Sacoche vélo cargo Surly Big Dummy Bag

The Surly Big Dummy Bag cargo bike bag is a side bag designed to maximize the load capacity of cargo bikes equipped with a "Dummy" rail system (Big Dummy, Big Easy, Big Fat Dummy). Designed for urban cyclists, travelers and families looking for a robust and modular solution, it focuses on durability, ease of use and practical cargo organization.

Positioned as a technical accessory for regular to expert users, the Big Dummy Bag emphasizes versatility: large storage for shopping and everyday use, the possibility of compression/explosion depending on the load and materials designed to last over time.

Features and Design

The Big Dummy Bag Version 2.0 embraces Surly's rugged, no-nonsense approach: a construction designed for the field, harsh weather, and intensive use. Its main shell is made of highly durable 1680D nylon, with an interior lining of 400D nylon, and all hardware (buckles, straps) is selected for its durability. The materials and hardware are bluesign® certified to reduce the environmental impact of production.

• Mounting System: Designed to attach to the dummy-style rails on Surly rear racks (optimal compatibility with Big Dummy, Big Easy, Big Fat Dummy). Straps and daisy chains allow the bag to be adjusted and secured to rails or similar supports.
• Construction and maintenance: 1680D fabric on the body, 400D liner, three stainless steel drains for easy rinsing and drying after use (compost, wet groceries, etc.).
• Modularity: Expandable cargo flap, side panels can remain flat or be tightened to reduce volume; external straps and buckles to carry additional loads.
• Organization: two internal pockets including a dedicated separation to keep documents and small items accessible and protected.
• Water resistance: sturdy design and protective lining - it's not a completely waterproof dry bag, but it stands up well to the elements and dries easily thanks to the drains.

Performance / Benefits

In use, the Big Dummy Bag stands out for its practicality and ease of integration: installation on rails is quick and secure, the adjustable straps limit swinging and help keep the center of gravity stable—essential on a loaded cargo ship. The expandable flap and adjustable panels offer a real plus for bulky shopping: you can compress it for minimal bulk or open it up to take on irregular loads.

On the road, the bag remains compact when lightly loaded and becomes a real trunk when you need to carry provisions, tools or light camping equipment. The robust materials reduce the risk of premature wear and facilitate maintenance: a simple rinse and dry are often sufficient. For cyclists looking for reliability and simplicity, it offers an excellent compromise between capacity, durability and modularity.

Technical specifications

• Model: Surly Big Dummy Bag — Version 2.0
• Capacity: approx. 22.5 L per bag
• Materials: 1680D nylon body, 400D nylon lining
• Certifications: bluesign® Approved fabric and hardware
• Attachment: compatible with “Dummy‑style” rails (Surly Big Dummy / Big Easy / Big Fat Dummy) — adjustable straps and daisy chains
• Flap: Expandable cargo flap for variable volume
• Internal storage: 2 interior pockets with divider
• Drainage: 3 stainless steel drain ports
• Hardware: Heavy-duty, adjustable buckles and straps
• Maintenance: rinsing and drying made easier by the drains
• Color: Black (generally offered)
• Estimated Weight: Heavy-duty construction—moderate weight appropriate for capacity (optimized for durability rather than extreme lightness)

Compatibility and “size” guide

The Big Dummy Bag is sold in pairs and its main compatibility criterion is the type of rear rail. Before purchasing:

• Make sure your rack is a "Dummy" type or has a compatible side rail. Surly designs these bags to fit naturally on the Big Dummy, Big Easy, and Big Fat Dummy models.
• Practical capacity: 22.5 L per bag — ideal for two shopping bags or for light travel storage.
• Between two mounting configurations, favor a low and tight position on the rail to minimize the impact on handling. If you are undecided between several mounting options, choose the option that keeps the bag closest to the rear hub to maintain stability.

Practical advice:

• For everyday city use, fill and compress the bag to limit swinging.
• For lightweight bikepacking or bulky shopping, use the maximum capacity of the expandable flap and secure loads with the external straps.
• After transporting dirty or wet items, rinse the bag and let it dry using the drain ports.

👉 What we like about this bag at BeastyBike is its durable construction, its smart interior organization and its modular capacity - a reliable accessory for cargo cyclists who want to carry more without complicating their lives.