Originally Posted by
agenkin
Just an idea - how about modifying a front derailer by removing (or breaking) the tension spring and tightening up the pivot points somehow so that it does not flop around and stays put in one position. This way you could manually move the derailer inwards or outwards before starting the ride to switch the front gears. The FD is light enough by itself and your hands will stay clean because the derailer will do pushing the chain up or down the chain rings.
How about mounting a front derailleur and just a cable with an inline barrel adjuster. If the adjuster has enough travel he should be able to move the derailleur at home to the big or small ring.
People have done that with Shimano rear derailleurs to have a two speed setup. I don't know of any front derailleur with a built in barrel adjusters, though.