Hydraulic brake device for a bicycle

A hydraulic brake device for a bicycle which is assembled to the bicycle and is connected to a brake lever via a brake cable comprising:

• a holder, a chamber member and two side oil tubes;
• the holder assembled with the bicycle;
• and
• the chamber member assembled to the holder and having two oil tanks defined therein, each oil tank having an operating bar movably received therein, the brake cable connected with the operating bar so as to drive the operating bar, each oil tank having a brake oil drain and a side oil hole, a distance being defined between each brake oil drain and each corresponding side oil hole, each brake oil drain and each side oil hole communicating with a lateral side of the chamber member, each brake oil drain assembled to a brake hose and communicating with a brake system of the bicycle, the chamber member having two assembling grooves defined at a periphery thereof;
• two ends of each side oil tube assembled to each corresponding side oil hole and each corresponding assembling groove respectively.