The meticulous engineering and overall design of the Di2 system not only streamlines shift performance to the touch of a button but also enhances longevity and precision at the same time. Di2 is a closed system, completely waterproof and sealed from the elements, its operation unaffected by the weather. It will function exactly the same in every condition you can throw at it. The wires and batteries are mostly housed in the frame, protected from the elements, meaning shift indexing won’t falter when the conditions get nasty. (Have a look at Mathieu van der Poel’s cyclocross bikes, which he trusts with Dura-Ace Di2 to deliver reliable, world championship-winning performance in harsh muddy conditions, season after season).