DONT EVER BUY THIS PIECE OF SHIT
IT'S COMPLETE AND UTTER TRASH
YOU WILL REGRET IT
HOLY SHIT I LOOKED FOR THE PROBLEM EVERYWHERE BUT IT TURNS OUT IT REALLY IS THE WEAK SPRING ON THIS SHIMANO M4120 PIECE OF S-H-I-T
I AM SO ANGRY AAAAAAAA
THE PIVOT SPRING IS SO WEAK IT FUCKED UP MY FRAME
GOD FUCKING DAMN
DECEPTIVE LOOKING PIECE OF S-H-I-T-M-A-N-O
I FUCKING HATE YOU AND HOPE YOU DIEE
RRRREEEEEEEEE
GOD FUCKING DAAAAAAAMN

TL;DR: don't buy shimano m4120, pivot spring is so weak it will cause chain suck and the top chain run goes fucking limp from there mere rotating inertia of a 11-42 cassette.
God fucking damn, two nukes wasn't enough.