Electrifying a “Douze Cycles”: French Biporteur and Longtail Bikes, A Complete Guide (2026)

• Douze Cycles cargo bikes (G4 two-door model, LT1 and LT2 longtails) are compatible with the PowerTrail Z8 48V kit.
• This French brand designs its bikes to last—the steel frame is a major advantage for electrification.
• A business customer uses an electric Douze Cycles G4 on a daily basis to transport cargo.
• Buying a used Douze Cycles and converting it to electric saves several thousand euros compared to a new electric cargo bike in a similar price range.

Introduction

Douze Cycles is one of the few French brands to have made a name for itself in the world of cargo bikes. Designed and assembled in France, these two-wheeled cargo bikes and longtails have carved out a niche for themselves alongside the Danish and Dutch manufacturers that dominate the market. The brand offers a complete lineup—from the G4 two-wheel cargo bike to the LT2 longtail, including the Traveller and the Messenger—all sharing a common philosophy: sturdy, practical, and durable cargo bikes designed for everyday use in the city.

But a Douze Cycles cargo bike—the pedal-powered version—loaded with professional equipment or two children requires considerable effort as soon as the terrain starts to slope upward. This naturally raises the question: Can a Douze Cycles bike be converted to electric? What kind of kit would be needed? And how does this option compare to buying a brand-new Douze Cycles electric cargo bike?

This guide covers everything you need to know—the different models in the lineup, the used market, technical compatibility, the recommended kit, and feedback from a business customer in France.

Douze Cycles: The French Cargo Bike Brand

Douze Cycles holds a unique position in the cargo bike market in France. It is one of the few brands to design and assemble its products in France—a key selling point for cyclists seeking traceability, quality, and local after-sales service.

The Complete Douze Cycles Lineup

The brand offers several types of cargo bikes, each designed to meet different needs:

The G4 is the flagship two-door cargo bike. With a steel frame, a modular front cargo platform, and a maximum load capacity of 200 kilograms, it’s the brand’s go-to cargo bike for both families and professionals. It comes in both a pedal-powered version and an electric version (G4e). The G4 is available in several customizable configurations—choosing the options that suit your needs is easy thanks to the configurator on the Douze Cycles website.

The LT1 and LT2 are the longtail models in the lineup. More compact than a two-door cargo bike, these cargo bikes with an extended rear section are practical for transporting children or cargo around town. The LT2, in particular, has been praised for its excellent balance between cargo capacity and maneuverability—a type of cargo bike that closely resembles a classic city bike.

The Traveller is a cargo bike designed for long distances and travel—a sort of adventurous longtail bike, ideal for cyclists who want to travel independently.

The Messenger is designed for couriers and delivery professionals—a fast and functional urban cargo bike.

The Ruff is a more compact model, ideal for those looking for a small cargo bike for city use.

All of these bikes have one thing in common: a high-quality steel frame designed to last for many years. It is this durability that makes Douze Cycles particularly attractive on the used market—and as candidates for electrification.

A steel frame: the key advantage

The choice of steel is no accident. This material offers superior fatigue resistance compared to aluminum, ideal vibration-damping properties for riding in the city on sometimes rough road surfaces, and exceptional durability. A well-maintained Douze Cycles cargo bike can be passed down from one owner to the next without losing any of its structural integrity. This is partly why these bikes command such high prices on the secondhand market.

Buying a Used Douze Cycles: The Market in France

The secondhand market is a great way to get started with Douze Cycles. These cargo bikes are built to last—a secondhand model in good condition is a smart purchase, especially if you plan to convert it to an e-bike later.

Where can I find a used Douze Cycles?

Listings can be found on Troc Vélo, Le Bon Coin, Facebook groups dedicated to cargo bikes, and refurbishment platforms such as Rutile.bike or Upway. In Paris and other major cities, stores specializing in cargo bikes sometimes offer display models or bikes returned from service. It’s a good idea to check these sites regularly—used Douze Cycles sell out quickly because the brand has a good reputation among both sellers and buyers.

What are the prices on the used market?

A used G4 Muscular typically sells for between €1,200 and €2,000. A used LT2 falls within a similar price range. Factory-built electric versions (G4e) are rarer and more expensive. The price varies depending on the model year, overall condition, and included accessories.

What to Check Before Buying

Inspect the steel frame—no cracks in the welds, no deep corrosion. Check the steering and headset play. Check the brakes, chain, and cassette—these wear-and-tear parts are easy to replace. For a bike you plan to convert to electric, check that the bottom bracket is BSA-standard and that there is no excessive play. Ask the seller about the remaining warranty—Douze Cycles offers a frame warranty that’s worth checking.

Can a Douze Cycles cargo bike be converted to electric?

Yes. Douze Cycles’ pedal-powered cargo bikes are excellent candidates for electrification—this applies to the G4 as well as the LT1 and LT2 longtails.

The bottom bracket is BSA-standard and is directly compatible with the PowerTrail Z8 kit without any modifications or adapters. This is true for the vast majority of models in the lineup.

The steel frame is an advantage for electrification. Steel absorbs vibrations better than aluminum, which reduces the stress transmitted to the kit over time. The steel threads on the housing also provide a more secure hold for the threadlocker—a practical detail that ensures the reliability of the installation.

There is enough space around the crankset. The geometry of Douze Cycles bikes provides ample space for the kit, cable routing, and battery mounting.

The factory-installed engine is also available. Douce Cycles offers the G4e, a factory-equipped electric version. Other models in the lineup have been offered with different powertrains over the years. Electrification using a third-party kit makes sense in several situations: if you already own a pedal-powered bike, if you’ve found a good deal, or if you’re looking for more torque than the original motor provides.

Which kit should I choose for a Douze Cycles cargo bike?

The recommended kit is the PowerTrail Z8 48V.

Douze Cycles cargo bikes—whether the G4 two-wheeled cargo bike or the longtails—are designed to carry heavy loads. The PowerTrail Z8’s 120 Nm of torque is perfectly suited for this type of bike: pulling away uphill with a full load, accelerating through city traffic, and smooth riding on daily commutes.

The built-in torque sensor is essential on a loaded cargo bike. It adjusts the assistance proportionally to the pressure on the pedals—for a smooth, controlled start without any jolts. This feature is what sets a high-quality kit apart from a basic product with a Bafang BBS-style rotation sensor.

Recommended battery: Hailong 720 Wh for professionals and routes with elevation changes. The Wedge 480 Wh is a good option for short, flat urban trips.

Complete configuration:

• Kit: PowerTrail Z8 (TSDZ8, 120 Nm, torque sensor)
• Battery: Hailong 720 Wh (48V)
• Display: SW102 (IP65 waterproof)
• App: SykloConnect
• Firmware: Open Source (OSF) — customize assistance profiles based on the type of ride

Installation on a Douze Cycles

Installation follows the standard PowerTrail Z8 procedure, with no major complications. A motivated DIYer can easily install it on a Douze Cycles cargo bike—the simple steel frame and standard BSA bottom bracket make each step straightforward.

Removing the original crankset. Remove the cranks, then unscrew the BSA bottom bracket shell. On a Douze Cycles bike, the steel threads come out cleanly.

Assembling the kit. Insert the TSDZ8, apply threadlocker, tighten, and install the cranks provided. This part of the process takes only a few minutes.

Securing the battery. The Hailong attaches to the down tube. On the G4, it can also be mounted in the front triangle—which lowers the center of gravity and frees up space on the frame. Choose the configuration that best suits your riding style.

Wiring. The wiring runs along the frame to the SW102 display mounted on the handlebars. On a two-speed bike, routing the wiring along the head tube requires a bit of care to achieve a clean look.

Estimated installation time: 2 to 4 hours. A workshop in the Syklo network can also handle the entire installation—send an email to the team to get the address of the nearest partner workshop. From Paris, there are several workshops available in the Île-de-France region.

User Review: An Electrified Douze Cycles G4 for Professional Use

This customer uses his Douze Cycles cargo bike every day in a demanding professional setting. The bike carries equipment and heavy loads on regular trips around town—a type of use where reliability is non-negotiable. A bike that’s out of commission means a lost workday.

The PowerTrail Z8 48V kit with a 720 Wh Hailong battery meets this requirement. The 120 Nm of torque makes it easy to move the loaded cargo bike, even when starting on a hill or after a long stop. The assistance is smooth and predictable—exactly what a professional needs to complete their routes with confidence.

The kit’s reliability over time is one of its most appreciated features. The open-source firmware allows you to customize the assistance level based on the day’s load—a handy feature when loads vary from day to day. The SW102 display shows real-time power consumption, which helps you plan how many kilometers you have left for the entire day.

“Responsive team, careful shipping. Well-made equipment!! I’m satisfied with how it was installed on a new cargo ship. Perfect!” ” – Stephan

Douze Cycles Syklo E-Bike vs. Douze Cycles Factory Electric Cargo Bike

Douce Cycles offers the G4e, a factory-equipped electric model. Here’s how this option compares to a conventional bike converted to electric power using the Syklo kit.

The couple. The G4e’s standard motor varies by model and model year. The PowerTrail Z8 delivers 120 Nm—more torque than most motors found in cargo e-bikes in this class. You can feel the difference right away when climbing hills and pulling away with a heavy load.

The price. A new G4e falls into the higher price range. A used, high-performance G4 (€1,200 to €2,000) converted to electric power with the PowerTrail Z8 kit comes to a total cost of approximately €2,700 to €3,500. The savings are considerable, and the final product often delivers more torque than a factory-built electric cargo bike.

Integration. The factory-standard G4e features internal wiring and a seamless design. The Syklo kit is visible—but neat and functional. For some professionals, the kit’s discreet appearance is actually an advantage: the bike doesn’t look like an electric bike, making it less attractive to thieves.

Reversibility. The kit can be disassembled and transferred to another cargo bike—a level of versatility that’s impossible with a factory-installed motor.

Customization. The open-source firmware allows you to create custom assistance profiles. You can switch between eco mode for light rides and power mode for heavy loads in just a few seconds on the display.

The warranty. Douze Cycles offers a warranty on the frames of its bikes. Adding a third-party kit should not affect the structural warranty—but it is recommended that you check the terms and conditions with the manufacturer. The Syklo kit is covered by a 24-month warranty.

Budget for Electrifying a Douze Cycles

Electrify a bike you already own: PowerTrail Z8 48V kit + battery: starting at €1,200, up to €1,800. Shop installation: €50 to €150.

Buy a used Douze Cycles and convert it to electric: used G4 (€1,200 to €2,000) + kit (~€1,500): total budget of €2,700 to €3,500. This offers the best value for money when it comes to getting a high-quality French electric cargo bike. Used LT2 + kit: similar price range.

Comparison with buying a new electric cargo bike: A new G4e is significantly more expensive. The price difference runs into the thousands of euros—a savings that makes it worth taking the time to look for a good used bike and convert it to electric.

Financial Assistance: Some regions and metropolitan areas in France offer financial assistance for the purchase of conversion kits. Check your local government’s website.

Douze Cycles Specific FAQ

Is the kit compatible with all models in the line? The PowerTrail Z8 is compatible with the main Douze Cycles cargo bikes in their pedal-powered versions: G4, LT1, and LT2. For specific models (Traveller, Messenger, Ruff), a case-by-case check is recommended—simply send a photo of the bottom bracket to the Syklo team.

Is the kit compatible with the G4e (factory-standard electric version)? Replacing the original motor with a Syklo kit is technically possible. This is a viable option if the factory motor fails after the warranty has expired, or if you are looking for higher torque. Contact Syklo for a case-by-case evaluation.

Can we choose between the G4 and the LT2 for electrification? Both types of bikes are compatible. The G4 (two-wheel carrier) is designed for transporting bulky loads in the front—such as work equipment or children in a cargo box. The LT2 (longtail) is more compact and easier to maneuver in the city, with the cargo carried in the rear. Choose the model that best suits your daily needs.

Why choose the Douze Cycles over another cargo bike? Three main reasons. The brand is French—design, assembly, and after-sales service are all handled in France, through Paris and the dealer network. The steel frame is a durable product that can be passed down and resells well on the used market. And the lineup is extensive—from cargo bikes to longtails, including delivery and touring models, there’s a Douze Cycles bike for every need.

Where can I buy a Douze Cycles in France? Bikes are available at the brand’s retailers in France. In Paris, several stores offer test rides and delivery. Visit the Douze Cycles website to view the list of partner retailers. For used bikes, websites like Troc Vélo and Le Bon Coin, as well as refurbishment platforms, regularly post listings. We recommend checking these sites frequently—good deals go fast in this type of market.

What is the range of an electric Douze Cycles? With the Hailong 720 Wh, you can expect a range of between 50 and 80 kilometers under real-world, fully loaded conditions. This is suitable for the vast majority of daily commutes in the city and suburbs. Professionals who make long rounds can take advantage of the high-capacity battery to get through a full day without recharging.

Does the kit make permanent changes to the bike? No. The kit is reversible—it can be removed to restore the bike to its original pedal-powered cargo bike configuration, or transferred to another bike. No permanent modifications to the frame are required. That’s part of the appeal of this solution compared to a factory-installed motor.