I dunno nothing about bike tech so I pose this question here...
My mountain bike has a Squeaking screeching noise whenever I engaged back gear
3, 2 and 1. Other 4, 5 and 6 gear are all ok. I tried to figure out what caused this noise and not sure where the noise from. My best guess according to my online finding is RD (rear derailed) causing the noise. The chain and RD is not fully engaged whenever the back gear is on from 3 to 1. Am I right or not?