Originally Posted by
sstorkel
You seem to be putting quite a lot of faith into some random website. Are you sure it that it's able to accurately model the real world using simple polynomial equations?
There are a number of assumptions built into that calculator. But the magnitudes are correct, and the equations are derived from actual measurement. (assumptions in Kreuzotter's calculator are things like frontal area as a function of mass and height, etc, to make the interface easier to use. analyticcyclling has a whole bunch more, and you can fiddle with all the variables you care to. )
Physics is a *****, man. It doesn't care what you paid for your bike. It's not going to be impressed that some salesman took your money. It only cares about forces, and simply put, weight doesn't matter nearly as much as people like to pretend it does.