S5 | Ultegra Di2, Ultegra C50

In pursuit of speed, everyone wants to try different positions to find their most aggressive fit. The S5's iconic V-stem not only inspires confident handling at high speeds, it's now also remarkably simple to dial in your perfect set-up. All the necessary spacers come with the bike, and there’s now only one bolt length, reducing complexity and making the system 53g lighter in the process.

Wider wheels and tires are faster aerodynamically, and more comfortable to boot. S5 comes specced with 28mm tires but has clearance for up to a 34mm (measured) tire. The frame is optimized to complement the wider Reserve 52/63 turbulent aero wheels. In addition to the handling benefits, this saves over 5 watts compared to the previous Reserve wheelset.

The UCI’s new regulations on aerodynamic design allowed us some additional room to deepen our aero profiles and squeeze 65 more grams of drag performance out of what is already the fastest aero bike on the market. You’ll notice a deeper head tube and BB area, and more aggressive shaping on the trailing edges of the tubes. Since the new S5 is only compatible with electronic shifting, we were able to tidy the dropout a bit, and update the shaping all over the bike.

We’ve improved the comfort of the handlebar, and tweaked the shape to get a perfectly flat bar-to-hood transition. We now use a two-bolt interface that allows for infinite tilt adjustments between 0 and 5 degrees.