Small Change, Big Difference
Shimming rear wings (0°–3° adjustments) transforms foil feel in just 30 minutes. It's the cheapest upgrade you can make.
+1° (Positive Shim): Boosts lift for 7–12 knot pumps (20% easier takeoff, per NSP's Airwave kit), but adds drag for slower top ends.
-0.5° (Negative Shim): Sharpens speed (2–3 knots gain) for 20+ knots, reducing front-foot pressure by 15%.
Physics of Incidence
Angle of Attack (AoA): The stabilizer creates a downward force to balance the rider's weight and the front wing's lift. Increasing the angle (positive shim) increases this downward force, pitching the nose up (more lift). Decreasing it (negative shim) reduces drag but requires more rider input to maintain pitch.
Tests show a 10–15% turning radius tweak without re-rigging just by changing shims.
Tuning for Weight & Conditions
Axis's 2025 shim packs (stackable to ±1°) suit heavies (>85 kg) with +0.5° for stability in chop, while lights (<70 kg) favor -0.25° for glide.
Warning: Over-shim (+2°+) risks breaching (foiling out); under (-1°-) stalls pumps. Pair with 370–420 cm² stabs for balanced pitch.
Shim Guide
Sources & Further Reading
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