had a higher power output when looking through the Computrainer system. As a result, we placed a small spacer under his cleat on the right side to even out his power output and efficiency, along with correcting postural imbalances
- By working on Marvin’s position in the aforementioned ways, we have not only made him more comfortable and increased his power output, but we have also reduced his frontal drag area meaning that he is able to be more aerodynamic and save precious time over the 90km bike course on the Sunshine Coast
After finishing Marvin’s bike fit, we finished off his report for his local bike shop to make his alterations. In this report, we included his home exercise program, which worked on all of these imbalances we identified earlier. Marvin will be coming back in in 4-6 weeks after trialling his new fit and we will make any further changes as required. Ideally, if Marvin performs his home program as required, we will be able to lift his seat height a bit further.
Connor McKay – Physiotherapist at TPM
