Apidura has finally launched its Aero System bags – comprising a Top Tube Module and Frame Module designed to work in tandem for an aerodynamic advantage.
According to Apidura, the bags “fill in the shape of your bike” to trick the wind, while offering onboard storage.
All this is said to bring an average 5W saving, when tested at 36kph and 44kph (at six different yaw angles, too), which Apidura calls “realistic race speeds”. After all, 36kph was the winning average speed at Unbound 2024.
The bags are available in two sizes – S/M and L/XL, with Apidura recommending the smaller bag for bike sizes up to 56cm and the larger system for up to 61cm bikes.
The Top Tube Module has a 0.4l capacity and the Frame Modules are 1.5 / 2.8l, depending on the size.
Apidura stresses you should buy the system based on your frame size, rather than the bag capacity – the larger Frame Module is much taller than the 1.5l variant, for instance, to ensure it fills the gap at the head tube junction.
The Aero System retails for £188 / $278 / €218 / AU$378.
Forging the (aero) path
The Aero System began life as ‘Project Breakaway’, a collaboration between Apidura, Ridley and Hunt to build the “world’s fastest gravel bike”.
Apidura says it carried out CFD analysis and wind-tunnel testing at the Bike Valley Wind Tunnel in Flanders, Belgium, to arrive at the system’s ultimate shape.
We first spotted prototype Apidura bags being tested at Unbound 2022 and saw them again on Piotr Havik’s bike at Unbound 2024 – but the final product has some obvious design changes from these earlier prototypes.
Apidura says the shape of the bags “smooths airflow around the bike, reducing drag and making the rider faster for the same effort”.
The brand has gone to great effort to make sure there are no gaps between the frame and bags.
Apidura has also used what it calls ‘Transfer Panels’ and ‘Skirt’ for each bag's body so they more closely hug the frame.
The ‘Transfer Panels’ are channels positioned behind the Top Tube Module, so it hugs the back of the stem (rather than using a conventional strap that secures around the stem or headset spacers). Therefore, there are no gaps between the head tube, top tube and down tube where the Frame Module sits.
The Top Tube Module also uses a magnetic entry, rather than a zip, which Apidura says is quicker.
The Frame Module is slightly more conventional, using a traditional zipped closure, and there’s a loop on the inside for storing a tubeless plug kit or a small gravel pump, such as the Wolf Tooth EnCase.
Fastening both bags together to the frame are ‘Hypalon Load Straps’, which are more svelte than the thicker straps found on the brand’s other bags, with a cam lock to adjust the tension.
The Frame Module also features a more conventional down tube strap, which can be trimmed to length to suit your frame.
Silicone bands secure the Frame Module around the head tube into specific hooks, which are unique to the Aero System. Apidura says this “amplifies the smooth air generated at the front end” and boosts security.
Apidura claims the Aero System Bags in an S/M weigh 305g together, but I weighed them at 297g. The L/XL variant is claimed to weigh 335g.
Apidura Aero System first impressions
I’ve been testing the Apidura Aero System for a week before today’s embargo, logging four rides totalling just over 200 miles / 320km.
I fitted the bags to my Niner RLT 9 RDO and the first thing I did was apply frame protection tape to any areas where the bag would contact the frame because Apidura doesn’t make any claims about the bags not rubbing the frame.
If you follow Apidura’s instructions, fitting is relatively straightforward. For a cleaner look, you can position the cam locks so they are all on the non-driveside. To do this, I had to remove the straps and reverse their position, which proved quite fiddly.
All in, I’d say it took me about 20 minutes to fit the system, including applying the frame protection tape.
The Top Tube Module is very small – I was able to store two energy gels and an energy bar in there. The bag is too small to fit a phone – and nor should you, because Apidura doesn’t claim it to be waterproof.
The Frame Module is much more generous, and here I stored an inner tube (suitable for a 50mm tyre), tyre levers, a multi-tool, an electric mini-pump and three more energy bars, with a little room to spare.
On my maiden voyage with the bags, it was also my first time trialling a set of gravel bike tyres for an upcoming group test – I barely thought about the bags while I was riding, which is always a great sign.
But early into my second ride, a humid 113km Chiltern hillfest extravaganza, I headed down a particularly rough descent and, towards the bottom, noticed the Top Tube Module contacting the side of my knee, having completely lost its tension.
This was rather frustrating, but I’m going to chalk it down as a one-off because since I readjusted it, I’ve had no problems – and that includes testing the bags down some even gnarlier descents.
I’m particularly impressed by the Frame Module – there’s ample storage for longer rides, it’s easy to use and is unfussy.
My feelings about the Top Tube Module are more mixed, although I appreciate I’m not a gravel racer chasing minute aero gains.
There’s simply not enough storage, and for my preferred riding (long-distance epics and bikepacking), I’d almost rather store the three gels or bars in my jersey pocket – sacrilege to the aero gods!
That said, I fully understand that would cause more drag and, as Apidura says, the Top Tube Module is something to fill in the gap.
If it makes a bike more aerodynamic by running it, I suppose that’s three fewer items in your pocket.
I asked Apidura if it experimented with testing a Top Tube Module with the same length as the Frame Module for more storage and whether that had a negative effect on aerodynamics.
Ian Carter, Apidura’s head of brand and marketing, replied “racing in single days is so tight that there’s a lot of sprinting” and that feedback from riders was “they didn’t want to have their knees contact the bag when sprinting”.
However, Carter referred me to Apidura’s ‘constant forward progress’ brand philosophy and suggested that its approach to continual development means it may choose to “expand the line of product within this range in the future”.
Apidura Aero System early verdict
Truth be told, I couldn’t give a flying fruitcake about how aerodynamic something is.
However, I fully appreciate that it will matter to some, and in the heat of battle at races such as Unbound, if a 5W difference is the difference between first and second place, then it’s a benefit worth chasing.
Apidura’s Aero System is a very exciting release – this is uncharted territory and I’m eager to see where the technology is headed next.
I can’t wait to find out what kind of other products Apidura brings out with this technology, or how it inspires other manufacturers to react.
