Apidura Aero Bolt-On Long Top Tube Module
The Apidura Aero Bolt-On Long Top Tube Module is a completely strapless, aero-optimised long top tube pack that bolts to your top tube mounts and adds carry capacity for long, fast days in the saddle. It holds 0.8 L, weighs 120 g, and can be used on its own or with the Aero Frame Module as a complete watt-saving system.
Why an aero bolt-on top tube pack – and why this one
Air flowing over the stem leaves a low-pressure pocket directly behind it, which causes drag. A conventional strapped top tube bag can make this worse, and straps can shift or leave gaps. The Aero Bolt-On Long Top Tube Module addresses both:
- It turns a drag zone into a smooth surface. Transfer Panels bridge the gap between the stem and the top tube, so oncoming air flows smoothly across the front of the bike instead of getting trapped.
- It sits flush, with no straps. Two M5 bolts anchor it to the top tube mounts; a centre channel in the base flexes around the mounting points and pulls the module flush for a gap-free fit.
- It stays rigid along its whole length. Full-length carbon fibre reinforcement and an internal HDPE frame keep the pack stiff and integrated.
- It lines up with your stem. 64 mm bolt spacing and 5 cm of fore-aft adjustment allow precise alignment with the rear of the stem – essential for maximising aerodynamic performance.
- Your kit stays dry. RF-welded seams and a full-length waterproof zip, opened with one hand on the go.
Who is it for?
- Competitive gravel racers who need to carry a bit more while keeping a clean, secure, aero fit.
- Fast road and endurance riders who want food, gels and tools within reach without stopping.
- Riders with top tube mounts who prefer a strapless setup.
Key features
Easy access
A fully waterproof zip allows one-handed access on the go.
Stem integration
Transfer Panels designed to conform to the stem for aero-optimised integration.
One system, your setup
Three top tube modules and two frame modules to mix and match into the aero setup that works for you.
Knee clearance
The slim profile reduces the chance of knee rub when sprinting.
Carbon stability structure
An ultralight carbon plate and high-modulus internal rods for pack-length rigidity and an integrated fit.
Made from Hexagrid
An ultralight, high-strength nylon grid laminated with TPU for a minimalist yet structured material.
Materials & technology
- Hexagrid – an ultralight, high-strength nylon grid laminated with TPU for a minimalist yet structured material. PFA- and PFC-free.
- HDPE – high-strength, rigid reinforcement boarding with good shape recall to avoid deformation.
- Aero optimised – actively improves the aerodynamic performance of bike and rider.
- Ultralight – minimal design and lightweight materials for optimal weight-performance.
- Wind tunnel tested – the Aero System is validated through wind tunnel testing.
Specifications
| 0.8 L (TSL) | |
|---|---|
| Capacity | 0.8 L |
| System weight (with Aero Frame Module) | Medium: 325 g; Large: 355 g |
| Storage | Single main compartment |
| Closure | Full-length waterproof zip |
| Attachment | 2 × M5 hex-headed bolts to top tube mounts (64 mm bolt spacing, 5 cm fore-aft adjustment); flexible centre channel in the base for a gap-free fit; elastic tensioner around the stem draws the Transfer Panels inwards |
| Structure | Full-length carbon fibre reinforcement; internal HDPE thermoplastic frame |
| Waterproofing | Seam welded (RF-welded watertight seams) |
| Visibility | Reflective graphics |
Care & maintenance
- Lubricate zips – clean and lubricate regularly with silicone- or petroleum-based grease.
- Hand wash only – use dish soap and a non-abrasive sponge, dry flat. Do not machine wash or tumble dry.
Frequently asked questions
How does it improve aerodynamics?
Air flowing over the stem creates a low-pressure pocket directly behind it, which causes drag. The module's Transfer Panels bridge the gap between the stem and the top tube, filling this space so that air flows smoothly across the front of the bike – reducing drag and saving watts.
How do I attach it?
Two low-profile M5 hex-headed bolts screw directly into the top tube mounting points; no straps are used. The 5 cm of fore-aft adjustment lets you align it precisely with the rear of your stem.
Does it work with steel, titanium or round-tube frames?
Yes. The Aero Top Tube Modules are optimised for modern, flat-surface carbon top tubes but are compatible with traditional round tubes; the slim profile and non-slip silicone base ensure a stable fit. Your frame needs top tube mounts for this bolt-on version.
Can I use it without the Aero Frame Module?
Yes. The module can be run on its own, or combined with the Aero Frame Module to create a complete watt-saving system with more carrying capacity.
About Apidura
Founded in 2013, Apidura designs bikepacking bags for long-distance and ultra-endurance riding, tested by riders on events such as the Transcontinental Race and the Tour Divide. The range is built around three families: the fully waterproof Expedition series for touring and all-weather bikepacking, the lightweight Racing series for ultra-distance racing, and the rugged Backcountry series for off-road trails.
Every Apidura product comes with a 3-year producer guarantee from the date of purchase, covering the entire product. After that, Apidura can support at-home repair or recommend a trusted repairer.
