The pursuit of performance
In our recent history, driven by the desire to constantly elevate the performance of steel frames, we felt the need to overcome the limits of the historic BSA and Italian threaded standards.
The goal was to adopt an oversized bottom bracket shell, intervening concretely on a crucial area for the bicycle’s dynamic behavior. A larger diameter allows for an increased coupling surface with oversize tubing, drastically improving the torsional stiffness of the entire frame.
From Press Fit to T47
Our first experiments date back to 2015 with the SB/03 models, on which we tested the Press Fit standard. The transition from a diameter of approximately 40 mm to one near 50 mm offered a clear structural advantage, especially when combined with oversized tubing designed for maximum performance.
However, we must be honest: the Press Fit standard never guaranteed consistent reliability over time. If this was true for composite frames, it was even more so for metal frames, subject to micro-deformations due to the heat of welding. Just as we were looking for the perfect compromise at the end of 2015, the T47 standard appeared on the horizon, introduced by Chris King in collaboration with Argonaut Cycles. While many builders welcomed yet another standard with skepticism, for us, it represented the best of two worlds: the stiffness of an oversized diameter combined with the reliability of threading.
Innovation and in-house production
Being among the first builders to adopt T47 in Europe was not without its challenges. Implementing a new standard meant redesigning components from scratch: defining ideal tolerances, calculating thermal welding deformations, and selecting the most suitable alloys to contain weight without sacrificing strength.
Independently, we also designed and had dedicated taps manufactured for this new standard. Furthermore, many may remember our proprietary production of T47 bottom bracket cups compatible with the Campagnolo Ultra-Torque standard. For a time, we were the only ones exporting this solution worldwide, dedicated to those who wished to mount Campagnolo groupsets on T47 standard frames.
The latest version
The version of the bottom bracket shell offered today benefits from countless studies, welding tests, and technical details refined over many years of production. Each piece is made to our design in the Bergamo area using precision CNC machining, including weight-saving milling. We exclusively use certified stainless steel and titanium alloys, a selection resulting from rigorous testing.
Each shell is embellished with the engraving of the Stelbel logo and, often, the frame’s serial number. It is a discreet but fundamental detail: we believe that even a hidden component deserves the same obsessive attention as what remains visible.
T47 in the Stelbel range
With the latest evolution introduced at the end of 2025 — the lightest and most resistant to thermal deformation ever produced — we have reached a level of satisfaction such that we are extending the T47 standard to the entire Stelbel range (with the sole exception of the INOX model).
The bottom bracket shell is the convergence node for some of the most important forces acting on the frame. The care we dedicate to this detail defines the Stelbel attitude: a rigorous technical approach that accepts no compromises on quality.
