Vaunted Folding Bike Takes On Gravel: Brompton G Line Review

I’ve spent a lot of time over the years lugging my bikes up flights of stairs, shifting around elevators to give confused colleagues more space, or struggling to find a place in a building to park them where I wouldn’t have to worry about theft or damage.

So if you’re anything like me, you’ve looked at Brompton folding commuter bikes buzzing around the city and thought about how practical a bike that fits easily in the back seat of a car or under a desk must be. Long an urban commuting staple, Brompton folding bikes are known to be compact and reliable for darting around town, and simple to break down and pack away.

They have traditionally, however, only been practical for urban or suburban riding and commuting over smooth surfaces. And I’d much rather spend my scant free time on gravel paths or singletrack than baking in the Texas sun, competing with cars and pedestrians.

Finally, worlds have collided, as Brompton unveiled the G Line — a folding bike alternative for the gravel-minded. 

In short: The G Line, Brompton’s first rig geared for gravel, marks a considerable shift for the brand, adding much more versatility to its platform. The bike still fits under a desk or in the back of a car. But with beefed-up 20-inch wheels, disc brakes, and a snappy gearbox drivetrain, the G Line stands out as a comfortable, reliable, and rugged ride to and from the office and beyond. But there remain important tradeoffs to consider.

Roll over to GearJunkie’s guide to the Best Gravel Bikes to find your perfect ride.

Brompton G Line Review

Features and Spec

The Brompton G Line starts with a steel frame built up with 20-inch wheels, an eight-speed Brompton drivetrain featuring Shimano’s Alfine gearbox hub system, and a 54t chainring.

It includes hydraulic disc brakes, an aluminum fork with mounting bosses, and a roller rack that makes walking with the bike while folded particularly easy.

The bike comes in three sizes (small, medium, and large) that each have varying stem and seatpost lengths to account for a rider’s height.

For example, the stack on a small would come in at 677mm, 687mm on a medium, and 697mm on a large. Likewise, reach on a small would sit at 477mm, 483mm on a medium, and 504mm on a large.

Other features include front and rear fenders, wide platform pedals, and wide G Line handlebars for added stability, which is ideal for mixed-surface riding. It retails at $3,500 (MSRP) and comes in three colors: Adventure Orange, Forest Green, and Traildust White.

First Impressions

The Brompton G Line looked and felt bigger than I expected at first blush. That’s because it is.

Compared to the classic C Line, for example, the G line’s folded size is about 2.7 inches taller, 3.2 inches wider, and 5.4 inches deeper.

It also weighs a good bit more. The C Line ranges in weight from 24.91 pounds to 26.46 pounds, while the G Line starts at 32.6 pounds, nearly 6 pounds more.

The difference is pretty clear, but the necessity of those changes is immediately evident when you look at the bike’s wheels and drivetrain. The G Line’s 20-inch wheels include 140mm hydraulic disc brake rotors and come wrapped in Schwalbe G-One All Round 54-406 tires.

While they take up extra space, they provide grip and comfort over gravel and single track where smaller wheels and tires just don’t.

The Shimano Alfine Hub System houses the bike’s gears, keeping them clean and muck-free, while allowing for snappy and reliable shifts every time.

Those key features are what take the G Line from a normal folding commuter to one ready to perform in chunkier gravel and singletrack compared to its predecessors.

Brompton G Line: Test Impressions

The Brompton G Line almost immediately began exceeding my expectations. I stuck to the road to get a solid feel for the bike before getting a bit more into the rough-and-tumble.

The Alfine hub shifting system worked like a dream. Combined with its 54t chainring, the bike felt much more like a full-size bike than I thought it would. It was comfortable and quick, and even confidence-inspiring.

Once I moved into gravel and singletrack, the 20-inch wheels took rocks and roots in stride, providing a comfortable platform where I felt I could push myself.

I had been a little concerned about taking the G Line off-road. After all, it is a folding bike, and I certainly didn’t want it to fold while I was on it. But more than that, I expected to hear some rattling or feel at least some looseness after spending more time on chunkier terrain.

That didn’t happen. The bike remained quiet, responsive, and stable, and its folding points were utterly fixed in place when locked out.

When the bike is folded, its larger size and increased weight make it a bit more awkward to carry. However, the rolling rack allowed me to push or pull the bike by my side with ease, not unlike a carry-on suitcase. It still fit neatly under my desk, in the trunk of my car, or even in the back or front seat.

The bike essentially lived in my car for several weeks and gave me a chance to grab a quick ride any time I wanted, without having to deal with the headache of a bike rack, lowering my car seats, or having to lock a full-size bike somewhere outside.

Brompton G Line: Who’s It For?

When I was at home or planning a weekend ride, the Brompton G Line was not my bike of choice. I almost always opted for one of my full-size gravel bikes or even a mountain bike for longer rides.

However, the G Line occupied an interesting spot in my quiver that I didn’t really know I needed before. The logistics of taking a full-size bike to my office are just annoying enough that I don’t like to do it. The G Line didn’t require any major changes in my routine to cart around, so I found myself riding more often.

I can also see the utility in the G Line for riders whose commutes include stints on buses or trains, where getting a bike on or off can be a chore, or where taking up too much space can be an issue.

While the G Line is a little bigger and heavier than other Bromptons, I think its flair for adventure is more than a fair trade-off for those who want to split time between the tarmac and trails.