ISO 24266:2020

Overview

ISO 24266:2020 - Footwear - Test methods for whole shoe - Flexing durability specifies two laboratory test methods to determine the flexing durability of whole shoes. The standard defines test apparatus, sampling and conditioning, step-by-step procedures (Method A and Method B), result reporting and required observations. The two methods can produce non-comparable results, so the choice of method must be agreed by contracting parties or referenced product standards.

Key Topics and Requirements

• Scope limits: Not applicable to whole shoes with heel height > 50 mm, flexing-area sole thickness > 25 mm, or flexing angle < 45° (see ISO 17707:2005, Clause 6).
• Two methods:
  • Method A: Typical settings include a flexing angle of 30° ±1°, a rate of 140 ±10 cycles/min, and a default test length of 50 000 cycles (optional variations by agreement).
  • Method B: Typical settings include a flexing angle of 50° ±1° (adjustable 0–50°), a flexing rate around 230 ±10 cycles/min (adjustable 100–300 cycles/min), and a default of 40 000 cycles; an optional 5 mm sole puncture may be made depending on agreement or product spec.
• Apparatus: Flexing machine (clamps/lasts aligned with flexing line), flexing last (steel axis), vernier callipers (accuracy better than 0.02 mm), and a cutting tool (Method B).
• Sampling & conditioning: Use at least one pair per test. Condition specimens in a standard atmosphere per ISO 18454 for at least 4 hours before and during testing.
• Observations & results: Record number and maximum length of new cracks, unbonding at upper/sole interfaces, and detailed damage descriptions (upper, sole, foxing/side wall). Results reported per shoe and should include test method, angle, cycles and any deviations.

Applications and Users

ISO 24266:2020 is used to assess the mechanical durability of footwear under repeated flexing-relevant for:

• Footwear manufacturers (product development and quality control)
• Independent test laboratories and certification bodies
• R&D teams evaluating materials, sole constructions and bonding methods
• Procurement and compliance teams specifying durability requirements
• Product standards writers who reference whole-shoe flexing performance

Practical benefits include standardized durability comparison, early detection of weak constructions (e.g., outsole cracking, upper-sole unbonding), and objective reporting for contractual or regulatory purposes.

Related Standards

• ISO 18454 - Standard atmospheres for conditioning and testing of footwear
• ISO 17707:2005 - Footwear - Test methods for outsoles - Flex resistance
• Prepared by ISO/TC 216 (Footwear) in collaboration with CEN/TC 309

Keywords: ISO 24266:2020, footwear flexing durability, whole shoe flex test, flexing machine, Method A, Method B, flexing cycles, conditioning, durability testing.