New Brompton G Line ramps up this legendary folding bike’s go-anywhere abilities

Cultish bike builder Brompton has overhauled its classic design, with bigger wheels and a stronger frame to create a folding bike that can go anywhere, whether open or closed. ‘Brompton started with Andrew Richie’s really singular focus,’ says Will Carleysmith, the company’s chief design and engineering officer. ‘He talked of the bike as a “magic carpet device”, something you could use to fly around the city and roll up when you’re not using it,’ Carleysmith continues. ‘People fell in love with this little device – it was built for unlocking the city.’

Since the Brompton debuted in 1975, it has become more than just a cult object, but an essential piece of city transportation. Current production is 100,000 bikes, 70 per cent of which are exported from the UK. Over the years, the use case for Bromptons has grown along with their popularity. ‘It is very tough, surprisingly so for its super compact size,’ Carleysmith notes. ‘However, the original bike was never intended to go off road. So we had a new use case for old fans and new ones. A bike that could do more.’

The first 20-inch-wheel version of Brompton’s patented folding design required a huge amount of work. ‘Originally, we wanted to explore how far the Brompton three-part fold system could be pushed while still keeping the brand’s DNA,’ Carleysmith explains. ‘We have a very substantial test lab full of bespoke equipment. One of the nice things about making the same thing for a very long time is that you understand it very well indeed.’

The development process saw a number of prototypes constructed. Each mule evolved through tiny but perceptible changes to the frame and set-up to give the 20-inch bike a different set of characteristics than its 16-inch-wheeled siblings, the T Line and the standard Brompton. ‘The new bike had to feel different and have a reason to exist, rather than just feel like the current bike,’ says Carleysmith. ‘Bromptons are very agile and quick-steering. We wanted to add a lot of stability, but initially we went too far and lost some of the Brompton character.’

One of the key knock-on effects of the bigger wheels was a change in the size of the frame, with scope for fatter tyres as well. ‘Tyre technology has moved on a lot in ten years – this product really leans into that,’ says Carleysmith. As a result, the G Line comes with custom-made Schwalbe tyres, along with hydraulic disc brakes and a Shimano 8-gear hub system. ‘As the bike gets bigger, the grip gets better,’ Carleysmith says. ‘The main part of the frame is steel as before, but the front part is formed aluminium, which is new to us.’

‘More engineering went into the e-system than anything else. Normally in our industry you get an electric system off the shelf. None of these worked for us, so we’ve invested a lot into creating our own,' Carleysmith continues. The Electric G Line therefore has an all-new 250-watt rear hub motor offering three levels of assisted riding. It’s powered by a 345-kwh battery, offering between 20 and 40 miles of range in one go. ‘Because you lift the bike, we aim to ensure the battery can be separated very quickly – it’s just a single button to separate the bulk of the weight,’ he explains.

The battery can be carried in its own bag and therefore easily charged wherever you happen to be. With battery, the Electric G Line weighs 19.5 kg (a hefty penalty over the company’s current lightest model, the sub-8kg but non-electrified T Line).

‘One of the interesting things about designing for Brompton is that the bike comes with you – in your house, on the train, by your desk. A lot of the work we do goes into making it rollable – like a suitcase. For example, these days you don’t really carry your luggage, you roll it,’ Carleyfield says. When folded, the smallest G Line model measures 690mm by 730mm by 402mm, a mighty amount of transport power in a tiny package. It’s no match for a regular mountain bike, of course, but the 20-inch wheels make light work of shortcuts and uneven surfaces.

‘The G Line truly is one bike to do it all. Brompton owners are passionate about their bikes but it has always been a bike optimised for cities,’ says the company’s CEO, Will Butler-Adams. ‘Now, as more and more people look to escape the city, exploring roads and trails less travelled, it was the right time to take everything that makes the Brompton so special, and make it capable of going beyond the urban environment and into tougher terrain.’

Recent collaborations include a custom-framed C Line by artist Shantell Martin, partnerships with menswear designer Oliver Spencer and streetwear brand Palace, as well as the unlikely sight of two C Lines given a glamorous gold-plated treatment by a team of craftspeople from Mappin & Webb. Andrew Richie’s vision was prescient, and the new Brompton G Line will keep his creation very much at the forefront of personal transportation.

The Brompton G Line starts at £2,395 for the 8-Speed model, going up to £3,495 for the 4-Speed Electric G Line; extras include a luggage rack, mudguards, bespoke bags and water bottles, and an in-frame toolkit. All models are available in Forest Green, Adventure Orange or Traildust White, Brompton.com, @BromptonBicycle