Brompton T Line: how Brompton reinvented its folding bike in titanium

Only the brakes remain from the old Brompton and the weight is down to just 7.45kg

Brompton T Line
(Image credit: Brompton)

Imagine a folding bike that weighs just 7.45kg, that you can scoop up with one hand, and balance on a finger. Now meet the Brompton T Line. Using titanium instead of its standard steel, Brompton has gone away and redesigned practically every element of its iconic urban folding bike. Except, of course, the central hinged design. Brompton is adamant it found the perfect folding mechanism almost from the very first prototype of its first ever bike, so don't expect that to change any time soon. And given the success of its bike, why would it change? 

It seems like only last month that I was saying the Brompton P Line was the lightest Brompton ever – and at the time it was. However, with the T Line, Brompton has really gone and made over its iconic folding bike. The difference, as far as I can see, is that the P Line was a fairly standard Brompton with some titanium and new design elements. The T Line, by contrast, is a ground-up reinvention. In fact, Brompton says the only thing that has been carried over from its previous bikes is the brakes. The product of three years of research and development, it required new construction techniques, the design of over 150 components in titanium and the building of a new factory dedicated to making the titanium parts in, aptly, Sheffield.

I was given a sneak peak at the T Line, albeit only by watching someone else actually ride it, at a video launch event. Brompton is sending me one to review shortly, and hopefully I can avoid getting it stuck in a storm drain grate, which is what happened the last time I rode a Brompton. You can read about that – and a lot more in our Q&A with Brompton's head of design.

Now, if you get over-excited by looking at folding bikes, be warned: the following photos of this titanium dream machine are purest Brompton porn.

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Brompton T Line

(Image credit: Brompton)
Image 1 of 7

Brompton T Line

(Image credit: Brompton)

The main challenge with building the T Line was returning stiffness to the frame that was lost when moving to titanium. To give you an idea of how successful the engineering was, the new bike in its lightest form is 7.45kg. The P Line, which was the lightest Brompton, is 9.65kg… and the 'standard' C Line is 2 kilos heavier than that.

At the launch, riders were picking up the T Line and balancing it on one finger, and the ride of it looked nippier than ever. Bromptons are always faster and more fun to ride than they look like they should be, but the T Line seems to take that up a further notch. It will be interesting to see how much flex there is in the frame, and how it differs from standard steel Bromptons.

Just to be clear here, there are two versions of the T Line, and the headline 7.45kg weight refers to the single-speed T Line One. Also available, and I think likely to be somewhat more popular, is the T Line Urban. This adds 4 gears – using a tiny derailleur that weighs just 60g – and mudguards. As a result it's heavier than the purist T Line One, but not by much: it’s 7.95kg. Both models, Brompton says, 'can be comfortably ridden by a 110kg rugby player,' which probably tells you something about their target market.

Brompton T Line

The T Line's titanium elements are forged and welded in Sheffield, Steel City

(Image credit: Brompton)

What makes the titanium T Line tick?

New drivetrain

The 'entirely new, patent-pending drivetrain' is designed to sit inside the fold, even on the geared version. Clever design was required to ensure that the T Line Urban could be folded regardless of what gear it is in. The gear ratios were tested in Amsterdam (flat) and San Francisco (madly hilly) and 'perfected for city roads.'  

Allied to this is a new carbon crankset that Brompton says gives greater power transfer. 

New seat post

This is the sort of thing bike nuts love. Brompton found that 'can't stand up to the daily use of a folding bike.' So they reinforced the carbon with 0.3mm steel armour plate to produce a super-light seat post that can stand up to being folded, rained on and ridden by a 110kg rugby player. Standard.

New folding mechanism

Well, not new new. It's still the same mechanism at its core, but there are new, self-aligning hinges, a spring-loaded handlebar catch 'that effortlessly clicks' and the carbon saddle also has a new handle built into it. The result is a bike that is faster to fold than ever – not that previous Bromptons were exactly slovenly in this department.

Brompton T Line folding gif

Now that's a crisp action

(Image credit: Brompton)

The little wheels that sit at the back and let you roll the bike along when folded are also of a larger diameter, which should make it easier to navigate on crappier surfaces.

New ride feel

Brompton has plumped up the dynamics of the T Line, with carbon cranks and a cast titanium bottom bracket, 'for a faster ride.' Titanium's natural shock-absorbing properties should also make for a smoother ride, which is excellent news, given the current parlous state of the UK's roads. The one-piece carbon fork and wider carbon handlebars, meanwhile, 'make it stiffer and even more responsive.' Well, it should be fun anyway.

Brompton T Line: price and availability

Brompton T Line

T Line One front/right, T Line Urban rear/left

(Image credit: Brompton)

There are several more affordable Brompton models these days… but the Brompton T Line is not one of them, alas. Nor will it be straightforward to buy, at least at launch. 

• T Line One (single speed, no mudguards, 7.45kg) £3,750, $4,795, €4,360, AU$7,100

• T Line Urban (4-speed gears, mudguards, 7.95kg) £3,950, $4,995, €4,590, AU$7,500

The bike is exclusively available via a ballot system on Brompton.com (opens in new tab) and through selected Brompton Junction stores in London, New York, Shanghai, Singapore and Paris, the bike will be available in two specifications, each with the option of a low and mid-rise handlebar fit.

Duncan has been writing about tech for almost 15 years and fitness ever since he became middle aged and realised he could no longer rely solely on his boyish good looks. He used to be on telly loads, but an unfortunate incident put a stop to that, so he now largely contents himself with telling people, "I used to be on the TV, you know."
Pre-lockdown Duncan was widely regarded as the best-dressed man ever to work for T3 – admittedly not saying much. Post-lockdown he is looking forward to wearing clothes other than shorts and hoodies again very soon, assuming he can still fit into them. He currently writes about cycling, fitness tech that isn’t too heavy, and all things kitchen and home related.