Before you go there, no one left Stone Sour. This change is only for the tour. Rachel Bolan is the one who plays the bass on the new double album, but he's also in Sebastian Bach's band - who's already on tour. Rachel can't be in two places at once, so the guitarist for Stone Sour announced on their Facebook page:

“I am pleased to announce that Johny Chow will be playing bass guitar with Stone Sour on the House of Gold and Bones Parts 1 & 2 tour cycle,” Rand stated. “Johny is a fantastic player and a long-time friend of the band. We are all excited to have him be part of what will be our most exciting and ambitious album cycle yet.”