Do wind-tunnel tested bike bags help make this Ridley the world's fastest gravel bike?

There was plenty to see at the Unbound Gravel race in Emporia, Kansas, this year. 

With a record 4,000 registered racers in attendance as well as their support crew, family, friends and bike fans, the small town in the middle of the U.S.A sure lived up to its nickname of ‘Gravel City’.

WIth such a concentration of potential consumers in one place, hundreds of brands took the opportunity to showcase their gravel offerings over the course of a two-day expo. 

Schwalbe launched their new tires G-One RS tires, three-time World Champion Peter Sagan was there to show off Specialized’s hyperlight Crux which debuted last fall, but Ridley, Hunt, Apidura and Fat Pigeon were there to showcase something else entirely. 

The quartet of brands partnered up to produce, what they claim to be, the fastest  gravel bike in the world or rather, a complete gravel race ready setup in which the bags actually make the bike faster.

The ‘world’s fastest gravel race bike’, made even faster

Gravel races tend to be long endeavors that take place in remote locations. Riders are expected to be self-sufficient in fueling themselves and fixing flat tires and mechanicals. As such, riders rely on paired-down touring or bikepacking bags to carry their food, tools, spares and other essentials. 

But like in every other racing discipline, the goal is to complete the course as fast as possible to beat others to the line. 

To that end, we’ve been seeing the emergence of increasingly light race-specific bikes and deeper wheels, the use of aerobars, slim hydration vests and other gear aimed at providing any racing advantage possible, be it in terms of weight or aerodynamics.

While brands like Specialized and Cannondale initially focused on comfort and suspension, Ridley was keen to venture down the path of superior performance thanks to aerodynamics. The Kanzo Fast was launched back in 2020, which is a gravel adaptation of its Noah aero road bike. 

Ridley engineers spent hours in the wind tunnel and on gravel roads to produce a pure-bred gravel racer that is highly responsive and faster than any other gravel bike on the market. Yet all that sleekness and all those aerodynamically optimized shapes lose their effectiveness when laden with bags. 

Enter bike bag specialist Apidura. A leader in bikepacking luggage, the British company was also wondering if its bikepacking bags couldn’t be designed to avoid drag and help riders reach their destination faster. 

And so into the Bike Valley wind tunnel they went. Initial testing by the two brands found that a poorly optimized bikepacking setup could be costing racers up to 17.5 watts at 40km/h, thereby offsetting any advantages gained from an aero bike, deeper wheels or skinsuit. Even a small food pouch on the bars could be adding four watts of drag at 40km/h. 

While this is not something multi-day bikepackers would concern themselves with, it can make a difference at a career-making race like Unbound, Belgian Waffle Race or SBT GRVL.

Could bags be designed to have less drag? Better yet, could they make a bike faster?

When thinking about bike bags in the same fashion as fairings or airfoils, the bags could in fact help create a faster overall system. 

After six months of development, the ‘Aero Pack System’ was put to the test with Fat Pigeon’s Nol van Loon in Belgium’s Bike Valley wind tunnel. Uniquely integrated with a large-sized Ridley Kanzo Fast bike frame, the bag system consists of a seatpack, a frame bag and a top tube bento box. 

The top tube bag is the smallest Apidura has ever made and hides in the silhouette of the steerer and stem while still providing enough space for gels or other small food items. 

The frame pack is attached using a custom 3D-printed mount to smooth the transition from the frame to the pack, and bolls directly to the frame. Similarly, the seat-stay pack also has a custom frame-specific, 3D-printed mount that bolts to the bike frame’s mudguard mount.

The bags feature a new opening made of TPU fabric and magnets that not only provides easy access, it also sits flush and keeps out the dust and water.  

Even the bag’s fabric design was aerodynamically optimized. The dotted pattern is not for aesthetics. Instead, this new design proved to be 5.7 watts faster than Apidura’s standard Hexalon fabric at 40km/h. 

The overall result? A 16.66 watt savings at 40km/h — this is similar to upgrading from shallow wheels to deep dish aero wheels, or from going from street clothes to a skinsuit. 

Even at a more realistic endurance speed of 32 km/h, the packs yielded 2.4 watt savings.  Adding an Apidura Racing Hydration Vest to Van Loon’s setup further improved this to 7.67 watts saved.

Most importantly, these bags needed to remain practical so Van Loon could carry the necessary food, tools and equipment to complete the 200-mile (322k) event, which he did in 11:20:57 with an average speed of 28.38 km/h despite the rather epic weather conditions.

Apidura’s Chris Herbert told Cycling Weekly that this was a pure concept project, and the actual Aero Pack System will not be for sale as is. However, the lessons learned and technology gained will surely make their way in forthcoming products.

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The Complete Bike Build

Frame: A large Ridley Kanzo Fast

Cockpit: Ridley’s integrated stem and handlebars (no wire in sight!) and clip-on adapters for PRO aerobars

Groupset: Shimano GRX

Wheels: Hunt 42 Limitless Gravel wheelset wrapped in Vittoria Terreno Zero tires