Part 3: A New Perspective – How Dupli-Fit Redefines Rider Position
In Part 2, we identified the three primary contact points that determine a rider’s fit: the saddle, handlebars, and pedals—and explained how their relative positions are traditionally defined and measured. In this section, Part 3, we’ll explore how Dupli-Fit rethinks this conventional system to deliver faster, more consistent, and more intuitive results.
Dupli-Fit: Same Points, Smarter Positioning
Dupli-Fit retains the same three core contact points but introduces two significant innovations in how their relative locations are referenced and measured:
1. Reference Point (Measurement Origin)
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Traditional X-Y Fit Systems: Use the Bottom Bracket (BB) center line as the origin.
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Dupli-Fit: Uses the saddle surface at 80 mm width as the origin.
The Bottom Bracket is commonly used in traditional systems because it aligns with how bike frames are sized. However, it’s important to note that the BB is not a rider contact point. Dupli-Fit shifts the reference to the saddle, which is a direct rider interface and a consistent baseline once the frame is built up and ridden.
2. Measurement System (Coordinate Format)
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Traditional X-Y: Uses rectangular (Cartesian) coordinates — think graph paper, with locations defined by horizontal (X) and vertical (Y) distances from the origin.
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Dupli-Fit: Uses circular (polar) coordinates — where each point is defined by its distance and angle from the origin.
This approach better aligns with how fitters and bike designers naturally talk about bike geometry: in angles and lengths. For example:
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A bottom bracket angle close to 90° typically indicates an aggressive time-trial position.
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A negative handlebar angle (i.e., bars above the saddle) might indicate a more relaxed, endurance-oriented rider.
Crucially, angles are scale-independent: a 5’0” rider and a 6’0” rider might have different lengths, but the same angles—streamlining comparisons and setups across sizes and rider types.
Easing the Transition: From Traditional Fit Data to Dupli-Fit
Adoption of new systems often faces friction due to legacy data. To ease this, Dupli-Fit offers a free app that:
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Converts traditional X-Y data into Dupli-Fit format
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Allows you to graph and compare up to six bike setups
This makes it easy for riders and fitters to explore and adopt Dupli-Fit without starting from scratch.
Coming Up in Part 4:
We’ll summarize the key benefits of Dupli-Fit and share supporting data that proves what matters most: it’s both faster and more accurate.