While the prior rim-brake Dean Fast appears to remain in the line as a complete bike option, this all-new Ridley Dean Fast Disc gets a lot of aero updates and (better late than never) switches to disc brakes. And, it will only be sold as a frameset at launch.
Using CFD, they “identified new designs that would minimize drag at speeds around 55km/h”, or about 34.2mph. Yes, that’s wicked fast, but it’s about the average speed of the 10 fastest Tour de France Individual Time Trial performance (according to this website). Which means top riders are often going faster than that, and let’s be honest, bikes like these are made for the top team riders first and just happen to be for sale to the rest of us.
The biggest change comes from taking advantage of the UCI’s new 8:1 length-to-width tube profile rules, allowing for dramatically longer tube proportions than the prior 3:1 rule.
Ridley applied this in “compensation triangules”, which is another new allowance from the UCI, giving this bike an extended head tube that creates a blunt point at the front, then runs deep behind the steering axis.
That shape blends into the fork’s crown, and the stem is nestled into the head tube for a further streamlined frontal area, flowing directly into the top tube.
Ridley’s other trick, called “F-Surface”, which they’ve applied to other bikes in the past, include dimpled surfaces (similar to a golf ball) and indented grooves at key points on leading edges. Combined, they create smoother laminar airflow, which keeps the air flowing smoothly over and off of the tubes and minimized eddies and swirls that cause drag.
Keeping with trends, it fits up to a 700x32mm tires, though it was designed around 700x28s.
And it gets a UDH rear hanger, helping future proof it for whatever drivetrains may come.
The front derailleur mount bolts on, letting you remove it for 1x setups to further reduce drag, and two clamps come with the bike – one for normal chainring combos up to 53/40 and one for monsters fitting up to 60/47 combos.
It’s designed for electronic drivetrains only, with no accommodation for mechanical shift cables. The downtube has three bolts creating two bottle mount positions, plus one set on the downtube.
The included base bar has mounts compatible with most aero extensions and elbow rests, letting you add your favorite setup.
The frame weighs a respectable (for a TT bike) 1,250g in size Medium, with a 460g fork and 341g base bar. Available in S/M/L sizes for $4,999.