Brompton’s new G Line is its first off-road bike – but don’t call it a gravel bike

‘World’s most versatile bike’ sports 20in wheels and disc brakes

By Stan Portus

Published: Tuesday, 17 September 2024 at 09:00 AM

The new Brompton G Line looks similar to the brand’s other models, with its arching top tube, small wheels and two hinges to fold it away.

But, on closer inspection, this new folding bike is markedly different.

Instead of 16in wheels with slick city tyres, it has 20in wheels wrapped in wide, 54mm rubber. It doesn’t have rim brakes; there are disc brakes instead. The geometry has been tweaked, and there’s an aluminium fork and an 8-speed gear hub from Shimano.

The bike is billed as “Brompton’s biggest launch in 50 years”, with the London-based company having stuck to its smaller-wheeled, urban folding bikes since it was founded in 1975.

Brompton claims the G Line – available as a non-assisted or electric bike and from £2,395 / €2,849 – is the “most versatile bike in the world”. CEO Will Butler-Adams says it’s a response to the growing interest in off-road riding and people looking to explore “roads and trails less travelled”.

But if it’s beginning to seem as though the ‘G’ in its name might stand for gravel, think again. Brompton doesn’t want you to think of its new folding bike quite like that.

Eight years in the making

The G Line had its genesis in how people pushed their Bromptons in extreme environments. – Brompton

Brompton’s head of design, Will Carleysmith, says the idea for an off-road Brompton stretches back roughly eight years.

“The idea came from what people were doing with the Brompton,” says Carleysmith.

“We had people taking it into environments it wasn’t perhaps designed for. We had guys at the North Pole cycling to their instruments across the ice and people travelling around Southeast Asia. And then you get people doing like Paris–Brest–Paris and [Land’s End to] John O’ Groats.”

Carleysmith says the early prototypes for the G Line resembled something from the TV show Scrapheap Challenge, where teams of mechanics and engineers would build machines to complete specific tasks from whatever was lying around in a scrapyard.

Since then, Brompton has launched three bikes. It also had to navigate the cycling industry’s coronavirus boom and the ensuing downturn. This meant the G Line remained on the back burner.

“It’s been a long-term thing that’s been in the background and it’s probably been four years’ work to get it to a mass-produced product,” says Carleysmith.

Don’t call it a gravel bike

Brompton G Line being ridden along gravel trail. — Brompton wants the G Line to be seen as a “versatile bike that can do pretty much everything“. – Brompton

Straddling on- and off-road riding and launched with the gravel-ism of roads and trails “less travelled”, the G Line shares a similar ethos to the best gravel bikes.

Throw in the fact it uses Schwalbe G-One tyres – gravel tyres, no less – along with the suggestive ‘G’ in its name, and it’d be fair to assume that this is indeed a folding gravel bike. However, Brompton doesn’t want to categorise the G Line this way.

Carleysmith points out that riders in other countries may interpret the ‘G’ differently. For example, it could stand for gëlande in German, which roughly translates as terrain or ground, and is arguably closer to Brompton’s framing of the G Line as an ‘all-terrain’ bike.

“We would love this bike to be seen as just a very versatile bike that can do pretty much everything.

“It’s not a performance bike or a mountain bike, but it’ll do the job and it won’t cause you grief,” says Carleysmith.

A new audience

Brompton G Line folded up by mountain lake. — The new Brompton is aimed at the ‘mainstream bike market’. – Brompton

Carleysmith says there are people who “just absolutely love Bromptons”, with more than a third of Brompton’s customers owning more than one of its bikes.

But he says the G Line is aimed at those “who would reject the Brompton or a compact folding bike because of what they see as its perceived capability”.

“We really want to sell to the compact bike, hybrid bike [market and] perhaps some of the people who buy gravel bikes,” says Carleysmith.

Reaching a new audience can be read as combining Brompton’s financial and philosophical aims. Brompton’s planned move to a new factory in Ashford, Kent, will double production capacity to approximately 200,000 bikes a year.

Selling more bikes to more people also reflects Butler-Adams’ belief in Bromptons, as shared in his book The Brompton: Engineering for Change. Butler-Adams says hardly any Brompton owners he’s met have said anything other than its bikes have changed their lives, saying they’re happier and healthier for riding one of these folding bikes.

“Based on everything I’ve seen, there’s no way we could be content in leaving Brompton as a niche, cult product with a small fan base of enthusiasts,” he writes, later explaining the role cycling – and specifically Bromptons – can play in tackling climate change and making cities more livable.

The sales pitch is the G Line rides like conventional bikes but comes with the Brompton’s convenience.

Compared to a conventional bike, Carleysmith says that with a Brompton G Line, “If you go away for the weekend you don’t have to drag your kind of roof rack out and set it up on the car.”

Brompton’s head of design adds that you can still fold the bike up and head home on the train if you’re faced with bad weather, “which is rather lovely.”

Brompton would still steer urban riders towards its classic bikes rather than the G Line.

“We’re really after the ‘mainstream bike market’, but with added Brompton usability and magic,” says Carleysmith.

Disc brakes and no hands

Man riding Brompton G Line around corner. — This is the first Brompton to use disc brakes. – Brompton

The appeal to the mainstream can be seen in how the G Line uses tech that’s now common across the cycling market and has less compromising ride characteristics.

Disc brakes bring Brompton’s latest folding bike into the modern age and help increase the bike’s versatility through different weather and terrain. Instead of developing the brakes in-house – as it did with its rim brakes – Brompton uses TRP levers and calipers on the G Line.

Brompton says the Shimano Alfine 8-speed internal gear hub, operated via a Microshift shifter, helps you cover a variety of terrain, while being low-maintenance.

Along with the larger 20in wheels and 54mm tyres, these features provide “game-changing comfort and capability”.

Brompton has also revised the G Line’s geometry to further the bike’s off-road aims, employing the help of an unnamed but “world-leading bike fitter”.

Compared to Brompton’s classic bikes, the G Line has a longer wheelbase and can be ridden with no hands. This might seem like a minor detail, but it speaks to how Brompton has worked to improve the stability of the bike over its other models.

Larger wheels and a longer wheelbase mean the G Line is less compact than other Bromptons, measuring 690x730x402mm when folded.

The G Line also differs from Brompton’s classic bikes because it uses an aluminium rather than steel fork.

The fork and stem are dotted in mounts for any bags or bottle cages, furthering the bike’s versatility.

Brompton has fitted the bike with a wide handlebar for stability, leverage and comfort on longer rides.

Electric, too

Man pushing Brompton G Line folding bike along concourse. — Brompton says the G Line Electric sets “the benchmark for quality and safety”. – Brompton

The G Line will be available as an electric folding bike. Whereas the Brompton P Line Electric has a front hub motor, the G Line Electric uses a 250W rear hub motor, which is beneficial for off-road riding.

“When you’re riding on loose surfaces, there’s a lot of weight on the back of the bike. So for us that made more sense than a front hub motor which you know on a city bike works well,” says Carleysmith.

It’s not just the position of the motor that’s changed. Brompton has developed an entirely new electronic system for the G Line Electric.

“With the new system, we have pretty much put all of the electronics and software technology into one controller, which means we can be a lot more flexible with the system,” says Carleysmith.

“It also allows us to have a lot more connectivity, so we can have what we call over-the-air updates which are becoming increasingly common,” he adds, comparing the connectivity to how you would update your smartwatch or bike computer via your phone.

Brompton says its latest ebike battery delivers 345kWh of power for a 30-60kph range per charge via a more efficient system.

The G Line Electric is also said to set “the benchmark for quality and safety”, with the folding bike brand actively supporting greater regulation through the Battery Breakdown Safety Bill, which is intended to address battery fires.

Compared to the non-assisted G Line, this electric folding bike has four speeds and comes with integrated bike lights.