GB1494911A - Forked members for bicycle or like rider propelled vehicle frames - Google Patents

Abstract

1494911 Making cycle forks; welding by fusion SPEEDWELL GEAR CASE CO Ltd 27 Jan 1975 [20 Feb 1974] 7675/74 Headings B3A and B3R [Also in Division B7] A front-wheel fork for a bicycle or like riderpropelled vehicle is made of titanium and each fork limb comprises an outer tubular member, e.g. 29a, which tapers from its upper to its lower end and is reinforced internally by an inner tubular member, e.g. 29b, conforming closely in external cross-section to the internal crosssection of the outer tubular member and dimensioned to be a tight fit within the outer member. Each outer tubular member may, as shown, be reinforced in its upper part only. In the Fig. 2 embodiment each outer member 29a is formed from two halves 26 having abutting flanges 27 which are joined by TIG welding under an argon atmosphere whereby the flanges 27 melt to form internal reinforcing beads 28. The halves 26 are formed by pressing metal strips between a channel-section ferrule die and a male die of ribbed form which conform in longitudinal shape to that of the fork limbs. The inner members 29b may be made in the same manner as the outer members 29a. The lower end of each outer member 29a has a spigot 32 of a wheel mounting bracket 31 secured therein by TIG welding. The fork crown comprises a bridge piece 34 welded to each fork limb and received in a slot 39 in the fork stem 38 to which it is also welded, a top capping element 35 welded to the upper edges of the members 29a, 29b and to the stem 38 around an aperture 44 through which the stem passes, and front and rear capping elements 36, 37 welded to each fork limb and to the top capping element 43. Fig. 4 illustrates an alternative construction which differs in that the outer and inner tubular members 129a, 129b are formed from swaged tubing and in the form of the top capping element 135 and the wheel mounting brackets 133 (see also Fig. 6, not shown).