1. Sound caused by friction of bearings or moving rotor parts.
2. The sound caused by overload.
3. There is abnormal noise at the joint between the seat tube and the frame.
4. It is not normal to step on the pedal.
5. When stepping on the pedal, the pedal makes an abnormal sound.
6. The rim has abnormal noise.
7. The disc brake makes abnormal noise when braking.
There are some possible solutions to the above problems:
1. Try using some oil to lubricate the noise caused by bearing friction or movable runner parts friction.
2. For the sound caused by heavy load, you can try to reduce the load.
3. For the abnormal sound at the joint between saddle tube and frame, try to pull out the saddle tube and clean the inner wall at the joint between saddle tube and frame and the joint between frame and saddle tube.
4. For abnormal pedal sound when pedaling, you can try to replace the pedal or remove the pedal for maintenance.
5. For the abnormal sound at the pedal tooth plate when pedaling, if it is a square-hole tooth plate, it can be tightened with an Allen screw. If it is an integral denture, this will not happen in most cases. If it is indeed an integral dental tray, you can try to replace the sealing ring between the left thigh and the dental tray and tighten the screws.
6. For abnormal noise at the rim, you can check whether the spokes are loose when the speed reaches 30 kilometers per hour. If it is, it can be adjusted by ring regulator.
7. For the abnormal sound of the disc brake when braking, if the brake makes an unpleasant sound without fault, it may be that the incoming piece was smashed into small pieces by a small stone. You can try to clean up the piece and small stone that came in.
The above are some possible treatment methods, but the specific treatment methods should be judged and selected according to specific reasons. If you can't solve it by yourself, please contact a professional for maintenance in time.