The 7 bearings of a bicycle, including the bottom bracket, hubs, pedals, headset, and derailleur pulleys, are crucial components that require appropriate bearing quality for comfort and safety while riding; exposure to water, dirt, or excessive looseness can affect performance and generate noise, thus necessitating bearings with high precision and external  sealing.
A bicycle usually has seven places where bearings need to be installed so that the whole bike can run smoothly. Common components include the bottom bracket, wheel hub, pedal, head bowl, guide wheel, etc. The performance of a bicycle largely depends on the bearing. And different parts have their suitable bearings.
To provide users with a comfortable and safe riding experience, bearings need high precision. Some parts need external sealing protection. Because once water and dirt enter the bearing or use a loose bearing, it will cause the wheel to shake and make noise when it rotates.
