Let's put 34kmph vs. 41 kmph in perspective here. 7 kmph doesn't sound like much but if you run some power estimates (admittedly on flats so not too precise and also assuming solo efforts) it comes to 325 watts vs. 200 watts. Sure high tech gear will make you more efficient, but not THAT much more efficient. Supposing that both the power calculator i'm using is off and that the effect of hills on these calculations will significantly skew the numbers (which it will) that is still plausibly thought to be too much of a difference to chalk up to technological improvements in gear and training over the last 30 years.