Overview - ISO 17707:2005 (Footwear - Outsole flex resistance)
ISO 17707:2005 specifies a laboratory test method for determining the flex resistance of footwear outsoles. The procedure measures cut growth and crack initiation caused by repeated flexing of the outsole material and surface pattern. It applies to outsoles with a maximum longitudinal rigidity of 30 N and is intended to assess how sole materials and tread patterns influence durability under flexing.
Key topics and technical requirements
- Scope: Test designed for outsoles with longitudinal rigidity ≤ 30 N (measured at 45° flex).
- Rigidity test: Outsole forepart is clamped and flexed at a bending rate of 100 ± 10 mm/min to 45°; force recorded to ±1 N. Outsoles requiring >30 N are excluded from flex resistance testing.
- Flexing device: Uses a 30 ± 0.1 mm diameter mandrel, clamped ends, and a mechanism that flexes the outsole through 90 ± 2° at a constant rate (device capability typically 135–150 cycles/min).
- Cut initiation: A chisel is pushed through the full thickness at the flexing line; initial cut length L(o) is measured.
- End measurement: After 30 000 flex cycles, final cut length L(f) is recorded; cut growth = L(f) − L(o). Additional cracks and their lengths are noted.
- Sampling & conditioning: Minimum three samples (covering size range where possible) and conditioning per EN 12222. Test-piece insole specifications: cellulose board, 2 ± 0.1 mm thickness, apparent bulk density 0.55 ± 0.05 g/cm³.
- Measurement accuracy: Cut length to 0.1 mm; longest crack to 0.5 mm.
- Reporting: Include results, sample identification, reference to ISO 17707, test date and any deviations.
Applications and who uses it
- Footwear manufacturers and outsole compound formulators use ISO 17707 to evaluate material selection, tread pattern design, and comparative durability.
- Quality assurance and R&D teams apply the method to screen outsoles for flex-induced cut growth, inform design changes, and validate supplier claims.
- Testing laboratories offering footwear durability tests will implement this standard to provide objective, repeatable results for clients.
- Regulatory bodies and procurement teams may reference outcomes when specifying performance requirements for safety and work footwear.
Related standards
- EN ISO 20344:2004 - Personal protective equipment - Test methods for footwear (basis for method)
- EN 12222 - Standard atmospheres for conditioning and testing of footwear
- EN ISO 534 - Paper and board thickness/density (for insole preparation)
Keywords: ISO 17707:2005, flex resistance, outsole test methods, footwear durability, cut growth, crack initiation, outsole rigidity.
