Route Vác -> Galgaguta -> Galgamácsa -> Vác circle  

The first 40km is more hilly, the second is more flat. Highlights of the tour:

• there is a heavy climb between Penc and Keszeg, getting steeper and steeper just before arriving to Keszeg
• the 2nd half of the road between Nézsa and Nógrádsáp is one of the most beatuiful parts, almost level very good pavement, beautiful scenery
• Legénd is one sweet village, worth spending some time here
• the road passes a beautiful renovated castle on your left in Nógrádsáp in the village center
  
• there is a short but steep climb before Galgaguta, the descent is a bit tricky, but you could easily accelerate to 60km/h with a MTB on the way down. Watch out for the badly paved railroad crossing just at the bottom!
• from here the road is basically flat, with some minor climbs
• the worst pavement is between Váckisújfalu and Váchartyán, both on the climb and the fast descent, this latter could be tricky, there is basically no best path available, be very cautious if you are riding a road bike here
• the road gets a bit busy after Csörög, but still totally acceptable
• arrive back to Vác, city center will be to your a few corners to the left, worth checking out the nicely renovated main square and the gourmet sweets at the nort end on your right! :)

If you still feel fit here, you can ride back to Budapest, otherwise just catch the train back.