FCS II CI Upright Medium Tri/Quad Surfboard Fins

The FCS II CI Upright Tri/Quad Fin Set – Medium offers next-level performance in a versatile setup designed in collaboration with Channel Islands Surfboards. Featuring an upright, pivot-ready template, this set delivers explosive drive, tight arc turns, and lightning-fast transitions—ideal for punchy, hollow waves or when you need instant speed off the takeoff.

This medium-sized fin set includes three main fins (tri) and two quad rears, giving you the freedom to switch between a snappy thruster setup and a looser, high-speed quad configuration depending on conditions and your riding style. With flat foils across the entire set, the CI Upright is all about control and responsiveness—making it a go-to for performance shortboards, step-downs, and hybrids with relaxed rockers.

Built for surfers in the 145–175 lb (65–80 kg) range, this set delivers an ideal balance of power, control, and agility across a range of wave conditions.

Key Features:

• Template: Upright design for tight turning radius and vertical release
• Fin Setup: FCS II Tri/Quad (5-fin) – switch between thruster and quad
• Performance: Fast start-up speed, quick direction changes, and pocket surfing precision
• Construction: Performance Core – lightweight and durable with flex for control
• Designed For: CI shortboards, hybrids, and step-downs

Medium Size Fin Specs:

• MED Side Fins: Base – 4.39″ / 111.4 mm | Depth – 4.59″ / 116.4 mm | Area – 15.04 in² / 9700 mm² | Sweep – 30.3° | Foil – Flat
• MED Center Fin: Base – 4.39″ / 111.4 mm | Depth – 4.59″ / 116.4 mm | Area – 15.04 in² / 9700 mm² | Sweep – 30.3° | Foil – Flat
• MED Quad Rears: Base – 4.04″ / 105.1 mm | Depth – 4.17″ / 108.4 mm | Area – 11.70 in² / 7929 mm² | Sweep – 33.3° | Foil – Flat

Fin Family – Reactor:

Speed. Snaps. Tight Turns. The CI Upright is part of the Reactor family, ideal for surfers who stay in the pocket, favor quick release off the top, and want precise rail-to-rail control in steep and fast waves.

The FCS II CI Upright Tri/Quad Fin Set – Medium gives you options. Go thruster for tight control and snaps or switch to quad for down-the-line speed and loosened-up feel. However you set it up, this fin delivers on power, flow, and performance.

Why Shop at Rider Shack?

We’re a small, family-run surf shop focused on premium gear for real-world surfers. Every fin set we carry is hand-selected for performance, durability, and ride feel—because we only stock what we trust. When you shop Rider Shack, you’re backed by surf expertise, personalized service, and gear that elevates every session.

Ride with confidence and dial in your style with the FCS II CI Upright Tri/Quad Fin Set – Medium—performance-driven and surf-tested for next-level control.