The FCS II CI Upright Tri/Quad Fin Set – Large is a high-performance 5-fin set engineered for speed, power, and vertical surfing in critical conditions. Developed in collaboration with Channel Islands Surfboards, this fin delivers fast, responsive performance that shines in steep waves, punchy beach breaks, and high-energy surf sessions.
Designed with a more upright template, this set promotes tighter, more controlled turns—ideal for surfers who want fast directional changes and the ability to stay tight in the pocket. The full base and flat foil generate immediate drive and hold, while the included quad rears allow you to loosen up your ride and increase down-the-line speed when conditions call for it.
This large-sized set is optimized for surfers in the 175–210 lb (80–95+ kg) range, offering excellent control, drive, and projection in demanding waves.
Key Features:
- Template: Upright design for tight arcs and vertical snaps
- Fin Setup: FCS II Tri/Quad (5-fin) – ride as a thruster or quad
- Performance: Quick start-up speed, tight turning radius, and powerful hold
- Construction: Performance Core – durable and lightweight with flex for precision
- Best For: Performance shortboards, hybrids, and step-downs with relaxed rocker
Large Size Fin Specs:
- LRG Side Fins: Base – 4.50" / 114.2 mm | Depth – 4.70" / 119.3 mm | Area – 15.79 in² / 10190 mm² | Sweep – 30.3° | Foil – Flat
- LRG Center Fin: Base – 4.50" / 114.2 mm | Depth – 4.70" / 119.3 mm | Area – 15.79 in² / 10190 mm² | Sweep – 30.3° | Foil – Flat
- LRG Quad Rears: Base – 4.14" / 105.1 mm | Depth – 4.27" / 108.4 mm | Area – 12.29 in² / 7929 mm² | Sweep – 33.3° | Foil – Flat
Fin Family – Reactor:
Speed. Snaps. Tight Turns. Part of FCS’s Reactor family, the CI Upright Fin Set is made for surfers who favor vertical surfing, speed bursts, and in-the-pocket performance with less resistance and more freedom to release the tail when needed.
The FCS II CI Upright Tri/Quad Fin Set – Large is a premium option for high-performance surfers who want maximum responsiveness and the ability to shift between powerful thruster lines and fast, fluid quad setups.
Why Shop at Rider Shack?
We’re a small, family-run surf shop that’s committed to helping you ride better. At Rider Shack, we stock only gear we trust and test in the water ourselves—from fins to boards and beyond. When you buy from us, you’re backed by surf knowledge, personalized support, and a passion for performance-driven gear.
Get the power, control, and versatility your surfing deserves with the FCS II CI Upright Tri/Quad Fin Set – Large—designed to keep you fast, loose, and locked into your best surfing yet.
