Overview
ISO 9130:2005 - "Motorcycles - Measurement method for location of centre of gravity" defines a standardized procedure to determine the centre of gravity (CG) of two‑wheeled motorcycles and of the motorcycle–rider combination. Developed by ISO/TC 22 (Road vehicles, Subcommittee SC 22), the second edition (2005) updates measurement conditions, apparatus requirements, and step‑by‑step procedures for locating the CG in the motorcycle axis system (x, y, z). The standard clarifies that its CG measurements are one input to stability analysis but do not by themselves constitute a complete evaluation of vehicle stability.
Key Topics and Requirements
- Scope: Applicable to two‑wheeled motorcycles; alternative methods permitted if equivalence is demonstrated.
- Coordinate systems: Defines a motorcycle‑fixed right‑hand axis (x longitudinal, y lateral, z vertical) and an earth‑fixed axis.
- Measurement conditions:
- Specified fill levels for fuel, oil and coolant, tyre pressure, tools in storage positions, and suspension fixed at static position.
- Rider tests use a standardized test dummy (49 CFR Part 572 subpart B) of 73.4 kg or equivalent human positioning instructions (seat, hands on handlebars, feet on footrests, defined posture and seating position).
- Apparatus & instruments: Precision square level, steel tape, angle gauge, weighing scales (accuracy to 0.1 kg), supports, rigid light platform, knife‑edge supports, and calibration weights.
- Measuring procedures:
- Detailed steps to find CG along the longitudinal (x) and lateral (y) axes using supported platform load measurements.
- Instructions on placement of motorcycle on platform, alignment tolerances (lateral inclination 0° ± 0.5°), distance measurements, and required calculations (formulated in the standard).
- Reporting: Includes a normative annex for test report content and notes that results alone cannot determine overall stability.
Applications and Who Uses It
ISO 9130:2005 is intended for professionals and organizations needing repeatable, traceable CG data:
- Motorcycle manufacturers and design engineers (vehicle dynamics, chassis tuning)
- Test laboratories and certification bodies
- Safety engineers and accident reconstruction specialists
- Research institutions studying rider–vehicle interaction and stability
- Regulatory bodies referencing standardized measurement methods
Practical uses include mass distribution analysis, longitudinal and lateral stability studies, design validation, suspension setup, and simulation model parameterization.
Related Standards
- ISO 3779 - Vehicle identification number (VIN) - Content and structure (referenced in ISO 9130)
- 49 CFR Part 572, subpart B - Anthropomorphic test device specifications (used for rider dummy reference)
Keywords: ISO 9130:2005, centre of gravity, motorcycle, measurement method, motorcycle‑rider combination, two‑wheeled motorcycles, vehicle stability, test procedure, weighing platform.