In 2009, Shimano launched the Dura-Ace Di2, the first electronic derailleur in series production - and triggered a small revolution in bicycle technology. A cheaper Ultegra version soon followed, and competitor Campagnolo followed suit in 2012 with three electronic groupsets. A trend started rolling. The new way of shifting is still very expensive - complete bikes with the cheapest versions cost at least €3,000. But for technology freaks and the professional peloton, it has become indispensable. The advantages are obvious: no lever travel, hardly any operating force - shifting gears at the touch of a button is more convenient than ever before. On time trial bikes there are extra buttons on the basic handlebars, on road bikes there are additional switches for the lower and upper handlebars.
Further advantages are recognisable at second glance: the Bowden cable, previously the clear weak point in the mechanical system, has been eliminated. High operating forces or inaccuracies due to elongated, worn or dirty cables are now a thing of the past, and there are fewer restrictions when routing the cables. The maintenance costs - frequent riders and winter cyclists sometimes have to replace shift cables annually - are also reduced and at least somewhat relativise the high surcharge. The catch is the dependence on electricity. A lithium-ion battery provides the energy for the gear changes. And even if it lasts a very long time for its purpose, it should not be completely forgotten, nor should the charger. Because without power, nothing works, the engaged gear is then fixed. A defect in the electrical system can also cause major problems. Since the Di2 has been on the road, we are only aware of a few isolated cases in which a part has failed - in our opinion, the technology is robust. However, you can't usually repair a fault yourself, and you won't get very far by dismantling the parts anyway. Even the diagnosis is difficult; it may just be possible to determine which part has a fault without help. We also had to send in the Ultegra Di2 test group of the TOUR editorial team once because the battery discharged itself for inexplicable reasons.
After just four years, the new version of the Dura-Ace Di2, number 9070, now follows. The mechanics are based on the Dura-Ace 9000, whose most important innovations are on board. These include eleven sprockets on the rear wheel - again on a par with Campagnolo -, the newly designed brakes and the crank design, whose bolt circle accommodates all chainring combinations. The Dura-Ace 9000 has once again raised the bar for mechanical shifting groupsets; above all, the outstanding brakes, the operation with short travel and low forces and the impressive shifting behaviour have made a lasting impression (see test in TOUR 11/2012->).
In the PDF download you will find the test results of the Shimano DUra-Ace Di2 as well as an overview of the electronic and mechanical groupsets from Campagnolo, Shimano and Sram.
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