There was some rumor circulating that the rear cyclor had twist handle grips to control the flight height of the boat...I'm not sure about that. After reading several of the rule clarifications, I suspect he has a gear ratio control for the group of cyclors there. One of the requests specifically asked about an automatic gear change system based on hydraulic pressure and the measurement committee said that any gear change had to be manual. While they can probably do some simple tasks, their heads are mostly down and they're really cranking out the energy - I don't think they can really do much else.
One of the cyclors confirmed that he controls the foils from his handlebars.
In some of the racing footage you can also see that they do not all output the same amount of power, the guy doing the foils doesn't go into the red like the other guys do.