Brompton has launched its lightest ever bike, the T Line, which it claims is "a new benchmark for folding bikes in lightness, ride performance and robustness”
Weighing just 7.45kg and built around a precision engineered titanium frame, the British brand is hailing the T Line as a reinvention rather than a mere redesign of its iconic folding bike design. Previously its lightest offering was the P Line, which was released in November 2021 and weighs 9.65kg.
“The only thing that has been carried over from our classic model is the brake system. Everything else has been finessed, pared back, upgraded,” says Will Carleysmith, chief design and engineering officer at Brompton. “We have gone over this entire product in the minutest detail, looking for every single gram we can find to save on weight”.
To achieve this Brompton opened a dedicated factory in Sheffield, where the titanium frames are built, using orbital and tig-welding for improved strength. The frames are then sent to its London factory, where they are fitted with over 150 redesigned components.
Certainly Brompton could never be accused of doing things by half. But it saw the creation of a dedicated factory a necessity, largely due to the nuances of building bikes in titanium.
“Working with titanium takes a high level of knowledge, experience and diligence, so finding the right partner who shared our vision and belief in what could be achieved with titanium was critical,” says Paul Williams, Brompton’s chief operations officer.
“Our relationship with C W Fletcher, based in Sheffield, started over seven years ago. With them we built Brompton Fletcher, a dedicated company with a purpose-built production facility and skilled team able to work with this demanding material and fabricate these fantastic titanium frames.”
When setting out to design its lightest bike ever, titanium was the obvious choice. “It has the highest strength-to-density ratio of any metallic element, along with great impact strength and corrosion resistance,” says Williams, “making it the perfect material to create the ultimate lightweight folding bike, able to withstand the punishing impacts of the city”.
Brompton says the T Line is 37% lighter than the classic all-steel equivalent but just as strong, good for a load of up to 110kg. It also believes that the bike will be more compliant, thanks to titanium’s shock-absorbing properties.
But the frame isn’t the only reason that it's been able to produce a folding bike built for the city that weighs the same as many high-end carbon road bikes.
The T Line also features an injection of carbon, most notably in the shape of a pioneering new seat post. Brompton says it's the first bike in the world to be fitted with a steel-armoured carbon post. To withstands the rigours that a folding bike experiences daily, its engineers created a new process which reinforces the carbon with 0.3mm steel armour.
There’s also a one-piece carbon fork and carbon handlebars that are wider than those on previous Bromptons, designed to make the bike “stiffer and even more responsive”.
The crankset is carbon too, part of a brand new patent-pending drivetrain, which Brompton has designed to sit inside the bike's fold.
The T-Line will be offered in two specifications, the single-speed T Line One, which is its lightest iteration, and the T Line Urban, which features a compact four-speed gearing system and mudguards.
According to Brompton the rear mech on the Urban weighs just 60g, while the gear ratio has also had an overhaul, apparently tested from “Amsterdam to San Francisco”. Which should mean that its range is as appropriate for the hills as it is flatter roads.
The lure of the T Line will undoubtedly be its reduced weight and notably how that affects its portability. With this in mind Brompton has sought to improve the bike’s folding attributes, so it’s not just lighter to carry but faster to fold too. This means new self-aligning hinges, a spring-loaded handlebar catch and what Brompton describes as “an easy-grab carbon saddle”, which features an integrated nose handle.
“What we’ve ended up with is the sense that when you leave the house you can go anywhere,” says Carleysmith. “All of those shared environments you experience when exploring a city, the T Line is not going to be a burden, and you can do whatever you want with ease".
The Brompton T Line is exclusively available via an online ballot system as well as through selected Brompton Junction stores in London, New York, Shanghai, Singapore and Paris.
The T Line One has an RRP of £3,750/$4,795/€4,360 , while the T Line Urban will cost £3,950/$4,995/€4,590.
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