Ribble has announced the Ultra, a new aero road bike with an aggressively aero-optimised frameset and a novel integrated handlebar design with “wake generating” bulges on the tops.
These bulges – which are claimed to manipulate the airflow over the rider in order to reduce aerodynamic drag compared to a standard aero handlebar – are unlike anything we’ve seen before, and Ribble claims the gains are significant.
With a brief to “make the most aerodynamically advanced frameset in the world”, Ribble has invested three years of intensive CFD (Computational Fluid Dynamics), wind tunnel and real-world development. The result is the Ultra, which has deep, truncated aerofoil tubes throughout, high levels of integration, and is specced with aerodynamic wheels and components on all builds.
As for how fast it is, Ribble claims the Ultra offers an “11.6 watt saving at 22mph across the average of 5 and 10 degrees of yaw” over Ribble’s Endurance SL Disc road bike, which, Ribble says, makes it “75.1 seconds quicker over 40km”.
To ensure it’s as good for amateurs as it is for the pros, Ribble says the Ultra has been aero tested at two speeds – 22mph (10 metres per second) and 29mph (13 metres per second) – with time gains being more significant at the slower speed.
As always with Ribble, prices are very competitive, starting at £3,199 for a build equipped with Shimano 105 R7020 and Level carbon wheels.
Return of the aero bike
As you’d expect, the extensively aero-optimised frame and fork feature all the hallmarks of modern aero road bike design.
The frame has deep, truncated aerofoil tubes, a narrow head tube and, of course, dropped seatstays.
The lower section of the down tube also flares out dramatically to manage the airflow around a water bottle – the assumption being the vast majority of riders will typically carry at least one water bottle when riding.
The down tube is similar in approach to that of Cannondale’s SystemSix aero bike, although the taper of the aerofoil near the head tube is more dramatic on the Ribble.
The fork was subject to extensive development too, with multiple different aerofoil profiles, tube depths and stance widths tested.
Although UCI rules allow for fork blades up to 80mm deep, Ribble settled on 68mm×15mm fork blades (having also tested 56mm blades). Though Ribble’s testing showed the 80mm fork blades were more aero below 10 degrees of yaw, performance dropped off dramatically at wider yaw angles.
The non-driveside fork leg is also shaped to hide the front brake caliper from the airflow, improving the airflow over a component that isn’t typically optimised for aerodynamic efficiency.
The seatstays were also placed in line with the fork blades, to further reduce their drag at low yaw angles.
To recap, yaw is “the angle of attack of the wind on a cyclist”. A straight-on headwind is a yaw angle of 0 degrees, and crosswinds have positive or negative values depending on which side the wind is coming from. The faster you ride, the lower yaw angles you’ll typically experience, and vice versa.