ISO 5775-2-2021 PDF

Full title and description

ISO 5775-2:2021 — Bicycle tyres and rims — Part 2: Rims. This international standard specifies the geometric dimensions, rim profiles, designation/marking rules and essential fitment requirements for bicycle rims (straight‑side, hooked‑bead and crotchet types), including provisions relevant to tyre mounting, valve hole placement and rim base protection.

Abstract

Part 2 of ISO 5775 defines rim contours, nominal and measured rim diameters (bead seat related), dimensional tolerances, rim types (SS, TSS, HB, C, TC), marking and designation formats, and practical requirements to ensure safe tyre fitting and compatibility with ISO 5775‑1 tyre designations. The 2021 revision updates profiles and adds clarity for tubeless‑ready and tubeless‑specific rim features and measurement methods used during verification.

General information

• Status: Published (International Standard; under systematic review).
• Publication date: March 2021.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 43.150 (Cycles).
• Edition / version: 4th edition (2021).
• Number of pages: 17.

Scope

Specifies the rim geometries and tolerances necessary for correct tyre mounting and safe use. Covers straight‑side (SS and tubeless TSS), hooked bead (HB) and crotchet (C and tubeless TC) rim types; specifies dimensional limits and measurement methods for bead seat diameter and other critical dimensions; addresses valve hole placement, rim base protection for rims with through‑drilled spoke holes, and requirements for tubeless applications (including sealing considerations). It is intended to be used together with ISO 5775‑1, which defines tyre designations and dimensions.

Key topics and requirements

• Rim types and profiles: definitions and profile drawings for SS, TSS, HB, C and TC rims and associated dimensional tolerances.
• Measured diameters and bead seat specifications: nominal codes and measurement methods to ensure tyre/rim compatibility.
• Designation and marking rules: standard formats for rim size and type marking to match tyre designations (ISO 5775 system).
• Valve hole placement and edge treatment: positioning and chamfer/rounding requirements to permit inner‑tube use and avoid tyre damage.
• Rim base protection and sealing: requirements for covering spoke holes and providing airtight sealing for tubeless applications where applicable.
• Measurement and inspection methods: prescribed procedures and references for gauging rim dimensions and verifying compliance.

Typical use and users

Used by rim and wheel manufacturers, tyre producers, product designers, test laboratories, conformity assessment bodies, procurement/specification teams and advanced bicycle workshops. It supports component design, production quality control, type designation alignment with ISO 5775‑1, and regulatory/contractual specifications for wheel assemblies.

Related standards

ISO 5775‑1 (Tyre designations and dimensions — latest edition published 2023) is the companion document specifying tyre designations that pair with ISO 5775‑2 rim dimensions. Other related references include historical ETRTO sizing conventions and national standards such as JIS D 9421 (Rims) that align with or reference ISO 5775 series provisions.

Keywords

bicycle rim, rim profile, bead seat diameter, BSD, rim marking, tubeless rim, straight‑side rim, hooked bead, crotchet rim, ISO 5775, tyre–rim compatibility, valve hole, rim base protection

FAQ

Q: What is this standard?

A: ISO 5775‑2:2021 is the fourth edition of the International Standard that defines rim geometries, dimensions, profiles and marking rules for bicycle rims to ensure compatibility with ISO tyre designations.

Q: What does it cover?

A: It covers straight‑side, hooked‑bead and crotchet rim types (including tubeless variants), dimensional tolerances and measurement methods, valve hole and rim base protection requirements, and rules for rim designation and marking to ensure safe tyre mounting and use.

Q: Who typically uses it?

A: Rim and wheel manufacturers, tyre makers, design engineers, testing labs, standards committees, procurement/specification writers and advanced service/repair professionals who need to ensure tyre–rim compatibility and safe wheel design.

Q: Is it current or superseded?

A: ISO 5775‑2:2021 is the current published edition (4th edition, March 2021). Earlier editions such as ISO 5775‑2:2015 have been withdrawn and replaced by the 2021 edition.

Q: Is it part of a series?

A: Yes — it is Part 2 of the ISO 5775 series. Part 1 covers tyre designations and dimensions (most recent Part 1 edition published in 2023) and together the parts provide a complete tyre–rim sizing and marking system.

Q: What are the key keywords?

A: Rim profile, bead seat diameter (BSD), straight‑side (SS), hooked bead (HB), crotchet (C), tubeless (TSS/TC), rim marking, tyre–rim compatibility.