Codeofchina Inc. is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 23657-2009 Series of cycler rims. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 23657-2009:
——the definitions of symbols R1 and R2, and symbols of H and H1 are modified and merged respectively, symbols R7, Dm, L and W are added, and symbols A1, β and R3 are deleted (see Clause 4; Clause 3 of Edition 2009);
——Clause "3 Rim types, dimensions and related terms" is changed into 3 clauses: "3 Terms and definitions", "4 Symbols" and "5 Classification and designation" (see Clauses 3~5, Clause 3 of Edition 2009);
——the straight side rims with nominal width code 16 are added, the maximum value of the contour dimension parameter H1 of the straight side rim is deleted, and the parameters A1, β and R3 are deleted (see Table 1 of Edition 2009);
——the straight side rims and crotchet type rims with nominal diameter codes of 254 and 457 are added, and these original two types of rims with nominal diameter code of 251 are deleted; the values of D and D1 with nominal diameter codes of 387 and 438 are modified (see Table 2; Table 2 of Edition 2009);
——a new CT rim contour is added (see Figure 3);
——the crotchet type rims with rim contours of 27C and 29C and the maximum value of the contour dimension parameter H of crotchet type rim are added, and the tolerance of flanges of crotchet type rims are changed from ±0.5mm to (_0^(+0.5))mm (see Table 5; Table 5 of Edition 2009);
——beaded edge rims with nominal diameter code of 420 are added (see Table 7);
——in the Method 2 for measuring and gauging diameters and bead seat circumferences, the maximum value in the detail figure of the original vernier gauge for measuring the flange height G of the crotchet type rim is modified from 0.8mm to 12mm (see Figure C.8);
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——the calculation method for measured rim diameter is modified, and measurement of well width above rim tape, bead seat angle β and other rim dimensions are deleted (see C.4.2; C.4.2 of Edition 2009).
This standard is developed by adopting and revising ISO 5775-2:2015 Bicycle tyres and rims - Part 2: Rims.
Many structural adjustments have been made with respect to ISO 5775-2:2015, and a cross reference table for the clause numbers of this standard and those of ISO 5775-2:2015 is listed in Annex A.
Technical differences between this standard and ISO 5775-2:2015 are marked with perpendicular single line (|) in the outside page margin of the provisions concerned. The list for the technical differences and their reasons is shown in Annex B.
In addition, the following editorial changes have been made in this standard:
——the standard name of ISO 5775-2:2015 is modified.
This standard was proposed by China Petroleum and Chemical Industry Federation.
This standard is under the jurisdiction of SAC/TC 19 National Technical Committee on Tyres and Rims of Standardization Administration of China.
This standard was firstly issued in April 2009 and is revised for the first time.
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Introduction
This standard is different from ISO 5775-2:2015 in content arrangement. The ISO standard arranges the specification series of bicycle rims together with the general requirements of these products, and this standard redrafts the technical content on the specification series in the ISO standard. By bead structure, cycle tyres are classified into four types in China: straight side series, crotchet type series, hooked bead type series and beaded edge series, and their corresponding rims are classified into straight side rims (SS), crotchet type rims (CT), hooked bead type rims (HB) and beaded edge rims (BE), all of which have been listed in detail in this standard. Among them, beaded edge rims (BE type) are of the rim type not included in the ISO standard.
Series of cycle rims
1 Scope
This standard specifies the dimensions and tolerances of the contours of all types of cycle rims, and it gives those main rim contour dimensions necessary for tyre mounting and to fit the tyre on the rim.
This standard is applicable to the rims of various series of cycle tyres specified in GB/T 7377.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendment) applies.
GB/T 2933 Wheels and rims for pneumatic tyres - Vocabulary, designation and marking (GB/T 2933-2009, ISO 3911:2004, IDT)
GB/T 6326 Tyre terms and definitions (GB/T 6326-2014, ISO 4223-1:2002, NEQ)
GB/T 7377 Series of cycle tyres (GB/T 7377-2017, ISO 5775-1:2014, MOD)
3 Terms and definitions
For the purpose of this document, the terms and definitions given in GB/T 2933 and GB/T 6326 apply.
4 Symbols
For the purposes of this document, the following symbols apply.
A Rim width
D Specified rim diameter
D1 Measured rim diameter
D2 External diameter
Dm Measuring mandrel diameter
G Flange height
H, H1 Unobstructed minimum depth above rim base with rim tape fitted to permit tyre fitment
L Theoretical tape length
L1 Well width above rim tape
P Bead seat width
R1, R2 Flange radius
R4
Well top radius
R7 Well side radius
W Measuring tape width
5 Classification and designation
According to the types and structures, the rims are classified as follows:
——straight side (SS) rims;
——hooked bead type (HB) rims;
——crotchet type (CT) rims;
——beaded edge (BE) rims.
The application scopes, legends and main dimensions of the above four types of rims shall be in accordance with those specified in Clauses 6~9. See Clause 10 for the main dimensional requirements for rim valve holes. See Annex C for the inspection method for rim dimensions.
6 Straight side (SS) rims
6.1 SS type rims are to be used only with non-foldable tyres (rigid bead tyres). The measured rim width and the allowable rim width shall comply with the provisions of GB/T 7377.
6.2 The contour of SS rims is shown in Figure 1, and the dimensions and tolerances are given in Tables 1 and 2.
Foreword II
Introduction IV
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Classification and designation
6 Straight side (SS) rims
7 Hooked bead type (HB) rims
8 Crotchet type (CT) rims
9 Beaded edge (BE) rims
10 Rim valve holes and rim taps
Annex A (Informative) Structural changes of this standard with reference to ISO 5775-2:
Annex B (Informative) Technical differences between this standard and ISO 5775-2:2015 and their causes
Annex C (Informative) Methods for measuring and gauging bicycle rim dimensions
