Bike test: Brompton T-Line One

A foldable bicycle stands on a cycle path
The Brompton T-Line One
Bromptons have always been super compact but never especially light. Until now. Dan Joyce tests one of the new titanium models

The Brompton T-Line is much lighter than the part-titanium Superlight, now called the P-Line. That has a steel main frame; the T-Line's is titanium. With a carbon fork and lightweight bits, it weighs as little as 7.5kg.

This makes a palpable difference when you pick it up – which you do a lot with a folded Brompton, as you carry it onehanded onto trains, into buildings, and so on. While it also feels a bit peppier to ride, the main benefit is portability.

There are two versions of the T-line: the Urban (£4,415, 7.95kg), which has a four-speed derailleur, mudguards, and a front luggage block; and the spartan, singlespeed One. I'd have preferred to test the Urban as a Brompton is impractical without mudguards; its raison d’être is short-distance utility trips. It wasn't to be.

The T-Line’s main frame has a larger diameter tube (51mm) than a steel Brompton (45mm) to compensate for the fact that titanium isn't as stiff as steel. Its hinge has a tongue-andgroove joint rather than flat faces. The end result is that the T-Line feels stiffer when riding out of saddle, something the One's single gear makes inevitable.

The Brompton bicycle in it's folded state. It is folded up on itself three times to stand saddle-up on the ground in a compact size

The T-Line’s reach – by which I mean: saddle clamp to handlebar clamp distance – is slightly longer than the last Brompton I tested, so the riding position is a bit more athletic. Otherwise it’s standard Brompton geometry, right down to the overly low trail figure that gives the bike its characteristic nippy/nervous (delete to taste) handling.

It folds in the familiar Brompton way. The hinge catches have stops on the ends of their bolts (finally!) so can’t unscrew and fall out. The left-hand pedal doesn’t fold but quick-releases, presumably to save weight. The Advance chain tensioner is simpler than the double-jockey-wheel model, so rear wheel removal and fitting is easier.

Riding performance is like any Brompton, just sportier. Much of that is down to the Schwalbe One tyres, whose rolling performance eclipses Marathons and even Kojaks. Small wheels benefit more obviously than big ones from good rubber as their rolling resistance is higher to begin with.


Four grand is a huge sum but, unlike a Sunday-best bike, a T-Line might be used daily and (judging by other Bromptons) last longer. If you have deep pockets and want the improved portability a titanium Brompton offers, why not?

Other options

Hummingbird Single-Speed £3,495

A bright yellow folding bicycle

Much longer when folded (117×60×20cm) as there’s no hinge in the carbon frame, but even lighter at 6.9kg. Will need mudguards etc.

Bike Friday Pakit $1,895 (£1,562)

An aqua-blue folding bicycle

Buying direct from the USA means adding shipping (~£330) and import duty (~£530). It weighs about 10kg but with custom options (singlespeed etc) can be 7.3kg.

Our test promise

At Cycling UK and Cycle magazine, we are proudly independent. There’s no pressure to please advertisers as we’re funded by our members. Our product reviews aren’t press releases; they’re written by experienced cyclists after thorough testing.

Tech Spec

Brompton T-Line One £4,180

The dimensions of the Brompton

Sizes: one size.

Weight: 7.54kg (as shown).

Dimensions: 64.5×60×32cm (claimed); 61.5×58.5×29cm (measured).

Frame & fork: Grade 9 titanium main frame with integrated headset. Superlight Advance titanium rear triangle with 54mm roller wheels. Full carbon fork with magnetic pedal holder. Fittings for mudguards, lights, front carrier.

Wheels: 35-349 Brompton Schwalbe One tyres, Superlight wheels (349×17 Presta-drilled aluminium rims. Front: 74mm hub with 20 radial, doublebutted spokes. Rear: 112mm hub with 28×1 double-butted spokes).

Transmission: Superlight CNC aluminium pedals (left QR), Superlight carbon chainset with 170mm cranks and 50t chainring, FSA Mega Exo bottom bracket, YBN 10-speed chain, Brompton Advance chain tensioner, 12t sprocket. One ratio: 69in.

Braking: Brompton brake levers and sidepull callipers.

Steering & seating: Superlight lockon foam grips, 560×31.8mm Superlight carbon handlebar, Grade 9 titanium stem. Superlight saddle with carbon rails and base, 520×32mm Superlight seatpost with carbon core and 0.3mm steel ‘armour’ and pentaclip mount, aluminium seat clamp.

Equipment: bell, rear reflector. 

* 71° effective