Joined: Nov 2010
Posts: 15,315
Likes: 903
From: Tixkokob, Yucatán, México
Bikes: 79 Trek 930, 80 Trek 414, 84 Schwinn Letour Luxe (coupled), 92 Schwinn Paramount PDG 5
I set mine by the rollout method. Then adjust it against the kilometer markers on the road. It may or may not be any more accurate, but it does agree with officialdom. How accurate a measurement are you going to get using chalk and reading mm? Even using a pencil?