The new Brompton G Line looks similar to the brands 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 doesnt have rim brakes; there are disc brakes instead. The geometry has been tweaked, and theres an aluminium fork and an 8-speed gear hub from Shimano.The bike is billed as Bromptons 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 its beginning to seem as though the G in its name might stand for gravel, think again. Brompton doesnt want you to think of its new folding bike quite like that.Eight years in the makingThe G Line had its genesis in how people pushed their Bromptons in extreme environments. - Brompton Bromptons 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 ParisBrestParis and [Lands 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 industrys coronavirus boom and the ensuing downturn. This meant the G Line remained on the back burner.It's been a long-term thing thats been in the background and its probably been four years' work to get it to a mass-produced product, says Carleysmith.Dont call it a gravel bikeBrompton 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 itd be fair to assume that this is indeed a folding gravel bike. However, Brompton doesnt 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 glande in German, which roughly translates as terrain or ground, and is arguably closer to Bromptons 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.Its 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 audienceThe 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 Bromptons 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 Bromptons financial and philosophical aims. Bromptons 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 hes met have said anything other than its bikes have changed their lives, saying theyre happier and healthier for riding one of these folding bikes.Based on everything Ive seen, theres 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 Bromptons 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.Bromptons 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 handsThis is the first Brompton to use disc brakes. - Brompton The appeal to the mainstream can be seen in how the G Line uses tech thats now common across the cycling market and has less compromising ride characteristics.Disc brakes bring Bromptons latest folding bike into the modern age and help increase the bikes 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 Lines geometry to further the bikes off-road aims, employing the help of an unnamed but world-leading bike fitter.Compared to Bromptons 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 Bromptons 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 bikes versatility.Brompton has fitted the bike with a wide handlebar for stability, leverage and comfort on longer rides.Electric, tooBrompton 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.Its not just the position of the motor thats 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.Brompton G Line models, prices and availabilityThe bike will be available in five models and three colours. - Brompton The Brompton G Line will be available from Monday 7 October.There will be a G Line Electric model and four non-assisted models, each with a combination of accessories.The folding bike will be available in three colours: Forest Green, Adventure Orange or Traildust White.All models will be available in three sizes, which you select based on your height:Small: 152-168cm (5ft-5ft 6in)Medium: 168-183cm (5ft 6in-6ft)Large: 183198cm (6ft-6ft 6in)Brompton G LineThe Brompton G Line starts at just under 2,400. - Brompton Price: 2,395 / 2,849Weight: From 13.9kgBrompton G Line with rack and mudguardsThe rack has four small wheels for easy manoeuvring when folded. - Brompton Price: 2,495 / 2,969Weight: From 14.8kgBrompton G Line with lightsYou can get the entry-level G Line with added lights. - Brompton Price: 2,480 / 2,959Weight: Not specifiedBrompton G Line with lights and rackThe Brompton G Line in Adventure Orange with a rack, mudguards and lights. - Brompton Price: 2,580 / 3,079Weight: Not specifiedBrompton G Line ElectricThe Brompton G Line Electric has integrated lights. - Brompton Price: 3,495 / 3,999Weight: From 16.1kg without battery / 19.5kg with battery