Getting up to speed: Brompton gears explained

When it comes to picking a Brompton folding bike, we know there’s a lot of choice. Do you opt for the speedy P Line, the iconic C Line, or the rugged and adventurous G Line? We’ve got guides on all these bikes – including side-by-side comparisons – to help you make your decision.

But once you know the model that’s right for you, there’s still one choice to be made. What is the right number of Brompton gears? Like many things in life, the answer isn’t absolute – it depends on you and your circumstances.

While there may be a lot of options, the choice is actually pretty simple – and we’re here to help you through it. Actually, we’ve simplified our range of gear options recently, so there are fewer choices than you might once have encountered.

There’s certainly no need to feel overwhelmed when picking the number of Brompton gears for your new bike. We’ll cover why gearing matters, how it all works, and how to pick the best setup for you.

The Brompton gearing philosophy: more isn’t always better

One of the cornerstones of the Brompton philosophy is simplicity. Or perhaps it would be better to say efficiency. We don’t want you to pay for anything you don’t need, and certainly don’t want to build bikes that are overcomplicated.

That’s why we try to keep Brompton gearing systems simple.

The original Brompton was made for easy movement through the urban environment. Simple, fast and incredibly convenient. Just like the original C Line, modern Brompton bikes are tough, robust and versatile.

We keep things straightforward, so you don’t have to worry about what happens if you have a breakdown, nor do you need to spend hours maintaining your Brompton.

The number of gears a bike has broadly translates to how versatile or capable it is. The more speeds (another word used to mean gears) your bike has, the better it will be able to cope with a mixture of hilly and flat riding.

Internal vs external bike gears: what’s the difference?

Folding bike gear systems typically come in two forms. Internal hub gears, or external gears. But what do these terms mean?

External gears: This is the most recognisable gearing system for bikes and is commonplace on conventional road, mountain and hybrid bikes. A chain is fitted around a set of cogs attached to the rear wheel, and as the rider pedals, the chain propels the wheel forward.

A mechanical component called a derailleur moves the chain from one cog to another, making pedalling easier or harder. Generally, these systems are lighter than internal ones.

Our four-speed T Line, C Line and P Line models use an external derailleur gearing system.

Internal gears: Internal gearing systems are prized for the minimal maintenance they require. Inside the hub there is a set of planetary gears, which are small gears arranged around a central gear.

By changing which gears are engaged, the mechanism alters the ratio between the pedalling input and the rotation of the wheel. This changes how hard or easy it feels to pedal, just as an external system does, but all of the moving parts are sealed inside away from the grit and grime of the road.

Internal gears can shift when stationary, a nice feature if you want to change down to an easier gear when stopped, so that it requires less effort to get going again.

Our A Line, the most accessible Brompton, uses an internal three-speed hub gear. The confident, adventurous G Line uses an eight-speed internal gear hub – giving you a handful more options to choose from.

Combination internal hub and external derailleur: Now this one is really special. In our quest to make Bromptons even more capable, we set out to create a 12-speed folding bike.

To achieve this aim, our engineers came up with a way to combine a four-speed external derailleur with a three-speed internal hub – producing a final tally of 12 gears to choose from.

You will find this clever combo on our 12-speed C Line, P Line and T Line models.

Brompton gearing options explained

Now you’ve got to grips with external vs internal (and of course, the combination of both together), let’s look at how those systems are applied to our bikes.

One-speed
You’ll only find this option on the T Line. The removal of any extra gears is predominantly a weight-saving decision, and makes the T Line the lightest ever Brompton bike – just 7.45 kilograms. Simple, with zero maintenance required, and amazingly light and fast.

Used for: zipping around the city at speed, hopping on and off transportation with minimal effort.

Three-speed
The A Line is offered exclusively as a three-speed internal hub. The philosophy behind the A Line is to make a bike that is simple, useful and fun to ride. We think three speeds is enough for an A Line rider to explore the city, meet friends and get stuff done – without adding extra cost or weight. All you need and nothing you don’t.

Used for: easy integration into everyday life, short rides without too much climbing

Four-speed
There are more options to explore here, with four-speed options offered on our C Line, P Line and T Line models. The four-speed bikes use an external derailleur gearing system, which keeps things light with a crisp feeling to the changes. We think the four-speed option is best for performance, agility and taking on some bigger hills.

Used for: a good range of options covering riding fast on the flat and climbing the occasional hill

Eight-speed
The G Line is something entirely new for us at Brompton. It’s got larger wheels than other Brompton models, but can also take on more adventurous terrain. It made sense to give it good range of gears to take on varied terrain, and to enclose them inside the hub to protect the workings from the grit, grime and gunge you can encounter on your off-road escapades. That’s why the G Line has eight internal hub gears.

Used for: adventurous exploits, sometimes with the bike loaded with kit; enough options to get you up tricky steep ascents

12-speed
This is our newest innovation for Brompton bikes. You can find C Line, T Line and P Line models all with a 12-speed option – and these are the bikes that can take you the furthest and up the biggest hills. The system combines a three-speed internal hub with an external derailleur – giving you the best of both worlds when it comes to gearing options and choice.

Used for: almost anything, the biggest range and most versatile option; particularly great for tourers or long-distance cyclists

Fine-tuning your gear range

Fine-tuning your gearing can make a big difference to how your Brompton feels on the road. One of the simplest ways to adjust the overall range is by changing the chainring at the front. This is the large toothed ring that the pedals drive, and Brompton offers different options such as 44T, 50T and 54T.

A smaller chainring like the 44T lowers the gearing, which makes pedalling easier on climbs but reduces your top speed on flatter ground.
A larger chainring, such as the 54T, does the opposite. It raises the gearing, giving you more speed on the flat or downhill stretches, but requires more effort when the road turns upward.
The 50T sits comfortably in the middle and is often chosen as the standard balance between climbing ability and speed.

Choosing the right Brompton chainring size comes down to your own riding conditions and preferences. If your daily route takes you across a hilly city or you know you will be carrying luggage on the front carrier block, you may appreciate lower gearing that keeps climbs manageable.

If you want an efficient Brompton gearing for hills, where the focus is on steady, comfortable pedalling without grinding up each slope, we’d advise the smaller 44T chainring. On the other hand, if your rides are mostly across flat terrain and you like to push the pace, the higher gearing of a 54T can help you cruise at speed without spinning out.

Your fitness and riding style also matter. Stronger riders may enjoy the challenge and efficiency of higher gearing, while those who prefer a relaxed ride may be happier with the lower options.

Cadence plays a role here too. Cadence simply refers to how quickly you turn the pedals, and most riders find there is a natural rhythm where pedalling feels smooth and sustainable. The right gearing allows you to stay in that rhythm whether you are climbing, cruising, or accelerating away from the lights.

Gear up for your next Brompton adventure

Choosing the right Brompton gears is all about personal preference and intended use. You can see it as a way of personalising your ride experience so that it suits you perfectly.

Having the right gears on your bike will unlock its potential, allowing you to do what you want, how you want.

Whether you’re a 12-speed long-distance tourer kind of person, or a relaxed three-speed urban explorer, or a four-speed bit-of-everythinger… there’s a Brompton gearing setup to suit you.

If you are stuck between two options, you can always visit a Brompton dealer and take a test ride. If you’re already set on a particular speed, choose one below and start shopping.

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