Originally Posted by biker7
Hi 53...yup that's right,
...for posterity here is the simple trig:
sin (change in angle) X 76cm = change in setback
sin (1.5 deg) X 76 = 1.99 which is ~2.0 cm
sin (1.0 deg) X 76 = 1.33 cm
for what its worth the net setback difference for small angles are proportional to the angle change, i.e. 1 deg/1.5 deg = 1.33cm/2.0 cm
HTH,
George
i hate to be a math nazi, but your trig is wrong.
you've kind of, but not really, calculated the change in height of his saddle given a change in seat tube angle. even if you were trying to do that you did it wrong.
the proper formula is
76*(cos(72)-cos(73.5)) = 1.9cm forward
76*(cos(72)-cos(72.5)) = 0.63cm
if you were trying to caluclate the change in height:
76*(sin(73.5)-sin(72)) = 0.59 cm higher