Colnago Y1RS Titanium Expander Bolt Kit 49g Core Assembly 58%

The Colnago Y1RS is a frame built around integration. Fully internal routing, a clean cockpit, and a compression plug system that holds it all together. That compression plug — the expander assembly — sits at the very core of the frame, and it is made entirely of steel.

The TiNE titanium expander bolt kit for the Y1RS replaces that entire assembly with Grade 5 Ti-6Al-4V, bringing the total from 98.5g down to 49.1g — a reduction of 49.4g, or roughly 50% of the original weight. It is the largest single-kit weight reduction in the TiNE catalog.

Why the Expander Assembly Dominates the Weight Savings

The expander assembly is not a single bolt — it is a three-part system: the expansion shaft, the locking ring, and the main bolt. Together, these three pieces account for the majority of the weight in the stock setup.

The expansion shaft alone saves 18.0g — more than many complete bolt kits for other products. The shaft is a long, solid steel rod that runs through the head tube, and replacing it with titanium removes weight from the very center of the frame.

The Remaining 7 Positions: 20.7g Across 10 Bolts

Beyond the expander core, the kit replaces 10 additional bolts across 7 frame positions: limit screw, top pin screw, decorative cover screw, two front derailleur bolts, seatpost clamp bolt, and four handlebar bolts. These add 21.9g (TiNE) versus 42.6g (stock), saving 20.7g.

Combined with the core savings of 28.7g, the full kit delivers 49.4g of weight reduction — and the core accounts for 58% of the total.

Frame Size Matters: Larger Frames Save More

The expansion shaft length varies by frame size. Every step up in size adds roughly 0.9g to the stock shaft and 0.4g to the TiNE shaft — meaning the weight gap grows by about 0.5g per size increment. Riders with larger frames benefit slightly more from the titanium upgrade.

Handlebar bolt selection also varies by spacer count (0 to 5 spacers), with each step adding 5mm in bolt length and roughly 0.4–0.5g per bolt. The correct bolt lengths are determined by the number of spacers under the stem.