Do riders have to move at least the amount of their base movement?
A rider cannot move less than its base movement, and a &quot;blockade&quot; isn't all that effective anyway.
Your intuition about the wording in the rules is correct (Board Game Geek account needed for access). A player has to move, at minimum, their base movement every turn (assuming they have broken away from the peloton). Additionally, the rules note that riders can pass through spaces occupied by other riders if the road is completely blocked:

A rider may pass through spaces occupied by other riders ONLY when the track before him is completely blocked (fig.6b). However, the following rules must be observed:

He must choose the longest path.
He must pay 1 additional energy point for each occupied space he moves through.


So by creating a blockade, you're only causing other riders to expend more energy, when you could be using your riders to move as far as possible (it is a race, after all). You should still place your rider strategically so that other riders need to go around and waste movement.

On Board Game Geek, user Daniel Kazaniecki has uploaded a different set of rules that fix some annoying aspects of the game. He posts: &quot;After lots of brainstorming and then testing, we finally arrived to this set of rules, which seems to play out nicely for all kinds of routes, while not being too complex.&quot; After finding this, we tried out these rules and the game seemed to run more smoothly.
One of the changes they made was allowing riders to move a minimum of one space, regardless of rider type and terrain. However, they also add a rule that allows riders to pay energy to pass through any other riders, so it still washes out your idea for creating a blockade.