Derailleurs

Shimano's Dura-Ace Di2 Front Derailleur is the brains of their whole Di2 electronic shifting system. There's an ultra-compact CPU inside the beautiful carbon body that actually monitors the position of both derailleurs, ensuring that shifting is super fast and incredibly accurate shift after shift. It also creates a front derailleur that moves to maintain clearance between the chain and cage no matter what chainring/cog combination you choose (no rubbing or trimming). Even more impressive and important, this is the quickest shifting front derailleur available meaning you'll never miss a shift again and will hit the right ring faster than ever. Thanks to no cables and housing to stretch, wear, or fail, you'll also love Di2's amazing durability and consistently smooth, silent operation.

These are a bit lighter than modern derailleurs, since the cable can only come from a single direction as opposed to modern dual pull models. The reinforced chain guide is high strength and stiff for improved shifting. Designed specifically for use with 9 speed chains. Weight: 123 grams Compatibility: Mega-9, accommodates 44-48 tooth large rings Feature: Special cross section increases Chain Cage rigidity for improved shifting response

The CeramicSpeed Oversized Pulley Wheel System has been proven to be the fastest pulley system in the world, providing energy savings starting from 2.4 watts over standard systems. The OSPW System for SRAM eTap is an industry leading product, chosen by many of the world's leading cycling teams and professional triathlete's. Featuring a 17-tooth upper and lower pulley wheel to provide absolute optimisation of the rear derailleur. The upper and lower oversized aluminium pulley wheels come fitted with either standard or coated CeramicSpeed Bearings.

Rapid rise for reverse shifting Shimano XTR M951 Rapid Rise rear derailleur