The problem here was that they caught my dad picking me up from the airport with my car (on the R300 towards Cape Town International) on stretch of road not clearly marked (it is 90, the caught him for going 90 in 60km/h zone). So I suspect the road works meant to have it as a 60km/h zone, but no sign said that. And the whole "how will they catch bikes" also made me "???" when I first heard this (and no, not from my gran...)
I'm thinking of appealing this though, how much "warning" do they need to give you in either direction when it comes to speed signs/cameras? I know at least that they have to do THAT. Because if the sign was down (according to my dad, he didn't see/it wasn't clearly marked that the speed changed) Then I'm going to just write an appeal letter.