Bicycle Fit – What You Need to Know

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This section of our site is dedicated to articles that can help you understand bicycle fit better and to help you sort through the options so that you can select the best possible fitter and system.Selecting a bicycle fit is different from selecting many products in that it is in no way a commodity.  When it comes to selecting a bike that fits and works properly for you, who you work with is often far more important than what you actually buy.  Skill levels and qualifications vary immensely between fitters and the industry offers little in the form of test based certification. Like selecting a doctor, attorney or contractor, interview your fitter carefully before committing.

View a video that describes the steps of a professional bike fitting

Common Fitting Systems and Techniques

measurement

Measurement Based Formulaic Fittings

These systems rely on body measurements that are plugged into a formula. The formula then calculates a recommended riding position or frame size.

Pros: Simple. Cheap. Requires little equipment or knowledge on the fitters part.
Cons: The most basic type of “fit”. Limited number of potentially important variables considered. Treats everyone similar. Not dynamic – doesn’t actually assess the rider on the bike. Inconsistent end result. Can be biased towards manufacturer.
Examples: Almost all On-Line Retailers, LeMond Method, Some Fit Kit Fitters, Some Wobble-Naught Fitters, Cyfac System, many bike manufacturer sponsored fit systems, Accufit, Bio-Racer.

laser scanning

Laser Scanning

These systems are often similar to measurement based systems, but use a laser scan of the body to take measurements instead of manual tools. Like the measurement based systems, the measurements are placed into a formula which results in a bike size and set-up recommendation.

Pros: “Wow!” technology factor. Simple. Not fitter dependent (very little training of the fitter required).
Cons: Limited number of potentially important variables considered; often relies on a single variable (skeletal measurements) that is of arguable importance to positioning. Treats everyone similar. Not dynamic – usually does not actually assess the rider on the bike. Inconsistent end result.
Examples: Body Scan CRM (used by many bike shops).

dynamic

Dynamic Fitting

These systems usually include elements of measurement based systems, but also include additional physical assessments and consider the rider on the bike. The goal is to make the fitting as similar to actual cycling as possible. A Size Cycle or other adjustable dynamic tool will often be involved.

Pros: When used properly, accurate and realistic. Comprehensive. Individual specific.
Cons: Very fitter dependent (some are better than others). High level of fitter training required. Time intensive.
Examples: SICI/Serotta Fitters, Waterford, some Fit Kit fitters, some other manufacturer based systems.

motion

Motion Analysis/Capture Fitting

These systems are broken down into 2D and 3D categories and are usually advanced versions of a dynamic fitting. The motion analysis/capture system allows the fitter to capture and analyze the rider at specific moments during riding and thus gain greater insight into the details of the motion. The goal is to enhance the accuracy of the dynamic fitting session.

Pros: When used properly, can be the most accurate and realistic fit currently available. Very detail oriented and individual specific. Exceptional documentation potential.
Cons: Very fitter dependent (some technicians understand how to use their tools better than others). High level of fitter training/knowledge required to maximize the results. Time intensive. Some fitters may depend on the technology to determine the position at the expense of communicating with the rider. Equipment intensive.
Examples: Motion analysis/capture systems include: Dartfish, Dialed in Motion, Retul, MAC and Vicon. These companies all produce fitting analysis tools and are not bicycle fitting systems on their own. It is up to the individual fitter to use the tools in conjunction with a dynamic fitting protocol.
Learn more about how Fit Werx uses motion capture and analysis in our fittings.

Recommendations: Whether manual or computerized, formula based fittings are inconsistent and limited at best as they fail to actually assess the individual rider’s needs comprehensively and thus skip key variables (like you actually riding…).  For these reasons, we do not recommend any formula based systems. For example, those that depend on body measurements or body angles on the bike as their sole means of positioning. Dynamic fitting is the most reliable method currently available and, with the right fitter, a dynamic motion analyis fitting will be the most comprehensive fitting you can get.Regardless of the methodology used, it is up to the fitter to actually use the tools and methodology available to its potential. All the fit technology in the world can’t buy a good fit. Scrutinize your prospective fitter, their protocols and their credentials to make sure you know what you are getting. The more comprehensive the fitting, the more knowledgeable the fitter, and the better the communication between the fitter and the rider, the better and more reliable the end result.
Find more information on what steps and knowledge to look for in a dynamic fitting.

Associated Tech Articles on Bicycle Fit:

General:

Aero Position Specific:

Cleat and Leg Alignment:

Fit Formulas:

Frame Geometry and Fit:

Saddle Issues:

 

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