Speed Wobble Risk Calculator
Assess speed wobble risk based on truck tightness, bushing type, wheelbase, speed, and rider weight.
What causes speed wobbles:
Speed wobbles (also called death wobbles or shimmy) occur when small steering oscillations amplify through positive feedback at high speed. The trucks pivot, the deck tilts, and each correction overcorrects the previous one — building into violent oscillations. Understanding the physics helps you set up your board to avoid them.
Key factors in wobble onset:
The critical speed at which wobbles begin depends on several mechanical factors:
Wobble onset speed ∝ √(Bushing stiffness × Wheelbase / Rider height × Truck angle)
Higher bushing stiffness → higher onset speed (more stable) Longer wheelbase → higher onset speed (more stable) Lower truck angle → higher onset speed (more stable) Higher center of gravity → lower onset speed (less stable)
Stability scoring by factor:
| Factor | Stable (0 pts) | Moderate (1 pt) | Unstable (2 pts) |
|---|---|---|---|
| Bushings | Hard (96A+) | Medium (90–95A) | Soft (< 90A) |
| Wheelbase | 30"+ (longboard) | 22–30" | < 22" (standard) |
| Truck angle | < 42° (Paris 43°) | 43–48° | 50°+ (standard TKP) |
| Speed | < 25 mph | 25–35 mph | 35+ mph |
| Rider weight | Light (< 68 kg) | Medium (68–90 kg) | Heavy (> 90 kg) |
Bushing durometer guide by rider weight:
| Rider Weight | Soft Carve | All-Around | Downhill |
|---|---|---|---|
| < 55 kg | 78A | 85A | 90A |
| 55–70 kg | 82A | 87A | 93A |
| 70–85 kg | 85A | 90A | 95A |
| 85–100 kg | 88A | 93A | 97A |
| > 100 kg | 90A | 95A | 98A |
Example assessment:
A rider (80 kg) bombing a hill at 30 mph:
- Bushings: 87A (medium) → 1 point
- Wheelbase: 36" (longboard) → 0 points
- Truck angle: 50° → 2 points
- Speed: 30 mph → 1 point
- Weight: 80 kg → 1 point
- Total: 5 points = Moderate risk
- Fix: Switch to 43° baseplates and 93A+ bushings
How to prevent speed wobbles:
- Tighten the rear truck slightly more than the front
- Use harder bushings (especially rear)
- Lower your center of gravity by bending your knees
- Use split-angle trucks (lower angle rear, higher angle front)
- Shift weight to the front foot — wobbles always start at the rear
Emergency recovery:
If wobbles start, do NOT grab the board or stand up straight. Instead, carve wide to bleed speed, crouch low, and shift weight aggressively to your front foot. Tightening your muscles makes wobbles worse — staying loose and weighting the front is the key to riding them out.