Bike Fit Principles
Talking about principles isn't the sexiest thing in the world, I know. But they're important in bike fitting no matter who you are....no really! Any athlete can apply these principles as a checklist when they go in for a bike fit -- if your fitter doesn't adhere to these ideas in words or in actions then there's a good chance your bike fit won't be as effective as it could be. As a bike fitter or PT just trying to learn more about bike fitting, these principles can guide your educational process to make sure your attention and resources are put in the best places.So here we go, some of the basic ideas that are critical to understand for an optimal bike fitting:
Bike Fit = Body-centric
Bike fit has much less to do with the bike -- it is absolutely body-centric. This isn't to say that understanding the bike isn't important, but the amount of information you need to understand about bikes is dwarfed by what you need to know about the body and how it moves.The more you can understand about how the human body moves and functions, the further ahead you'll be.
What you don't do is important
It's really easy to make changes to someone's fit. Anyone can decide to raise a saddle or rotate a cleat, but having a clear rationale behind the changes is critical. As a bike fitter's understanding of the rider's mechanics improves they'll get to a point where they'll have to make critical decisions about not changing something.This can translate into only making three changes when there are four you were considering. That fourth change may be to much for the rider to absorb right off the bat.It can also mean changing something, but not past a critical degree. Knowning when to stop is key. Sure, a rider may benefit from a 1 cm raise in their handlebar position, but that doesn't mean 1.75 cm is going to be even better.You have to know when enough is enough. The only way to get there is to have a database of thousands of movement assessments and bike fits to draw on for help.
If you can't measure it, you can't fix it
This is a tough one but it's something I came to terms with long ago. When I purchased an expensive infrared motion capture system about 10 years ago, my eyes were opened. At the time I was performing very adequate bike fits with the best analog methods available at the time. While I didn't have fancy technology, I did have my background as a PT still and I was able to reason through some very complex clients and solve many of their problems. My first days with the infrared system quickly made me realize how much I was missing. It was showing me movements I would have no hope of ever seeing with my eye or use of alignment lasers. Further, things I thought I was seeing one way proved to be moving very differently than I ever thought.The same sort of epiphany happened when I started using saddle pressure technology. I began to see seating patterns in such a new way that it made me realize how much I didn't know before simply because I could "see" or measure it.A good bike fit can still be done with analog methods, but in order to solve the tough problems you need to be able to quantify what you're looking at.
Balance correction vs. compensation
Compensation: making changes to the bikeCorrection: making changes to the bodyThese two definitions are a bit simplistic of course, because some bike changes are not compensating for any imbalance, they're just aimed at trying to put a joint in it's most efficient range. But as a generalization we can think of bike changes as compensations trying to make up for imbalances that we have in our bodies, while off the bike exercises and treatments can be thought of as "corrective" trying to fix the imbalance that we have so we can fit our bike better.Most bike fitters rely solely on bike changes, or compensations because most have limited training in corrective exercises. The bike fitter that also has a background in assessing and correcting human movement has a distinct advantage. To most movement problems, the best solutions have both corrections and compensations, and similarly, the best bike fits have both bike changes and recommendations for corrective exercises. Attacking these problems from both ends has the greatest chance of success.The bike changes can allow the athlete to ride their bike safely and efficiently right now, which can help maintain the rider's motivation and fitness level, while specific 0ff-the-bike exercises can help to move them toward more neutral movement patterns in an ever evolving effort to fit their bike better.In truth, there are some bike changes that can even be therapeutic -- one interesting one that I've used a few times is placing a leg length shim (even in the absence of a shorter or longer leg) under the cleat of the leg that has difficulty neurmuscularly firing properly. The shim provides a slightly easier reach to the pedal which enables the body as a whole to feel that side more and induce that leg to engage more. I have had many cases where this shim is placed, the rider begins to sit more squarely on their saddle, the leg gets in the game more and over the course of a few months more symmetry is achieved and the shim can be removed. It's a safe bet that every athlete has some imbalance they can work on -- exercises can always play a role in bike fitting.
Off-the-bike assessment is required
There are many bike fit training classes that don't teach any off-the-bike assessments or if they do, they're very basic and are never really applied to the bike fit itself. It's as if they did it to check the box off on the list of "To-Dos" but never put the information to use.If you don't have at least a basic understanding of where the client moves well and where they don't, you can't hope to make fit decisions with any accuracy or effectiveness:A knee can drift out to the side for a lot of reasons -- the saddle could be too low and there's nowhere for it to go, foot mechanics can drive it out, the rider could have a retroverted hip, or osteoarthritis on the anterior rim of the acetabulum, their cleat could be improperly rotated....I could go on and on. I'll say it again:If you don't understand how the athlete moves, you can't fix their problems on the bike.
What principles can you think of? Let me know what you'd include -- comment below or reach out to me.