Joined: Jan 2008
Posts: 23,642
Likes: 1,106
From: Mans of NC & SW UT Desert
Bikes: 86 Katakura Silk, 87 Prologue X2, 88 Cimarron LE, 1975 Sekai 4000 Professional, 73 Paramount, plus more
5mm guidance above is an opinion. You will find others using less clearance. Some guide that 2mm is enough. At some point, you can get a little flex and the chainring will rub against the chain stay. At that point, you need more clearance.