Flux cutting in a uniform magnetic field

Say we have a uniform magnetic field acting into the page, and we have a bicycle wheel which is spinning at a constant tangential velocity $v$. Each spoke has a equal length, $l$. Reading has told me that there is a constant EMF induced in the spokes, but I fail to see why - according to Faraday's law $$E = -N d\phi/dt$$ there shouldn't be a flux induced, as the flux doesn't change when the spokes cut across it? If the field is uniform, and spokes simply move across but are always perpendicular to the field, I don't understand why $d\phi$ isn't 0. For a similar reason, I don't understand why there is a force when a dc current is in a magnetic field - no emf would be induced, so why does Fleming's left hand rule say there will be a force acting?