The S-Works Rapide Post is engineered to reduce drag where airflow is highest. Using our Moving Leg Mannequin, we discovered pedaling drives high speed air directly onto the post, making it a critical aero surface. A deeper profile with reduced frontal area and our thinnest section ever in this zone delivers cleaner flow and improved aero performance, while our refined FACT carbon layup preserves balanced compliance for all day comfort. D‑Shape design and optimized lay-up construction deliver the most aerodynamic and comfortable seat post.FACT carbon construction blends durability with comfort.Lightweight, precision-engineered saddle hardware enables fast, accurate, effortless adjustments.Fits Tarmac SL9, Crux 5 & Tarmac SL8Available in four sizes: 330mm x 0 offset, 380mm x 0 offset, 330mm x 20mm offset, 380mm x 20mm offsetSystem Weight Limit: 275lbs / 125kg