Bicycle Frame

Abstract

This article is a bicycle frame that is the skeleton of a bicycle, and is composed of a main tube, a seat tube, a pair of seat stays, and a pair of chain stays. The main tube is composed of a down tube and a substantially horizontal straight portion that extends from the lower part of the down tube and connects to the lower part of the seat tube. The seat tube, the seat stays, and the chain stays are arranged in a substantially triangular shape in a front view, and the seat stays and the chain stays have a straight shape in a front view. The upper part of the seat tube smoothly and steplessly tapers in diameter toward the top, and the seat stays are connected to the middle of this tapered part. The substantially horizontal straight portion of the main tube is substantially parallel to the chain stays and is arranged below the chain stays, realizing a bicycle frame that is easy for a user to straddle. In a front view, the contour line of the upper surface of the joint between the main tube and the seat tube is composed of a curved line. At the lower part of the seat tube, at the connection between the seat tube and the chain stays, a bottom bracket shell is provided so as to penetrate the seat tube in a front view.

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