A front derailleur including an annular chain guide for engagement and disengagement
of a bicycle chain with multiple chain rings of a crankset. The annular chain guide
may be positioned by linear guide rods. The annular chain guide may have an inner
lifting surface and an outer pulling surface for engaging diametrically opposed
corners of a chain when viewed in cross-section. The annular chain guide may have
an opening defined by a polygon having at least five sides. The motion of the annular
chain guide during a up-shift, i.e., displacement of the chain from a smaller chain
ring to a next larger chain ring includes an upward, outward and rearward linear
motion relative to a bicycle frame including upward force exerted by the annular
chain guide against the chain. The motion of the annular chain guide during a down-shift
is exactly opposite whereby the annular chain guide exerts a pulling down force
against the chain.