In Shimano's Dura-Ace, Ultegra, and 105 SC series brakes, there exists a "Dual Pivot Brake". It's a side-pull brake. These brakes have three arms that form the caliper. The arm nearest the bike (1) which is held in place by the pivot bolt serves as a mounting for the arm farthest from the bike (3). Between these two is another arm (2) held in place by the pivot bolt. Arm 2 works just the way the short pivot arm has always worked. Arm 3, holding the brake pad, has a pivot bolt half way between the traditional brake and the brake pad, which is fixed to arm 1. Using the dual pivot system Shimano has shortened the travel on the long arm. The brakes respond faster, remain centered, and require fewer adjustments.
These are the 7403, high end version of Dual Pivot Caliper. Both of the pivot points have thrust bearings to reduce friction and keep the caliper centered. The caliper has a rotating cam quick release (with click stops) so the brake can be used if your wheel is knocked out of true while riding. They use a low profile brake shoe and are easy to adjust. Each of the brake arm pieces and the brake shoe holder (with tire guide) is aluminum. Available in short reach only with Black brake hoods. The set comes with the Dura-Ace ST-7400 Dual Control aero racing 8 speed indexed shift/brake levers. These are the novel levers that permit you to perform indexed shifting on both the front and the rear derailleur with your hands still on the brakes. The shifting and braking system is designed so operation can be performed with your hands on the hoods or on the drop. It is certainly a faster system for shifting because your hands work faster in one place than they would moving to the down tube first, then shifting. Here's how they operate.
The left lever system has two levers, a large full hand size lever that both brakes and shifts the chain from the small to the large front chain ring. When your pull the large lever to you it activates the front brake, just as it the left lever always has. When you push the left big lever to the right it activates the front derailleur and moves the chain from the small to the large chain ring. Inside and behind this large lever is a smaller lever. When the small one is pushed to the right it moves the chain back from the large chain ring to the smaller one.
The right lever system also has two levers, a big one and, a smaller one inside and behind the large one. The large lever, when pulled to you, activates the rear brakes just as the right lever always has. When you push the large right lever to the left it advances the rear derailleur from a small rear cog to a larger rear cog. A full throw to the left of the large right lever will advance (with clicks for indexing) the rear derailleur up to three cogs at one time, or you can accept less using a partial push to the lever. The inner smaller lever when pushed to the left shifts the rear derailleur from a larger sprocket to a smaller one. Each left push on the smaller lever shifts the rear changer down just one cog.
It must be understood that this increase in shifting performance comes at the cost of adding weight, but it's in an area of the bike where it's consequence is marginal. Wouldn't it be nice if some bike parts were, say, made of magnesium? (hint). The weight for the complete brake/shifting set is 1258 grams (calipers-425 grams, leverset-557 grams, cableset (including shift cables, new downtube cable stops, since your down tube shifts will be gone, and aero shrouds for both cable sets)-276 grams). Do not be put off by the weight, this is remarkable system!!
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Shimano Dura-Ace 7402 Side-Pull Brakeset
