My friend's bike has a very precise tightening instruction on the saddle. It says 5.5 Nm. Nm neans Newtonmetres, the unit for turning force. I usually teach it as moments but it is called torque. He even has a mini torque wrench that tightens it to that exactly and no further, It equates to roughly a full jar of jam held at arm's length - the turning effect it would have on your arm.
