The big fly and the small fly of Merida bicycle make abnormal noises when riding on the central axis.

There is a sound after flying-the solution is to adjust the screw you dialed back, find the H or L screw or tighten the transmission system directly, and switch cars while tightening.

There is a sound in the middle axis-considering that it is a new car, there will be a sound when you step hard. Most of the pedals are loose. Tighten the two pedals with a wrench.

Comprehensive method: General problems will be solved by fine-tuning the front dial and the rear dial.