Originally Posted by
FBinNY
+1
As far as torque specs on bikes, it's more complex than many believe. The ratio of torque to holding power (bolt tension) varies with thread friction among other things, so it's important to know if the torque spec is for a dry or wet thread. Also because there's a difference between static and sliding friction, bolts must be torqued to spec. in a single steady motion, not tightened by degrees. Also the torque to break a bolt loose will always be higher than the torque just applied to tighten it.
Torque wrenches can be very useful where all the manufacturing specs are carefully adhered to, but otherwise they can be misleading, and create as many problems as they solve. They are often most useful at high loads but not at all a replacement for good hand feel at the low end of the range.
I suspect this is the case here. The seat post clamp is plastic, combined with a stainless steel M5 bolt, creating less frction. I do not believe there is grease on the bolt.
The owner of the LBS, where I bought this bike, had shown me how to tighten the seat clamp without a torque wrench. However, being new to carbon and not use to what 4.5Nm feels like, I felt a torque wrench would help.