Apidura Aero Pack gravel race bags save 16W to go faster!
The fastest aerodynamic bikepacking bags in the world, really? Apidura’s drag-optimized Aero Pack system is designed to make gravel bikes faster. It saves Fat Pigeon racer Nol van Loon’s Ridley Kanzo Fast 16.66 watts at 40 km/h compared to no bags at all, and it helps carry all the nutrition and spares you need. Nol will need to take on Unbound Gravel this weekend.
Apidura Aero Pack System Aero Gravel Race Bags
We admit, when 3T first told us about airgravel six years ago, we were a bit skeptical. Was he going fast, slower, or slow but faster? In any case, the years since have shown that gravel enjoys aerodynamic advantages at all speeds – from aero gravel wheels to the most aero gravel tyres! We even had a nice AASQ discussion about air gravel last year.
Now Apidura has teamed up with Ridley Bikes and Hunt Wheels to create what they say is the “World’s Fastest Gravel Bike” to race Unbound Gravel this weekend.
Development of Aero Bikepacking bags
Both Apidura and Ridley had wondered how bags could not add drag to a gravel race bike, but actually make them faster. Baseline testing in the Bike Valley wind tunnel has shown that a conventional bikepacking setup can add up to 17.5W of additional drag for riders looking to haul race supplies all day (at a fairly conventional test speed of 40 km / h). That’s more than the gains you get with deep aero wheels, a wetsuit, or an aero bike over conventional setups. Apidura says that even a regular top-tube power pack added 4W of unnecessary drag in their wind tunnel tests, which many riders (including me) would have thought had minimal impact.
Those numbers aren’t a game-changer for multi-day bikepackers, but for fast gravel riders it could be a winning edge. #marginalgains
So, with the goal of making bags to make a gravel bike faster, Ridley identified areas on its “world’s fastest and most aerodynamic gravel” Kanzo Fast where bags could extend frame tube designs. aerodynamically profiled for smoother airflow on the bike. Then the Apidura Innovation Lab embarked on a back-and-forth iterative design development process – from the drawing board to the CFD to the prototyping shop and the wind tunnel, again – to create three small bags to make the Ridley faster.
Resulting Aerial Gravel Gains
According to Apidura, “The Aero Pack system was wind tunnel tested with Fat Pigeon’s Nol van Loon in the Bike Valley wind tunnel, finding a saving of 16.66 watts at 40 km/h – similar to going from box section to section wheels deep or loose clothing to a skinsuit. Even more impressively, the savings translated into low-speed performance, with the packs saving 2.4 watts at medium Unbound running speeds (32.04 km/h).”
Almost as an aside, but the biggest reveal to us… Apidura admits another Nol van Loon move saved it an additional 5.27W of average drag at that more realistic slower 32km/h speed . While the Aero Pack System bags are still in prototype stage and would only fit the large size Ridley Kanzo Fast, changing from a long-sleeved aero jersey with padded pockets to the already available $189 / €157 Racing Hydration Vest d’Apidura reduced drag twice as much as adding the bags did, at least at slower speeds. And the advantage increases at increased yaw angles (in crosswinds) where aero packs are less useful.
I guess, should I start carrying a runner backpack instead of a toptube bag? !
The Apidura Aero Pack system for this Ridley Kanzo Fast consists of three narrow aero bags – Aero Top Tube Pack, Aero Frame Pack and Aero Rear Pack. Each uses heat-sealed modified Hexalon fabric with a raised screen-printed dot design to smooth airflow – claimed to be 5.7W faster than their Racing Series’ standard Hexalon…so hopefully those- ci will all get a dotted update now too!
The bags use 3D printed plastic brackets that attach to the bike, but also ensure that there is no air space between the bag and the bike to create turbulence.
The Aero Top Tube pack is tiny at 0.4L and 37g light, designed to hide from the wind behind the steerer and stem with just enough room for gels or quick snacks. It does away with a zipper in favor of a flush closure with magnets inside. The small bag is mounted directly to the bolts of the top tube, and probably the first of this line that could be marketed. But it’s complex – Apidura says it takes 8 tools to craft versus just 3 as their average pack – so it would probably be quite expensive.
The Aero 2.5L frame pack is much more custom, designed to match the tube shape of that specific bike and using a 3D printed mounting bracket that required Ridley to drill holes in its carbon frame for direct attachment. The frame bag itself weighs only 170g, but its mounting hardware adds another 234g in this prototype. Like the toptube bag, the frame bag replaces zippers and flaps with a flush cut TPU opening with a magnetic flap inside to make it waterproof and dustproof, yet easy to access.
The Aero 0.8L rear pack feels like something out of a triathlon, with a similar goal of reducing air turbulence behind the seat tube. The 36g bag attaches with a 74g 3D printed bracket that replaces the seat post clamp cover and extends to the fender bolt on the seatstay bridge. The rear bag has a simple roll-top closure and internal stiffeners like other bags to retain its optimized aero shape no matter how you pack it.
(… but interestingly, not the most aerodynamic Schwalbe gravel tire.)
Apidura Aero Pack System – Availability, not yet…
Ross Pugh of Apidura Innovation Lab describes the project as only possible through the technology-driven collaboration between their team and Ridley. “Due to the data-driven design process, the packs are small and complex, creating new design and manufacturing challenges that we had to overcome. We were able to engineer some of the complexity by breaking down the challenges and using advanced tools and techniques like 3D printing to smooth out the transitions and attach the packs to the shaped tubes.”
At this time, the Apidura Aero Pack system is a “one-off concept currently”, but like other projects in their innovation lab, it is likely to inform revisions and updates to current products, and is an indicator of the direction they are taking on other projects.