Abstract: A bicycle frame includes a front part and a rear part. The front part includes head tube, a seat tube and a down tube connected between the head tube and the seat tube. A first connection portion is connected to the conjunction portion of the seat tube and the down tube. The rear part includes a second connection portion, a connection plate extending from a top end of the second connection portion, and two chain stays and two seat stays extending from the connection plate. The connection plate is fixed to the seat tube by at least one bolt, and the first and second connection portions are connected to each other by at least two bolts. The first connection portion includes a ridge which is engaged with the groove defined in the second connection portion.

Abstract: A recess is defined in one of the top tube, the down tube and the seat tube of a bicycle frame and a power supply unit is engaged with the recess. The power supply unit includes an engaging frame engaged with the recess and a battery is removably engaged with a main space defined in the engaging frame. The engaging frame includes a chamber defined in an end thereof and a control box is received in the chamber so as to be electrically connected with the control box. The top surface of the battery is in flush with the one of the top tube, the down tube and the seat tube. An ON/OFF switch is installed on a top of the engaging frame and an indication bulb is installed on a top of the battery for convenience of observation by the user.

Abstract: A tube connection assembly of a bicycle frame includes a bi-forked portion formed by a hollow rectangular tube; one end of the rectangular tube being bi-forked as two halves; each half having a positioning groove; and a combining portion formed by two plates which are connected as a shape corresponding to that of the positioning groove and the bi-forked portion so that in assembly the combining portion is assembled to the bi-forked portion; and connection area of the bi-forked portion and combining portion being welded.