The new Shimano Dura-Ace series, due October, has combined all of its engineering resources with the latest technology to develop a groupset that will benefit professional riders, as well as road racing enthusiasts. Besides offering a further improved performance and an attractive design, the weight is reduced significantly.
The seventh generation Dura-Ace group introduces revolutionary technology into the road-racing scene. Highlight is the Hollowtech II crankset that combines an attractive aerodynamic design with remarkable weight saving and completely new engineering features.
This high tech beauty is developed out of thin walled, hollow forged aluminum and features some novelties in road racing technology. The outer chainring for example is hollow which saves weight and makes it 20 per cent stiffer at the same time for an optimal power transfer.
There is a wide choice of FC-7900 chainring combinations: 53/42T, 52-39T, 53/39T, 54/42T, 55/42T and 56/44T. Crank arm lengths: 165 – 180mm with 2,5mm steps. Also a Dura-Ace compact crankset FC-7950 is available with a 50/34T chainring combination. The chainring teeth have been redesigned for an improved chain contact to improve power transfer. Furthermore, the bottom bracket features improved sealing for smoother rotation and longer durability.
This crankset weighs 725 grams including bottom bracket. This is 15 grams lighter than the current Dura-Ace crankset FC-7800. Rigidity remains the same.
Dual Control Levers
The new Dual Control Levers show the importance of state-of-the-art technology with regard to performance enhancing design. The lever blades are made of multiple carbon layers, finished with a unidirectional carbon fiber top layer with a special coating. This advanced technology ensures the best performance in terms of rigidity, durability and lightweight design.
Shift cables are hidden under the handlebar tape without sacrificing performance. This was made possible by the development of a new internal mechanism in combination with new PTFE coated inner cables.
The Dual Control Levers have a reach adjustment mechanism that will better accommodate smaller hands and a wider assortment of bar bends. Furthermore, the shift lever has a 20 per cent shorter stroke for faster shifting. The hoods have an ergonomic design for increased comfort, even at long distance rides.
The shifters feature integrated buttons on top of the hoods to operate the new wireless Flightdeck computer without the need to take the hands of the handlebar. Flightdeck measures data such as heart rate, altitude, inclination, cadence, gear position and more. It works with coded wireless signals that prevent interference from other electronic units. The new Flightdeck computer can be used to make a wireless connection with a PC to analyse riding data (software is included). The Dual Control Levers are over 40 grams lighter than the current version at 378 grams per pair.
Besides Dual Control Levers, also new bar end shifters and down tube shifters will be available to match the new Dura-Ace. A carbon brake lever BL-TT79 for aero handlebars will be available for time trial and triathlon usage.
The new Dura-Ace chain CN-7900 carries a lot of innovative technology. It has an asymmetric design and features redesigned outer plates to reduce the chance of chain suck. Also the inner plates have been redesigned for an improved contact with the cassette sprockets. The result is smoother shifting even under high load, for example when climbing or sprinting. Furthermore the chain runs smoother and is more silent than its predecessors and the new design allows a higher durability as well.
CN-7900 can be mounted with a reusable quicklink SM-CN79 that can be (dis)connected without using any tools. This quicklink is compatible with the other Shimano ten-speed chains as well. Also a normal connecting pin can be used. The chain has been developed with hollow pins and perforated inner plates to make it lighter. Weight of this chain is 252 grams, which is almost 30 grams lighter than the current version.
The rear derailleur has a wide gear ratio and can be used with sprockets of maximum 28 teeth. It is compatible with the use of a compact crankset without the need for a medium cage derailleur. It has a full carbon pulley plate and a carbon/resin composite P-body that helps to reduce the weight to 166 grams.
The front derailleur has a lightweight design and an optimum spring tension for feather light downshifting. Trimming the outer chainring is no longer needed to allow a better concentration on the ride. The efficiency has been improved by using a stiffer and solid wide link design. Weight is only 67 grams.
The brakes feature new compound brake shoes that doubles the brake performance in wet circumstances and improves stopping power in dry weather by 20 per cent. These new brake shoes feature a longer durability as well.
The brakes have been developed with an enhanced brake arch proportion for an increased linear response. A lower cable stopper ensures a better cable routing and reduced cable friction. The Dual-Pivot caliper brakes feature also a spring tension adjuster and adjustable toe-in brake shoes The dual pivot bolt and center bolt as well as the inner cable fixing bolts are made of titanium for an optimised lightweight design of 293 grams per set.
Shimano has developed a super lightweight yet very rigid aluminum cassette sprocket carrier. Also the separate sprockets have been redesigned for more robust shifting performance and to save weight. This ten-speed Hyperglide cassette will be available in a wider variation of combinations: 11-21T, 11-23T, 11-25T, 11-27T, 11-28T, 12-23T, 12-25T, 12-27T. The four biggest sprockets are made of titanium. Weight is 163 grams (11-23T).
The hub and freehub have an increased rigidity that improves rotation even when the quick release is tightened strongly. Furthermore, they have been developed with a completely new bearing adjustment system that enables easy manual adjustment without the use of a cone wrench.
More info at http://www.dura-ace.com