Importance

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Abstract

An essentially seamless bicycle frame of fiber reinforced, resin impregnated composite material and a method by which it is produced to have a top tube portion, hollow down tube portion, a seat tube portion, a head tube corner at which the top tube portion meets the down tube portion and a head tube insert is incorporated, a bottom bracket corner at which the down tube portion meets the seat tube portion and a bottom bracket insert is incorporated, and a seat tube corner at which the top tube portion meets the seat tube portion and a seat tube insert is incorporated by molding and curing of tubular preforms that were produced by rolling or wrapping layers of resin impregnated fiber material on a mandrel, each preform having been removed from the mandrel on which it was formed in an uncured tubular form. Additionally, connector tube section preforms, which are integrated into the corners, are also formed in this manner. For purposes of forming the corners, at least two integral flap portions are produced, on at least one end of at least one of the preforms to be joined, by axially slitting it. The flaps form overlapping portions that are integrally united with each other by a molding and curing operation. As a result, the frame produced requires no connecting strips or patches to join circumferentially continuous tubular components of the frame. Furthermore, the insert-incorporating corners at which the tube portions meet are also essentially seamless. A structural foam and optional non-structural, cosmetic prepreg coverings may also be incorporated into the corners. These concepts are also extended to formation of wishbone-shaped seat and chain stays that are joined to form a rear wheel assembly by an end frame with replaceable drop-outs.

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First Claim