I am looking to switch out the brakes on my 2013 Stache 7. Looking to swap out the Avid brakes for the SLX. My only questions is I'm not sure what the spec/size is for the mounting options on my bike (i.s., 51mm, 74mm) I a noob with this stuff and have no idea what means what, just want to make sure I order the correct size for my bike. Thanks guys/gals :skep: