Cervélo has revamped their top-of-the-line aero road frameset for 2015. The S5 has been tweaked to be stiffer, more aero, more comfortable, fit better, and the overall weight has been reduced.

Because aero is so important, they made sure that the new S5 is more slippery than the old S5. The savings are to the tune of 16.9 watts at 40kph. That to an already fast frameset. They accomplished this in several ways. They widened the front end, finding that a wider lower headset bearing, the 1 3/8" found on the rest of their road line, is not only lighter and stiffer, but faster when combined with a fork crown that integrates with the dropped down tube and smoothes out the air behind a standard front brake. The legs are also wider, and this gave them the added benefit of allowing the rider to fit 25mm wide tires. The down tube has also been reshaped, with better shielding for the water bottle and cage people will inevitably put there. For folks who want only a single bottle, using the lower mounts will make it more aero still.

Another component in going faster is increasing efficiency. The S5 does this with greater stiffness. The bottom bracket area has seen stiffness increase by 6%. This translates into more leg power going directly to drive the cassette. The head tube, thanks to the new tapered shape and wider profile, is 35% stiffer. The fork is now laterally stiffer by 17%. These features make steering, turning, and even out-of-saddle efforts easier.

The geometry has been modified for better fit. Specifically, they've adjusted tube lengths and angles so that the dimensions of the S5 in all the sizes match their other road bikes. The big take-home is that the head tube is lower than the previous iteration, which means people won't be sizing down just to get their bars in the position they want.

If you recall the older S5, it had a two-position sea seat post. One offering 40mm or 0mm of offset. The new single-position post offers 20mm of offset. The two-position post comes on the smallest frame size as standard equipment and can be found as an aftermarket improvement if it would suit your needs better.

Cervélo also worked on the small things to make sure they left no aspect of the bike without improvement. The BBright bottom bracket shell was utilized to maximize tube shaping opportunities, for stiffness, aerodynamics, and weight reduction. The cable routing has been improved for easier installation, less weight, and less friction when using mechanical shifting and braking. To further this, the rear brake cable runs in a straight line in the top tube. And the under-the-bottom-bracket cable guide is now their excellent reduced friction guide, identical to what you'll find on the rest of the road line. And the routing through the right chain stay is straighter, and comes out of the dropout at a better angle for running the cable housing to the derailleur.

The bottle mounting has not only been improved on the down tube, but also on the seat tube, with the position lower than before, making it easier to access bottles, even mount extra large bottles, on the small sizes.

The Cervélo S5 aero road frameset goes beyond the fastest aero road bikes for a new definition of fast.