>>112994
for the tour de suisse it's simply 10-15 minutes before tete de la course arrives. for the Giro stage in Switzerland, they just had the final rampa closed, but you could ride up your bike until 30 minutes before the riders arrived if you wanted, they are much more relaxed than the tour.
it's just the tour de france that does close the roads super early and restricts access. but I can't tell you what they do in Czech lands.