With quickly growing environmental awareness, cycling has become a popular global activity. However, the bike riding road may be so rugged that the suspension damping status should be appropriately adjusted to make riding more comfortable. Traditionally, the damping adjustment in bikes relies on a manual operation in advance, causing inconvenience during riding. To resolve this problem, this paper aims to develop an APP-controlled hydraulic damping adjustment system for bike front fork suspension control. The microprocessor works as a core controller. G-sensor (accelerometer) is used to detect the road condition. Blade with photointerrupter circuit is designed to accurately control the DC motor rotating position for determining fork damping ratio. Moreover, APP can send control signals and receive data to/from the microprocessor via Bluetooth module between each other. Additionally, the bike driving mileage, period of time, and route can be displayed on APP instantly. The experimental results confirm that the proposed system is superior in term of robustness, accuracy, and convenience.