8488 International Standard (ISO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAH OPrAHW3AUMA HIO CTAHAAPTW3ALMW-ORGANISATION INTERNATIONALE DE NORMALISATION Cycles - Screw threads used to assemble head fittings on bicycle forks Cycles -- Filetages utilises pour I'assemblage des raccessoires) de direction sur les fourches de bicyclettes First edition - 1986-06-15 UDC 629.118.3 : 621.882. 082 (3) 9861-8858 0S1 Ref. No. ISO 8488-1986 (E) Descriptors : road vehicles, bicycles, forks, locknuts, screw threads, dimensions, dimensional tolerances, designation. Price based on 6 pages Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through iSo technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with Iso, also take part in the work. Draft international Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 8488 was prepared by Technical Committee ISO/TC 149, Cycles, Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition,unless otherwise stated International Organization for Standardization, 1986 ? Printed in Switzerland ted without license from IHS Not for Resale ISO 8488-1986 (E) INTERNATIONAL STANDARD Screw threads used to assemble head fittings Cycles - on bicycle forks Introduction The French and UK threads are clearly not interchangeable with the BsC thread due to outside diameter and t.p.i, respectively. Inch screw threads of BSC (British Standard Cycle) thread pro- The Italian thread is also not compatible due to the Italian flank file are used extensively throughout the world for various angle of 550 compared to the BSC angle of 60°. applications on bicycle components, and have been stan- dardized in national standards. The purpose of this document is As referred to in the second paragraph above, this ISO system to provide an international Standard for the particular screw of screw threads is intended to replace the 1.000 in × 24 t.p.i. thread used to assemble the head race and locknut on bicycle BSC threading, but the continued usage of the other non- forks; it is based on the use of the Iso basic thread profile and compatible threadings is not in harmony with the objects of complies as far as is practicable with existing International Iso worldwide standardization, and wherever and as soon as Standards for general purpose screw threads. possible, it is strongly recommended that all new products change over to the new Iso threads detailed herein. The change to an IsO system of screw threads will inevitably take a long time to complete in view of the millions of bicycles It should also be noted that where the design size of the fork now in use which employ Bsc thread profile inch screw column tube is already 25,4 mm (1.000 in) nominal, the thread threads and for which replacement spare parts will be required. cutting of this new ISo thread willincrease the truncation and For this reason, in order to minimize changes in production facilitate assembly. methods during the changeover to the International Standard, and also to secure satisfactory interchangeability with the BSC Attention should be paid to Iso 6692 for the proposals on screw threads now used, the IsO screw thread in this Inter- thread identification marking. national Standard has the same pitch as that of the 1.000