The Shimano Di2, the Digital Bike Revolution

The Shimano Di2, let's get that name out of the way first. Di2 stands for Digital Integrated Intelligence, and Shimano's flagship road group-set definitely lives up to its name. Those Shimano tech guys are one smart bunch of people.

In development for more than five years, Shimano's eagerly awaited electronic group-set has been the subject of many conversations on by voice or in forum arguments. But at first glance, its eventual may have disappointed some. The Shimano Di2 is not, as you might have first thought, a wireless, super-duper system that' s clever enough to think itself into the correct gear while you just pedal.

Correction – the Shimano Di2 is super-duper. But initial worries that it looks just like a normal group-set, with its cables in all the same places, are soon allayed. True, it isn't wireless, but electronic wires replace traditional cables and outdo them in performance no end. While cables stretch with use and misfire after being affected by water and dirt, the Shimano Di2' s electronic system gives you super-fast, crisp, clear shifting every time. In fact, changing gear is an absolute pleasure. Even without taking into account the ridiculously satisfying electric buzz that the system emits with each shift, the perfect-every-time changes really do allow you to concentrate more on your riding, while at the same time encouraging you to shift more often.

Don't get carried away, though – you'll run that battery out. Or you will? We've been told that it's good for around 800km or riding – loads, in other words.

Shimano's official line is a full charge should get you 1,000 to 2,000km of riding but it obviously does depend on how often you shift gear. Certainly pro team mechanics we've talked to in the past about electric gear systems haven't flinched when it comes to this new technology, telling us it would simply be a case of charging the battery overnight, like with a mobile phone or notebook, and a full charge only takes two hours anyway. Weight-wise, it's a mere 60gram heavier than Shimano's 7900 Dura-Ace group-set.