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Review - Retul Bike Fitting
article & images by Nick Salazar
Jun 30, 2010  hits 48,752

Retul offers an unprecedented level of precision to bike fit.

Retul has been generating a lot of buzz in the triathlon and cycling world in the last year or so. They've been recruited to fit the likes of Lance Armstrong, Levi Leipheimer, Chris Lieto, Craig Alexander, Normann Stadler, and many more. Their website shows images of athletes with strange-looking dots and wiring on their body. So we went to Retul's studio in Boulder, Colorado to get fitted ourselves, and see what all the fuss was about.

However, to best describe what Retul does, we should first describe the problem it was meant to solve.

The Evolution of Bike Fitting

A good bike fit is the single most important cycling-related purchase one can make. Without a proper fit, a rider is at greater risk of getting a repetitive-use injury, not to mention sacrificing performance on the bike. There are several systems out there, such as F.I.S.T., which guide a bike fitter in determining the proper position for any given rider. A fitter will observe a rider during the rider's pedal stroke, and measure certain key body angles in order to execute the fit. The problem with these systems has always been taking measurements.

Traditionally, a fitter would either ask a rider to freeze at one point in their pedal stroke, and take measurements using a hand-held tool called a goniometer. The tool is basically a giant protractor, and it works fine, except that it is prone to multiple forms of measurement error. The fitter could easily measure the angle too obtuse or too acute. But more importantly, a rider invariably changes their pedal stroke when tasked to "freeze." The heel tends to drop, and the knee slides back. If the fitter isn't measuring the rider's actual position, then it doesn't matter what fit system is being used; the fit will suffer.

Next came video analysis, which captures footage of the rider pedaling, and instead of asking the rider to freeze, the fitter can simply pause the video. This is definitely an improvement, but still carries with it some possibility for error. Even if the measurements are accurate, the fitter is looking at just one moment in time. One pedal stroke. As any rider knows, your body may shift from one pedal stroke to the next. Who's to say the fitter picked the one frame of video that's representative of your actual riding position?

Enter Retul

What Retul claims to do is nothing short of revolutionary. By placing a set of special markers at key anatomical points on the body, Retul captures the actual, three-dimensional motion of the rider over a length of time, and automatically calculates and averages those biomechanical measurements. Measurement error is all but eliminated (the fitter still has to place those markers at the appropriate points), and by averaging your position over time, the system captures what is your actual, true pedal stroke.

Moreover, Retul goes farther than merely measuring your body position with precision. What they also measure, with stunning accuracy, is your bike. If you plan to keep your current bike for the rest of your life, this is unnecessary. However, if you ever want to buy a new bike, having accurate bike measurements is critical. It'll ensure you purchase a bike that fits you, and it'll help you get it set up properly once you have it.

Of course, all of this sounds great in theory, but how does it actually play out in practice? Read on.


  • The Zin tool takes precise measurements of the bike's contact points.
  • Fine adjustments are often necessary to achieve a precise fit.
  • Mat advises Julie Dibens about proper arm position.
  • The new Speed Concept bikes are stunning from just about every angle.
  • Mat scans Julie's Speed Concept with the Zin tool to make sure her position is perfect to the millimeter.
  • Retul has seen its share of champions, whose pictures adorn the walls of the studio.
  • Julie Dibens has had an extraordinary season this year, and looks to take on the World Championships in October.
  • Retul has plenty of traditional bar and stem options for tweaking a standard bike.
  • Joe Gambles and Trek's Mark Andrews enjoy some laughs between runs.
  • But once he's on the bike, Joe is all business.

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