Concept → Reality · Rewritten

The bicycle that wanted to be a backpack

In 2008, a Taiwanese designer drew a bicycle that folded into a backpack and was meant to weigh 5.5 kg. It never went on sale, but the problem it tackled, the last mile after the train, shaped the folding bikes that did.

The Design Blog editors

A black Brompton folding bicycle, fully folded

A folded Brompton, the reference commuter folder: compact enough to carry, not to wear. AI-retouched from an image by Guy Chapman, Public domain.

Verdict 2026

Still a concept

The Backpack Bicycle never went into production; it remained a 2008 competition concept by Chang Ting Jen. Its core promise, a bike small enough to carry like luggage, arrived in other forms, from Brompton’s titanium T Line to the carry-on-sized Kwiggle.

Brompton C Line 2-SpeedClosest thing you can buyBrompton C Line 2-Speed8.9Design ratingTri-fold steel frame, stiff and quickCheck priceOur design review ↓

The idea today

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No bike fits in a backpack yet, but these designs get the ride, the helmet and the lock close to it.

  • Brompton C Line 2-Speed

    Brompton C Line 2-Speed

    The reference folding commuter bike: a steel frame that folds into a compact package in seconds and rolls on its own wheels.

    Our design review

    8.9Design rating
    Form9.0
    Material8.6
    Detail8.6
    Longevity9.2

    The C Line keeps Brompton’s 1975 tri-fold: a hand-brazed steel frame that folds into a small package in under 20 seconds, with an elastomer block that works as rear suspension and also serves as a fold pivot. Reviewers at Cyclist praised its build quality, a frame that stays decently stiff at the hinges, and the punchy in-house brakes. The 2-speed setup keeps it light and simple but suits flat cities best. The composite hinge-clamp levers feel less special than the rest of the bike.

    Strongest point
    Tri-fold steel frame, stiff and quick
    Compromise
    Two gears limit it to flatter routes
    Check price on Amazon
  • Closca Foldable Helmet

    Closca Foldable Helmet

    A certified bike helmet that collapses flat enough to slip into a bag once you are off the bike.

    Our design review

    7.9Design rating
    Form8.6
    Material7.8
    Detail7.6
    Longevity7.4

    Closca’s helmet uses telescoping rings of polycarbonate-shelled EPS that press down into one another, so a round city helmet becomes a disc about 6.5 cm tall. It only collapses when nothing is inside it, and the vents hide in the grooves of the fold, which keeps the shell smooth and calm. Fit comes from an elastic rear band set once, not a dial, with washable pads. Discerning Cyclist’s reviewer found the folding excellent but the interior less comfortable than sportier helmets.

    Strongest point
    Folds flat in a second, smooth shell
    Compromise
    Elastic band fit instead of an adjustment dial
    Check price on Amazon
  • Seatylock FoldyLock Compact

    Seatylock FoldyLock Compact

    A folding link lock that packs into a short, flat block instead of a loose chain.

    Our design review

    8.1Design rating
    Form8.4
    Material8.0
    Detail8.3
    Longevity7.8

    Steel-cored plates joined by rivets fold like a carpenter’s rule into a block just under 19 by 6 by 4 cm, and the lock barrel is built into the end plate instead of hanging off a chain. A plastic coating on every plate protects the paint, and the frame bracket bolts to the bottle bosses. Reviewers at BikeRadar found it rattle-free on the bike but noted the links went slightly stiff after heavy rain. The flat plates are also thinner than a D-lock shackle.

    Strongest point
    Folds flat like a carpenter’s rule
    Compromise
    Plates thinner than a D-lock shackle
    Check price on Amazon

Product images from the retailer listings, cut out and staged with AI.

  1. 1976Andrew Ritchie founds Brompton in London, the company behind the folding bike most commuters still compare against.
  2. 2008Chang Ting Jen’s Backpack Bicycle, an entry in the International Bicycle Design Competition, appears on design blogs with a 60 cm folded length and a 5.5 kg target weight.
  3. 2016Kwiggle launches a Kickstarter for a bike that folds to 55 x 40 x 25 cm, roughly airline carry-on size.
  4. 2022Brompton introduces the titanium T Line at a claimed 7.45 kg, its lightest bike to date.

What it was

In July 2008, a render from Taiwan made the rounds of design blogs. Chang Ting Jen called it the Backpack Bicycle, and it was his entry in the International Bicycle Design Competition. The pitch was simple: ride to the station, fold the bike, and carry it on your back.

Folded, the bike was meant to measure about 60 cm and weigh 5.5 kg. To get there, Chang proposed a plastic main frame. The package also doubled as a handcart, so it could be rolled rather than carried.

The idea addressed a real gap. Public transit gets you between districts, but rarely to the door. A bike that rides the train with you closes that last stretch, and it needs no parking spot and no rack at either end of the journey.

A bike can be small, light or comfortable. Real products pick two.

Why it stayed a drawing

The numbers were the problem. Even in 2008, critics doubted that a plastic frame could carry an adult rider safely, and nothing showed that 5.5 kg was reachable with hinges, wheels and a load-bearing frame. We found no record of a working prototype or of a maker taking the design on.

A bike that folds into a backpack also has to accept small wheels, short handlebars and a compromised riding position. Every gain in packability costs something on the road. The render did not have to settle those trade-offs. A real product does.

Where the idea went

The goal survived, even if the backpack did not. Brompton, founded by Andrew Ritchie in 1976, still sets the reference for a commuter folder, and it now builds around 50,000 bikes a year. In 2022 it introduced the titanium T Line at a claimed 7.45 kg, the lightest bike it has made. It is light enough to carry up stairs, not light enough to wear.

The closest real heir is the Kwiggle. It went to Kickstarter in December 2016 as a bike that folds to 55 x 40 x 25 cm, about the size of airline carry-on luggage. The price of that size is posture: the rider stands almost upright with a small seat for support.

Eighteen years on, the honest answer is that a bike can be made small, or light, or comfortable, and real products pick two. The Backpack Bicycle promised all three, which is why it remains a drawing worth remembering rather than a bike you can buy.

The original post, summarized

Our 2008 post introduced Chang Ting Jen’s Backpack Bicycle, a competition entry that folded into a 60 cm backpack, weighed a proposed 5.5 kg and doubled as a handcart. It is summarized here rather than republished.

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