Rare earth metals, such as metallic neodymium and metallic didymium (metallic praseodymium-neodymium), are used for rare earth magnets, mainly neodymium-iron-boron magnet.

土金属，如金属钕和金属皮（金属镨，钕） ，土磁，主要钕硼磁。

Evolving process of hub dynamo which used in bicycle is presented. The performance of magnetite viz. ferrimagnetism or NdFeB is analyzed. The prospect of marketing is viewed.

摘要介绍了自行车上花鼓式发电机演变过程，分析了所磁石，即氧体或钕硼性能优劣，并进行了市场前景展望。