Once your calculated spring is installed, you must measure your physical sag to verify the calculation.
These assume:
: The total vertical travel of your bike's rear wheel (in mm). dhx2 spring calculator
Or in metric (kg/mm – less common for Fox): [ \textRate (kg/mm) = \frac\textRider weight (kg) \times \textLR^2\textShock stroke (mm) \times \textSag ]
✅ Measure your shock stroke (e.g., 65mm) ✅ Get bike’s leverage ratio at sag (not average) ✅ Use a real coil spring calculator (TF Tuned recommended) ✅ Start with rule‑of‑thumb rate, adjust after ride test ✅ Don’t ignore DHX2’s bottom‑out adjuster Once your calculated spring is installed, you must
Never exceed (usually 2–3 turns past zero coil play). DHX2 is sensitive to coil bind.
The physical distance the shock shaft can travel (e.g., 57mm, 63mm, 65mm, 75mm). This is usually printed on the shock body. DHX2 is sensitive to coil bind
Wear your riding gear, stand up in the "attack position" on your bike, and have an assistant measure the distance between the shock mounting eyes.
Spring Rate=Rider Weight (lbs)×Rear Wheel Travel (ins)×0.65Shock Stroke (ins)2×Desired Sag (decimal)Spring Rate equals the fraction with numerator Rider Weight (lbs) cross Rear Wheel Travel (ins) cross 0.65 and denominator Shock Stroke (ins) squared cross Desired Sag (decimal) end-fraction Example Calculation: Rear Wheel Travel: Shock Stroke: Desired Sag: