Ridley has taken advantage of UCI rule changes with its new Dean Fast time trial bike to improve aerodynamic performance.
The Belgian brand claims the updated version of its time trial bike produces less drag due to a reduced frontal area and elongated tube shapes.
The Dean Fast comes with a mountain-bike style Universal Derailleur Hanger and can accept up to a 60T chainring in a 2x configuration.
We expect Ridley-sponsored men and women to race the Dean Fast in 2023 UCI World Championships time trials.
Drag reduction measures
The '3:1 rule' meant the length-to-width ratio of bike frame tubes used in UCI competitions could not exceed three.
UCI rule changes relaxed the ratio to 8:1, allowing manufacturers to deepen tube shapes into a more aerodynamic profile.
Ridley has capitalised on the relaxed regulations by elongating the head tube of the Dean Fast.
The brand claims this reduces the amount of turbulence that flows behind and causes drag.
Ridley says it has also benefited from the UCI easing restrictions on tube shape design.
The new hourglass shape of the head tube “strategically shapes airflow” and diminishes the frame’s front profile, according to the brand.
As before, the stem sits flush with the top tube, which is also claimed to reduce drag.
Ridley has applied a textured surface, similar to the dimples on a golf ball, to certain areas of the Dean Fast to improve aerodynamics.
F-Surface Plus technology, first used on the Ridley Noah Fast Disc, comprises small grooves which, by creating a little turbulence, cause air to flow closely to the surface of the frame.
This reduces wind resistance on the rider and helps them go faster for the same amount of power, according to Ridley.
The brand claims the Dean Fast’s PF30 bottom bracket further contributes to the frame’s sleek profile and aerodynamics.
Universal Derailleur Hanger on a time trial bike
SRAM introduced the Universal Derailleur Hanger to unify mountain bike derailleur hanger standards in 2019.
However, Ridley says the technology can benefit road bikes and has specced it on the Dean Fast.
Ridley isn’t the first brand to adopt the UDH standard outside of mountain bikes – the Specialized Crux and Ventum GS1, for example, both use the standard.
However, as far as we’re aware, this is the first time trial bike to adopt the UDH standard.
The Dean Fast’s bolt-on front derailleur hanger is removable and can be covered with a cap if the rider switches to a 1x setup.
There is one front derailleur clamp for 53-40T chainrings and another option for a 60-47T combo.
The Dean Fast is only compatible with electronic groupsets. Removing the provision for mechanical cable routing gave the frame designers and engineers more freedom, according to Ridley.
Multiple bottle cage mounting points
On the down tube of the Dean Fast, there are two bottle cage mounting points.
The higher position is designed to be used for training because it is easier to reach, according to Ridley.
The brand says the lower position is less accessible but more aerodynamic and therefore optimal for racing.
How was the Ridley Dean Fast tested?
Ridley says it used Computational Fluid Dynamics (CFD) to identify new designs that would minimise drag at 55 km/h – a very high speed for most of us, but one that is regularly attained in top-level time trials.
The brand tested the most promising designs in a wind tunnel at Bike Valley in Beringen, Belgium.
The winning frame design became the Dean Fast.
Sizing and geometry
The Ridley Dean Fast will be available as a frameset (including base bar) in small, medium and large sizes. Ridley will not offer the Dean Fast as a complete bike. Pricing is TBC.
Ridley claims the Dean Fast frame weighs 1,250g in size medium, the base bar 341g and the fork 460g.
Ridley says this gives riders the flexibility to customise the Dean Fast as they wish.
| S | M | L | |
|---|---|---|---|
| Saddle height (mm) | 790 | 790 | 830 |
| Seat tube length (mm) | 500 | 500 | 540 |
| Top tube length (mm) | 510 | 532 | 555 |
| Head tube length (mm) | 90 | 90 | 110 |
| Seat tube angle (degrees) | 74.5 | 74.5 | 74.5 |
| Head tube angle (degrees) | 71.5 | 72 | 72 |
| Chainstay length (mm) | 405 | 405 | 405 |
| Bottom bracket height (mm) | 75 | 75 | 75 |
| Wheelbase (mm) | 964 | 977 | 1,001 |
| Standover height (mm) | 763 | 767 | 786 |
| Stack (mm) | 495 | 499 | 518 |
| Reach (mm) | 373 | 394 | 411 |
