For cyclists who want every possible advantage, Campagnolo's Record 11 Rear Derailleur shaves 13 grams off of the already low weight of the Chorus model a feat that's achieved without compromising the buttery shifting and durable reliability that Campagnolo is known for. Record's low weight, ceramic bearings, and price make it the benchmark against which all other rear derailleurs are measured. The brains of the derailleur are the cross section springs, which have rectangular cross sections for an increased return load. In conjunction with the new Record shifters' cable pull ratio, this translates to faster, more precise shifting in both directions. The parallelogram's motion as you shift across the cassette has also been revamped for 2015. It corresponds to the size of each cog, so the top pulley stays the same distance away from the cassette whether you're using the crit spec'd 11 23 or the all terrain 11 29 cassette. This keeps the chain seated securely on the cassette at an angle of engagement that transfers maximum power into propelling the bike forward. It also reduces wear on your chain and cassette, which is a huge plus considering the premium you pay for Record. The parallelogram and cage are made with carbon, while the upper and lower bodies are made from a technopolymer that's lighter than metal but can still stand up to any abuse from the elements or the occasional user error read: crash. The Record model's pulleys feature an upgrade from Chorus, using lightweight polymer. These weight reductions are further boosted by the cutouts in its parallelogram. It also uses ceramic bearings instead of Chorus's steel, though it lacks the titanium internals of its Super Record counterpart. The Campagnolo Record 11 Rear Derailleur is only compatible with 2015 Campagnolo Super Record, Record, and Chorus drivetrain components. Compatibility can be confirmed by matching the letter on the body's underside with the corresponding markings on your other drivet...