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Top-Swing ®
Most front derailers use a parallelogram which is fixed (attached to the derailer body) at the top, with the moveable cage attached to the bottom link of the parallelogram. Many of the newer Shimano units are built "upside down": the bottom of the parallelogram is fixed in place and the cage attaches to the top link.
A peculiarity of Top-Swing ® derailers is that the limit stop adjustment screws are reversed, so that the outer screw limits inward travel, and vice versa.
Top-Swing ® derailers clamp on to the seat tube lower down than bottom-swing units. (Shimano E-type derailers don't even attach to the seat tube, but are held on by the bottom bracket mounting ring.) Some frames made for use with top-swing derailers will not permit the installation of conventional bottom-swing derailers, because there's a bottle braze on in the way. Some suspension frames also require a top-swing front derailer for clearance reasons.
Top-Swing ® or bottom-swing derailers can be (and are) made in either top-pull or bottom-pull versions. (This has to do with the direction from which the cable approaches.)
