Thinking about bike-fitting correctively or therapeutically

Considering your own bike position: 

Bike-fitting is not all that sophisticated, even though some understanding of biomechanics and exercise physiology helps. Getting your own position optimized is simpler than you might think because our bodies are much better at self-measuring than we give them credit for being.    Sitting down in an unfamiliar car, adjusting the seat is quick and intuitive. You know when you can’t reach the gas pedal or brake comfortably or safely. Adjusting the rear-view mirror doesn’t take any thought, even though the tiniest angle change is the difference between seeing out the back of the car or not.   You will perform best positioned on the bike within the same natural range of motion that tells you when a car seat is properly adjusted. From a comfort standpoint, the bike position is a version of your driving position rotated forward.

It is also a version of the classic athletic stance, seen in tennis, skiing, baseball, and so forth. Being well-balanced, it allows you to cantilever forward with minimal effort, so you can drape your hands on the handlebars instead of locking your arms as props.  While riding, look down at where your hands rest on the bars. Relax your arms so you see a bend in your elbows. If your hands aren’t quite able to settle in the cradle of the hoods, the distance you see between your hands and the hoods is roughly how much closer the bars should be to support your natural extension. Similarly, if you are frequently scooting yourself back on the saddle, the distance of the scoot shows how far you are out of the natural range of motion, measured from the back!

While riding, unclip one foot and pedal one-legged. If you are not positioned over the cranks naturally, the pedal-stroke will have gaps and will not feel fluid.   Your pedal-stroke is based on your hard-wired motor program for running gait, applied to a fixed-gait system. Simply, your body tries to follow the pattern it uses while you are running. Even if you have never run, you have a natural stride-length, and “footfall” pattern, which makes you a heel-striker, toe-striker, etc. You adjust to the terrain, but you default to that innate program. While pedaling a bike, the body tries to follow that program as well, but is limited by the contact points of saddle and pedals. If your saddle is too high or too far back, the effect is like adding an inch or two to your stride-length while running!  

The crux of getting your position right is trusting your body to guide you. Bike-fitting is a process of finding your optimal position, and then inserting the bike underneath you like a scaffold to hold you in that position.  

The right handlebar:  

The intent is to look for the optimal position of your body as if on its own in space. Once you arrive at that optimal position your equipment selection has to support you there. Your relationship with the handlebars will have the greatest effect on comfort and preventing pain in your lower-back, shoulders, and arms. If the position is too close to the limit of your range of motion, in harder efforts you will end up crossing that limit and will be fighting to maintain your position as much as fighting the conditions.  

Even though bars are typically sized according to shoulder width, more important for your bike fit are the “reach” and “drop” measurements. To support the upper body, the bike’s overall reach is determined by the combination of top-tube length, stem length, and bar reach. If the reach of your bars is off you will feel the same effect as riding a frame that is one or two sizes off!!! Many frame-builders design bikes backwards from the handlebars to be used.  

Of the various ways to shorten or lengthen your reach, correct bar choice accomplishes the most. You can adjust reach with stem length, but the stem doesn’t do anything else for you – it’s just a connector. In contrast, each handlebar has so many unique attributes that actually trying out the feel of different models will allow you to truly customize the feel of the bike. In any bike-fit, you should be able to try 2-4 bar choices, and your reaction to each will tell you which is best.  

First, you want the part of the bar leading to the levers to be flat, so that the levers extend off the bar at a tangent to create a platform. If the bar dips down to meet the lever hood in a little trough, your hands will have to reach down into that to hold the hood, making it very difficult to relax your shoulders and elbows.  

Most of the time, the drops are uncomfortable because they are too deep, or the angle of the bend is too extreme for the hand and wrist. If you can’t reach the drops, don’t blame your own technique or even lack-of-flexibility – it’s just as likely poor handlebar design! You can rotate the bar in the stem so that the bars are comfortable in the drops, but doing so changes the “platform” effect of the tops/hoods above. With a well-considered handlebar, the drops position will give you a sustainable option that is aerodynamically efficient and more stable at speed, without compromising the positions on top where you may spend most of your time.  

Don’t under-estimate the role of your handlebars; it is at least as critical as finding the saddle that fits. 

In response to an email I received:

I’m not exactly sure of your question about the fit-bike. I’ll answer by talking about how the fit-bike assists me in my process. Like you said, the fit-bike is good for figuring out the position for a custom bike, or in lieu of having a bike present. The goal of bike-fitting in general is to find the optimal position of the rider’s body in maximizing efficiency, performance and sustainable comfort, as if the rider were operating on it’s own, and then adjusting the bike or building a new bike to insert it as a support or armature to hold the body in that position. The fit-bike is good at that because it doesn’t really replicate an actual bike and allows you to just look at contact points of bars and saddle etc. without having to worry about changing out stems and seatposts etc. It also gives the data of power and pedal-stroke efficiency variables, based on the resistance on the mag unit in the back, which is also helpful in adding to the mix. 


However, I am more confident in the feedback of the rider, and looking for the fundamentals of range-of-motion and ease of movement in the joints, than following data based on formula. At first I followed a pretty specific protocol using the fit-bike to get really tight numbers, but it ended up being a case of diminishing returns for the time spent, only because my data didn’t lead me to any different outcomes than if I were doing something more fluidly. At the shop where I used to work, I went through many body-measurement sessions with folks ordering Seven frames, getting all the body proportions recorded to the millimeter, which I would submit to Seven for calculation on their end. Then for the sake of the customer I would have a standard fit session talking about what to look for in posture, and pedal-stroke, and core-recruitment (all the stuff we went over), and determine the position based on those characteristics, along with rider feedback, as a cross-reference to the Seven formula….you guessed it, the my fit measurements and Seven’s calculations always came out to within 2 millimeters of each other!  Your position on the bike is like your yoga practice in that your own edge is always changing, and the the bike is just there for neutral support for you to work with dancing around that edge. 


Obviously a poor bike fit is poor because the bike is always asking you to hold something past your edge, which compromises performance, or hurts. Furthermore, the dance is not that precise because the conditions are always changing on a given ride.  Finally, I look at the bike underneath the rider as following two separate templates, doing two separate things: #1) holding the rider in the optimal position, like a scaffold or armature, and #2) providing the ride qualities desired. Theoretically, a bike with a top tube of 53 cm and a handlebar/stem reach of 22 cm will give the same “reach” measurement as a bike with a 56 cm top tube and a bar/stem measurement of 19 cm. Both of those accomplish #1 by supporting the upper body with the same (theoretical) 75 cm of reach. However, looking at the “handling” template, one of those combinations may provide more stability than the other, matched with the right frame geometry (wheelbase, head-tube angle, etc) for the desired effect. The fit bike, for as good as it is at nailing the #1 template, unfortunately can’t address the second template at all! At that point, it’s all up to the custom frame-builder to extrapolate the#2 numbers from the #1 fit template. Or, if  there is already a bike on hand, the bike-fitter can determine based on a general understanding of bike design how to best balance the two templates.  


I could ramble, so I’ll make sure I answer the crank-arm length question. It’s actually it's just about the single most contentious issue in bike-fitting and cycling biomechanics these days. Some research shows lengths as short as 120 mm (way shorter than 170 mm!) to be optimal for riders even as tall as 6’5″, and yet no such length is even available! I spend a lot of time pondering this issue. On my one bike I have 165 mm cranks, and the other 177.5 mm. More than one centimeter’s difference, and yet I ride both bikes on the same day and they both feel natural. Different, but both natural. The same way running stride-length adjusts on different terrain. There is a lot to crank length that is unresolved, but as long as it feels good, it probably is. Certainly, if you wanted to experiment at length on the fit-bike with crank-length it would be very informative, for various reasons. Its relation to the gearing would probably not be relevant since compact gearing is only the equivalent of one rear cog different than the standard 53/39 in terms of gear-inches. However, what the body identifies as easiest through the pedal-stroke will probably always give the best results.