There's a lot going on in that cartoon.
The front rider is flatulating as the rear tire is flatting?
Or is the rear tire digging into the dirt because of the body position and "health" of the stoker thus causing the captain to exert himself?
Whatever, the placement of feet seems about right for both riders.
Is the translation "Are you even pedaling?!"
__________________
WTB: Slingshot bicycle promotional documents (catalog, pamphlets, etc).
WTB: American Cycling May - Aug, Oct, Dec 1966.
WTB: Bicycle Guide issues 1984 (any); Jun 1987; Jul, Nov/Dec 1992; Apr 1994; 1996 -1998 (any)
WTB: Bike World issue Jun 1974.