Dura Ace 7900

Di2 is Shimano's new, flagship groupset. Combining Dura Ace 7900 ergonomics with the performance of an electronic shifting mechanism sets this apart. Di2 is the best groupset that I have ever ridden, but then for this money so it should be.

The dual pivot callipers have a modified arch which, Shimano say, gives you a more linear response. Possibly – although you’d have to run them alongside the old model and concentrate really hard to notice much difference there. More significant is the brake block compound that provides significantly stronger power in both wet and dry conditions with a single trigger finger, giving you the confidence to ride faster into bends and brake later.

The design of the link has been improved so you get a slightly lighter action in both directions. But the most noticeable difference here is that you no longer get a trim option – the small movement to adjust the plate position without moving from the big to the small chainring. The wider link means you don’t need it, which makes life just a little easier. You can even – if you’re some kind of crazy anarchist – run the chain from big chainring to big sprocket and there’s no rubbing on the front mech.

There are a couple of big changes out back. First, you get a carbon pulley plate that brings down the weight (16g overall). Second, the new rear mech is compatible with cassettes up to 28T. The total capacity (the tooth difference between the two chainrings plus the tooth difference between the biggest and smallest sprockets) is now 33T – so you’re unlikely to feel the need for a triple.

The hollow forged alloy crank (after flirting with carbon, Shimano Dura-Ace cranks are now fully alloy again) is matched up with a hollow outer chainring to produce a crankset that’s a tad (15g) lighter than before. It’s also said to be 20% stiffer although, in use, you’ll do well to notice. Even if you’re a big rider pushing a big gear, the difference is tiny – but, hey, everything helps so we’re not going to argue.

The new integrated brake and gear levers have been totally redesigned. For a start, the brake levers are carbon to drop a few grams (the complete units are 40g lighter) and add more sex appeal. Then there’s the shape of the bracket body: you get a flatter top section with less of a scoop downwards when you’re on the hoods. We wouldn’t say they’re necessarily more comfortable, just different from before, and definitely more Campag-esque.