A Vitus Sommet uses a ZS44 zero-stack upper headset (zero stack, 44 mm). The dimensions, how to confirm it on your frame, and how it compares to the neighbouring standards.
Updated 05 September 2026.
What headset does a Vitus Sommet use?
The headset fitment standard on a Vitus Sommet, and how to pick the right part.
| Frame | Vitus Sommet |
|---|---|
| Headset standard | ZS44 (zero stack, 44 mm) |
| Cup / bearing outside diameter | 44.0 mm cup outside diameter, 43.9 to 43.95 mm head-tube bore |
| Steerer diameter | 28.6 mm (1 1/8 in) |
The Vitus Sommet uses a ZS44 zero-stack upper headset (zero stack, 44 mm), a 34.9 mm class seatpost, a 15x110 mm Boost front thru-axle at the front (15 mm x 110 mm Boost, front) and a braze-on front derailleur.
Most builds are 1x, so the front-derailleur mount note applies only to 2x setups. The rear is typically Boost 12x148; confirm your generation. The bottom bracket is covered on its own page.
SOURCES: White Industries, ZS44/EC44 headset · Park Tool, Standardized Headset Identification System (SHIS) · BikeRadar, Mountain bike axle standards: the complete guide
Questions and answers
What headset does a Vitus Sommet use?
A Vitus Sommet uses a ZS44 zero-stack upper headset (zero stack, 44 mm).