Originally Posted by
travkat
This doesn't address the fact that you may indeed not lose the 1/2mph but you might be working harder (wattage) in order to maintain that speed.
FWIW, a 0.5 MPH change in average speed is a pretty significant difference to me, on any ride with hills. Going from say, 16.5 to 17.0 on average means I was either flying up the hills or was 'hammering' (by my lowly standards) the flats the whole time.