Colnago Y1RS Expander Bolt Kit Sizing Guide: Shaft by Frame Size Bar Screws by Spacer Height

The Colnago Y1RS expander bolt kit is TiNE's largest single-kit weight reduction — 49.4 g saved (49.1 g titanium vs 98.5 g stock). But the kit is not one-size-fits-all. Two variables determine which pieces you need: frame size (which sets the shaft length) and handlebar spacer height (which sets the handlebar screw length). Here is how to pick the right configuration.

Q: Which parts change with frame size?

Only the expander shaft changes. The Y1RS expander sits inside the carbon steerer tube above the head tube, and the shaft length must match the frame size. Larger frames need longer shafts. Every other component — locking ring, main bolt, all ten frame bolts — stays the same regardless of size.

The per-step increase matters: titanium adds only 0.4 g per size step, while steel adds 0.9 g. This means the savings actually grow with frame size — each step up saves roughly 0.5 g more than the XS baseline of 18.0 g on the shaft alone.

Q: How do spacer heights affect the kit?

The four handlebar screws are selected by spacer height — from 0 (no spacers) to 5 (maximum stack). More spacers mean longer screws. The rest of the kit (expander core, seatpost clamp, FD mount, etc.) is unaffected by spacer choice.

At zero spacers (XS baseline), the four handlebar screws weigh 3.7 g in titanium vs 7.0 g in stock — a saving of 13.2 g. That is the second-largest contributor after the expander shaft (18.0 g saved).

Q: Where does each piece go on the bike?

The kit covers two distinct zones. The expander core (shaft, locking ring, main bolt) sits inside the steerer tube above the head tube — it locks the fork to the frame. The remaining ten bolts are distributed across the bike: four handlebar screws at the stem clamp, one seatpost clamp screw at the seat tube, two FD mount screws at the bottom bracket area, and three smaller screws at the derailleur and frame.

Q: 8 colors — does the color affect weight?

No. The anodized finish is a surface treatment only — it adds negligible mass (well under 0.1 g across the entire kit). Gold, Blue, Candy, Silver, Black, Pink, Green, and Rainbow all weigh the same. Pick the color that matches your build; the 49.4 g savings are identical.