- ETRTO STANDARDS MANUAL 2015 PDF CODE
- ETRTO STANDARDS MANUAL 2015 PDF ISO
- ETRTO STANDARDS MANUAL 2015 PDF PLUS
The diameters of straight-side and crochet-type rims are measured as the bead seat diameter (BSD). The standard widths of hooked-bead rims are: The standard widths of crochet-type rims are: The standard widths of straight-side rims are: The nominal width of a rim is the inner width between the straight sides or beads as one can easily measure it with a caliper (see the standard for drawings and exact measurement procedures).
ETRTO STANDARDS MANUAL 2015 PDF CODE
The rim type codes SS or HB precede the rim designation, whereas code C is appended to the nominal width. Rims are designated by their nominal rim diameter and their nominal width, separated by a cross (×). Without a bead seat, the primary designation of the diameter in terms of the bead seat is not applicable, and the governing diameter is the OD. The tire is held in position radially by the hook without a bead seat playing a role. The distinction is primarily that hooked-bead rims lack the defined bead seat of straight side and hooked bead rims. On modern bikes crochet rims are most common and hooked bead rims are rare. It distinguishes betweenīoth crochet (C) and hooked-bead (HB) rims have inner profiles that curve inwards near the outside diameter of the rim to provide a hook that helps retain the tire bead under high pressure.
ETRTO STANDARDS MANUAL 2015 PDF ISO
ISO 5775-2 defines designations for bicycle rims. They are marked with an overall diameter code and a nominal section-width code, separated by a cross (×). Such older markings can be appended to the ISO 5775 designation in parentheses.īeaded-edge tires are mounted on hooked-bead rims. Older markings of wired-edge tires can be converted to ISO 5775 designations with the help of the following table: 584 mm tires are also marketed as 27.5" (outer diam.) tires. Note how in the below sorted table the "inches" measure is inconsistent with the mm measures, if height varies: Some 28" tires then have less mm than a 27" tire. The standard defines a set of nominal section widths for wired-edge tires and lists recommended rim widths for each: The ISO 5775-1 standard also defines procedures for measuring tires and for calculating from the marking the maximum dimensions of a tire, which are needed by designers to determine clearance distances to other bicycle components.
ETRTO STANDARDS MANUAL 2015 PDF PLUS
The overall diameter of the tire is then the rim diameter plus twice the tire's section height. The section height of a tire is usually identical to its section width (for tires less than 28 mm, 2.5 mm have to be added to the width to get the height). The inner width of the rim on which the tire is mounted should be about 65% of the tire's nominal section width for tires smaller than 30 mm and 55% for those larger. The standard notes that the minimum inflation pressure recommended is 300 kPa for narrow tires (25 mm section width or less), 200 kPa for other sizes in normal highway service, and 150 kPa for off-the-road service.
Crochet-type rims are not the same as hooked-bead rims. Wired-edge tires can be mounted on straight-side or crochet-type (aka hook bead) rims.