If you’ve ever spent time in a local bike shop, you’ve heard the salesmen, repair techs and riders talk about getting the perfect “fit”; talk to a cycling or triathlon coach and they can wax all day and night about optimal hip and knee angles. But what does that mean for you? What exactly is a bike fit? As a weekend warrior or casual rider the main concerns should be comfort, injury prevention and efficiency. Getting those extra 5 watts from a more aggressive posture, well, let’s save that for later.
It turns out a few sessions with a good fitter can accomplish quite a bit more than just turning you into a speed demon. Many of today’s fit systems are built primarily around rider comfort, and for good reason. Most people fall within a very narrow range of body types, so when when it comes to fitting, tweaking just a few crucial components means the difference between a comfortable day in the saddle and walking around like a hunchback. Seatpost height, cockpit length, stem length and height are some of the basic measurements. Changing each of these affects the angles of your joints, and in turn affect how your body interacts with the bike.
Those coaches who had you worried about exactly where your knee extends for a perfect pedal stroke? They’re on to something. Your body type may not fit the so-called “perfect” fit for every biomechanical angle (don’t worry, even the pros don’t often fit, and some of them don’t even come within a close range of accepted norms), but with a relatively painless analysis of your riding style, you can prevent injury, find a comfort zone for long rides, and even develop more power for those nasty climbs on your Saturday group ride. We’ve broken down five of the most popular fit systems and algorithms you might run across in your search for the perfect bike.
The Lemond Measurement
The most basic fitting measurement, popularized by Tour de France winner Greg Lemond, is the “Lemond measurement”. It’s a simple calculation based on your true inseam. To find it, stand barefoot against a wall with a book snug between your legs like a bike saddle would be. Mark the height of the book and measure it. Your Lemond measurement is your inseam (in cm) multiplied by .883. The result is the ideal distance between the saddle and the center of the bottom bracket (and hence the ideal riding position), measuring along the seat tube. Many shops use this measurement, and the accompanying data from Greg Lemond’s Complete Book of Bicycling as an excellent starting point toward getting the right fit. While most of the modern fit systems don’t rely solely on Lemond measurements anymore, it provides a good basis for sizing when you find yourself itching to go bike shopping.
Best Cycle Fitting Program For Triathletes: The Fit Institute, Slowtwitch (F.I.S.T.) has put together not only an exhaustive list of bike measurements, but also the optimized angles that a rider must have for the best performance. If you’re interested in the credentials behind their methods, just check out the CV of Slowtwitch’s founder, Dan Empfield. After competing in the very first Ironman held on Hawaii’s Big Island in 1981 (prior to that the race was held on Waikiki Beach on Oahu) Empfield went on to design the first triathlon wetsuits and some of the most successful aerodynamic bikes ever when he founded Quintana Roo. His design hallmarks — namely, building a bike around the needs of performance athletes — are the foundation of every triathlon and time trial bike on the market today.
Using an adjustable eXit Fit Bike, a certified F.I.S.T. fitter will move your saddle position, the length of the cockpit, and even the drop of your handlebars to measure your comfort level against established norms for different angles of your knees, hips, shoulders, and elbows. You may be near the ideal on one but more comfortable deviating somewhat in other biomechanical measurements — and that’s perfectly fine. The end of result of a F.I.S.T. fit will be a chart with your personalized ideals. From there it’s a simple search to find a bike that has geometry that most closely matches your body.
Retul 3D Motion Capture
Best All-Around Cycle Fit System: Founded in 2007 by a group of biomechanical engineers (who also happened to be some world-class cyclists) the Retul motion capture fit system has quickly become a leader with pro teams and amateur riders alike. The program is similar to F.I.S.T. in that the rider spends time on an adjustable fit bike, but here similarities end. While the rider pedals the Muve Fit Bike, the fitter places sensors on the rider’s body for a 3D motion capture and analysis. Using Retul’s software, changes to rider posture, seat height, and cockpit length provide real time feedback. This dynamic analysis provides insight into body motion throughout your pedal stroke that may not otherwise be captured — especially minute deviations such as rotating your knees or shoulders in a way that may cause injury in the future. It is important to work with an experienced fitter, as the software can only compute the pre-programmed optimal angles, which may not be in your comfort zone. As with any fit, comfort should always trump the scientific ideal.
Specialized Body Geometry
Best Cycle Fitting System On Your Bike: The Specialized Body Geometry program grew from the brand’s experience with many professional athletes in triathlon and road cycling. More than a few world champions have spent time with Dr. Andy Pruitt in their never-ending quest to be faster, and his methodology is the core of the system. Rather than finding a bike to fit you, the Body Geometry program focuses on developing a better relationship with your current bike.
Before riders even get on their bike, Specialized’s system takes into account past riding experience and injuries and takes stock of overall flexibility and strength. Once riders are in the saddle, static measurements are taken at critical joints (knees, ankles, hips, shoulders and elbows) to get a picture of riding style. From there, a fitter makes adjustments and tests several riding positions for comfort level and overall positioning. A one-week follow-up with the fitter allows concerns and issues to be revisited. If you’re already in a love affair with your current bike but want to fine-tune everything from pedal cleat alignment to the angle your handlebars sit, a Body Geometry bike fit should be first on your list.
Body Scanning CRM
Best Simple Cycle Fit System: Sure, there’s a technological “wow” factor, but the Body Scanning CRM laser scan system is decidedly helpful in finding basic bike sizing. Utilizing a large scanner, the system quickly assesses all the different measurements for a rider while they simply stand in the machine. The accompanying software tool takes care of the requisite calculations for seat height, top tube length, handlebar positioning and other major adjustments. A word of caution, though: while this system is an excellent basic size finder, it does not take into account any dynamic measurements on an actual bike. It is still important to ensure that your bike is fit properly for comfort after a body scan so that you don’t walk out of the shop with a bike that will be giving you numb toes or back aches twenty miles in to a ride.
The Guru Experience
Best Cycle Fit System For The Serious Athlete: Design teams at Cannondale and Guru cycles took the Dan Empfield’s F.I.S.T. system principles and began redesigning their bikes around these basic measurements. They took it a step further, though, when they built a computer and custom fitting software into their fitting bikes to add complete computer integration for real-time analysis. After your fitter takes a few basic measurements and gets you up on the bike, each adjustment to different angles or distances is instantly measured by the bike and accompanying laser sensors.
We particularly liked the integration of a power meter in the fitting process; you can actually see the corresponding changes in your power output with even tiny adjustments in positioning. Getting every ounce of power no longer depends on your ability to suffer through a race sitting on the nose of your saddle for an aggressive stance (seriously, next time you’re at a triathlon check out the pros and how they “sit” on their bikes). After a session with the bike and fitter, the Guru computer system takes care of bike recommendations for you — and even lists the changes needed to each bike in order to reach your personalized measurements. If you need to find a bike that will turn you into a human-powered missile, this is it.