Bike Fit, Part II

I changed out the photo from the bike fit, part 1 blog.  I originally couldn't find my 2003 IM Brazil bike pic, which was my first ironman.  I finally found it and posted.  Take a look and compare to above.  Kind of fun.

***

On to the next step in the evolution of my bike fit. During my time in Boulder, I scheduled a bike fit with the guru at the Boulder Center for Sports Medicine, Andy Pruitt. He, along with Todd Carpenter ran me through their program.

After filling out a basic intake questionnaire, we discussed if I was interested in a performance or problem oriented fit. A performance fit would concentrate on improving power output through position changes. A rough estimate of the aerodynamic profile could be performed as well. The most aerodynamic position in which maximal power output can be obtained is eventually sought. Although comfort is not the primary outcome in this sort of fit, the position must be sustainable for the given distance. If the position is not sustainable, then a less aerodynamic position is used until it can be maintained for the race condition. This position should be measured in a real life situation and compared to the prior position.

In a problem oriented fit, a thorough biomechanical assessment is performed to determine underlying pathology. A physical exam was performed by a frontal and back coronal view to determine obvious pelvic obliquity and truncal imbalance. Flexibility was examined to determine any areas that might prevent a position otherwise prescribed a particular formula (more to come on next post). This included an exam of my neck, back, and lower extremities (hip flexor/hamstrings/ankles). A thorough physical exam, including a strength evaluation, was completed.

I chose the performance fit, as I had been able to ride my current position in a few ironmen with reasonable success (5:09 IM Brazil bike split).

We then headed in to the bike fit studio where my bike was already set up on the trainer by Todd Carpenter. Todd had studied at the Univ. of Colorado and had done some interesting work on aero position vs uncompromised comfort position on the effect of TT performance. In a nutshell, comfort wins.

I completed a baseline power exam on my the position I presented with (top picture). Then we applied the motion monitor markers (little glow balls on my body) and recorded kinematic data. Using this data, we made some adjustments in fit to gain the correct angles and range of motion during the spinning cycle. Adjustments were also made to my cleats to address knee tilt and avoid loss of power generation by movements that were not driving the leg directly into the pedal (tibia straight up and down like a piston as opposed to elliptical motion).

Though I was interested in improving performance, the changes we made were to improve comfort (bottom pic). I raised my handlebars in order to allow the upper back to reduce the amount of cervical lordosis required to look up the road. This, and the cleat positioning, composed the majority of change. We tested the second position with a similar power test, which resulted in a lower heart rate average for the same power output.

All in all, this was a great experience. It confirmed the fit I had tinkered on since my fit with David Greenfield was pretty good. The additions of cleat adjustment was great fine tuning. The biggest take home was that comfort, even for performance, nearly always trumps "intuitive" aero changes. My one disappointment was the inability to test different positions that might have increased power output, in addition to making the one position I had more economical. I may be splitting hairs and there may not be any difference. As you will see in part 3, I think you can take the comfort caveat and still have room for additional power improvements.