Overview - ISO 5902:2013 (Alpine skis - Determination of elastic properties)
ISO 5902:2013 specifies standardized laboratory measurement methods for determining the elastic properties of alpine skis. The standard defines how to calculate resistance of defined ski regions to bending (spring constants) and torsion (torsional spring constant) so that test data from different manufacturers and laboratories are comparable. ISO 5902:2013 is intended for finished skis (no mounted parts) and does not attempt to rate ski quality.
Key topics and technical requirements
- Scope and purpose: Laboratory procedures to measure elastic properties of alpine skis to ensure comparability of published data.
- Terms and definitions: Key metrics include the centre, shovel, rear, forebody and afterbody spring constants (c, in N/mm); spring constant balance (B); and torsional spring constant (cT, in N·m/°).
- Apparatus: Detailed requirements for fixtures and instruments:
- Two adjustable low‑friction roller supports and a load applicator for centre bending.
- Clamping device (flat jaw + clamps) and load roller for shovel, rear, forebody and afterbody tests.
- Torsion head and angular scale for torsion tests.
- Measurement accuracies (e.g., load accuracy ±2 N, deflection ±0.5 mm, torsion ±0.5°).
- Sampling and conditioning: Tests on finished skis; recommended test lengths 150, 180 or 200 cm (choose nearest). Condition skis at 23 °C ± 5 °C for at least 2 h before testing.
- Test procedures:
- Centre spring constant (cM): quasi‑static load 300 N (preload 20 N), specific support spacing and clamp locations.
- Shovel and rear (cS, cR): typical test load 150 N (reduce to 100 N if deflection >50 mm), pre‑load 20 N.
- Spring constant balance (B): two bending tests with 50 N loads.
- Torsion (cT): quasi‑static torque (recommendation for very stiff skis), read torsion angle after 2–5 s.
- Results and tolerances: Mean of three tests reported. Recommended tolerances for published data: ±10% for both spring and torsional constants.
- Test report: Must reference ISO 5902 and include manufacturer, model, nominal length, registration number, test results and any deviations.
Applications and users
ISO 5902:2013 is used by:
- Ski manufacturers for design validation, product data sheets and comparative specifications.
- Testing laboratories and research institutions for reproducible measurement of ski bending and torsion behavior.
- R&D and materials engineers for prototype evaluation and structural tuning.
- Standards bodies and quality assurance teams who need consistent, repeatable elastic property measurements.
Note: the standard ensures comparable mechanical data but does not provide a direct assessment of ski performance or user quality.
Related standards
- ISO 6289 - Skis: Vocabulary (normative reference used by ISO 5902).
- Prepared by ISO/TC 83 (Sports and recreational equipment), Subcommittee SC 4 (Snowsports equipment).
