1. Limb Alignment & Pocket Geometry
On modern International Limb Fitting (ILF) and Formula-style risers, precision limb pocket alignment ensures both limbs flex through an identical vertical plane. Misaligned limbs impart lateral torque to the bowstring during expansion, creating unpredictable horizontal arrow drift:
- Mount a set of beiter limb gauges (or contrasting tape strips) near the base and tips of both upper and lower limbs.
- Rest the bow on a stable fixture or hang it from the top limb pocket. Stand 2 meters behind the bow and visually align the bowstring down the center axis of the riser cutout.
- The bowstring should slice through the center marks of both limb gauges, the stabilizer bushing hole, and the limb pocket alignment bolts.
- If the string tracks off-center, adjust the lateral limb pocket dovetail screws in 1/8-turn increments until true collinearity is achieved.
2. Tiller Calibration (Upper vs. Lower Limb Balance)
Tiller is the measurement difference between the bowstring and the base of each limb, taken perpendicular to the string at the junction where the limb enters the riser pocket:
| Shooting Discipline | Release Style | Recommended Tiller Differential | Biomechanical Rationale |
|---|---|---|---|
| Olympic Recurve | Split Finger (Mediterranean: 1 above, 2 below) | +3.0mm to +5.0mm (+1/8" to +3/16") Positive (Upper measurement larger) | The arrow sits approximately 2.5cm above the true mechanical center of the bowstring. Positive tiller ensures both limb tips return to static rest at the exact same millisecond upon release. |
| Barebow Archery | String Walking (Deep craws down the string) | 0.0mm (Neutral) to -2.0mm Negative | Moving the drawing hand downward increases downward leverage on the lower limb; neutral or slightly negative tiller prevents excessive lower limb strain. |
| Traditional / Longbow | Three-Under (No string crawl) | 0.0mm to +2.0mm Neutral/Mild Positive | Minimizes finger pinch and equalizes dynamic draw effort across both limbs. |
3. Brace Height Sweet Spot Optimization
Brace height is the static distance from the deepest point of the riser grip (pivot point) to the bowstring. Finding the acoustic "sweet spot" minimizes hand shock, stabilizes arrow launch velocity, and reduces riser vibration:
| Overall Bow Length | Riser & Limb Combination | Standard Brace Height Range | Metric Range |
|---|---|---|---|
| 66 Inches | 25" Riser + Short Limbs (or 23" + Medium) | 8.10" – 8.60" | 20.5 cm – 21.8 cm |
| 68 Inches | 25" Riser + Medium Limbs (or 27" + Short) | 8.25" – 8.85" | 21.0 cm – 22.5 cm |
| 70 Inches | 25" Riser + Long Limbs (or 27" + Medium) | 8.50" – 9.10" | 21.6 cm – 23.1 cm |
| 72 Inches | 27" Riser + Long Limbs | 8.75" – 9.35" | 22.2 cm – 23.7 cm |
Acoustic Tuning Protocol: Start at the lower end of your bow length's range. Shoot 3 arrows, add 5 twists to the bowstring (which raises brace height by ~2mm), and repeat. Note the shot noise: when the bow transitions from a loud metallic buzz to a soft, low-frequency thump with minimal residual stabilizer oscillation, you have reached the harmonic sweet spot.
4. Center Shot & Arrow Rest Geometry
Due to finger release paradox, an Olympic recurve arrow must not be set dead center in the riser window:
- Position your arrow on the rest against the cushion plunger button.
- Stand behind the bow, aligning the string down the center of the limbs and riser.
- The arrow point should protrude slightly to the left (for a right-handed archer) by approximately half the shaft diameter (1.5mm to 2.5mm).
- This offset provides the clearance margin required for the shaft column to flex inward around the bow grip upon release without ricocheting off the riser shelf.
Log Equipment Specs in GoldTracker: Store your verified brace height, upper/lower tiller, limb pocket bolt turns, and plunger tension directly inside GoldTracker's equipment garage. Track how minor setup changes impact your 72-arrow scoring averages over time.