Todd Carver, Cliff Simms, and Franko Vatterott created Retül back in 2007 as a 3D bike fitting system that used markers on the body and a camera to capture — and fine-tune — a rider’s position on the bike. Fast forward to 2022, and the brand that’s been owned by Specialized since 2012 now offers a digitized off-the-bike assessment as well, which practitioners can plug into their on-bike fits.
Carver invited VeloNews in for a fit session to check out what’s new.
I have had a few fits with Carver over the years, as well as with professionals like Ivan O’Gorman who use the Retül system. What I appreciate is the melding of a fitter’s experience with a handy, repeatable system of measurement. Fits usually begin with an assessment of flexibility, preferences, and riding history. Then once on the bike, a fitter works to get various angles within ranges that work for that set of just-established parameters.
Also read: Technical FAQ – Adapting bike fit as you age
What’s new with Retül is a digitized range of parameters customized for the rider. So say you’re young and flexible and eager to race road bikes. There is a set of parameters for hip, back, and knee angles (and much more) for that rider. Or say you’re older with an injured back and looking to ride gravel. There’s a set of parameters for that.
Also new is how measurements are taken off the bike. A digital tool is applied to the lower back to measure and record back angles and flexibility. Foot shape and insole height are captured digitally, as is sit-bone width in the riding position. All this plus flexibility assessments of the hips, back, hamstrings, and feet are taken into account before the rider gets on the bike. Much of this is captured with Apple’s iPad markerless motion capture, which functions similarly to Retül’s original motion capture where markers are affixed to the body at key joints like the knee, ankle, hip, shoulder, elbow, and wrist.
Once on the bike, a fitter puts physical markers on the rider and positions them perpendicular to the Retül camera. There, pedaling mechanics and body angles are captured under pedaling load (Retül uses a smart trainer). Retül also captures mechanics from the front, to see how the knees and hips track relative to the ankles.
Like any tool — albeit a very sophisticated one — the ultimate results with Retül rely on the skill of the user. So Specialized is keen to partner with professional bike fitters who know their craft. However, the detailed list of ranges — like knee or back angle, or knee position over the spindle — establishes some guardrails for what the sweet spot is for any given measurement.
I brought in two test bikes — a road and a gravel bike — and Carver quickly had both machines feeling just like home for me with a few small tweaks. A few weeks before going into Retül, I was on the Fast Talk podcast to talk about ‘buying speed’. Hosts Trevor Connor and Chris Case were asking for my thoughts on gear like aero wheels or helmets. One of my first recommendations, in terms of customer purchase, was to invest in yourself. Getting into a comfortable, efficient, and aerodynamic position represents such a huge piece of the speed and efficiency equation. Going through the latest Retül fit process just reinforced that philosophy for me.
Those who are interested in a Retül fit can use the Retül website to find a certified Retül fitter near them. A Retül fit session can last two-and-a-half to three hours, and a session may cost about $400 (it’s up to the individual fitter to set the exact price).
Retül co-founder Todd Carver walked me through the new fit process, showing where I fell within the suggested ranges Retül created based on a detailed assessment of flexibility, ride history, and cycling goals.
Markers placed on joints for 3D motion capture has been a cornerstone of Retül since created in 2007. Retül has since moved from its own software written on PCs into a Mac- and cloud-friendly format.
The Retül Premium Fit begins with a series of flexibility assessments.
One new tool is this sacrum sensor, which measures angles and flexibility.
How low can you (and your hips) go? This helps determine a good fit on the bike.
Specialized long had an “assometer” that took sit-bone width in mechanical form by sitting on a moldable pad. Now that measurement is captured with a digital pressure map. This is used to ascertain proper saddle width. External hip width and sit-bone width aren’t necessarily related.
The new iPad has motion capture that doesn’t require physical markers. Retül has incorporated this into a portion of the fit process.
But bike fit remains a hands-on affair for fitters; all the knowledge earned through — in Carver’s case — thousands of fits, carries over to modern fitting.
Feet are important for fit, as instability and small movement there can be reflected in larger movement further up the chain. This tool also measures instep height.
I brought in gravel and road bikes to get Carver’s take on ideal position differences between the two. In sort, the idea is to keep saddle-to-BB the same, and sit just a bit more upright with slightly less reach.
The Retül camera is a key part of the 3D capture system.
Carver makes sure bikes are perfectly level before starting the fit, which includes a center of mass analysis.
Carver scans the key parts of the bike with a Zin wand to record its dimensions.
Like so much in cycling, fit is a dynamic thing. What work for me 25 years ago might not be the best for me now. Retül also launched a Retül at Home app with guided routines to work on flexibility.