After a long wait, the bike arrived well packaged set up and with extra tools. Definitely worth the wait and would purchase from Sigma again. Communication was very good throughout the purchase.
Product Details
Brompton G Line 8 Speed Folding Bike
Expertly engineered to go where others can't, the G Line 8 Speed Folding Bike is the first Brompton to deliver the ride feel of a full-size bike. With brand-new geometry, 20-inch wheels, and game-changing comfort and capability, it redefines what a folding bike can do. Every detail is designed around Brompton’s iconic fold, making it the perfect one-bike solution for the city and beyond.
Brompton G Line Features
The Brompton G Line is built for versatility and performance, featuring a range of innovations that enhance comfort, control, and durability.
Its solidly built 20-inch wheelset is large enough for any adventure yet compact enough to fit within the fold. Custom-made puncture-resistant tyres ensure reliability on varied terrain. Hydraulic disc brakes provide super dependable stopping power, making this the first Brompton equipped for all-weather, all-terrain riding.
The wide platform pedals offer exceptional grip and comfort, with the left-hand pedal designed for quick release to make the bike even more compact when folded. Custom-made wide handlebars deliver outstanding stability, whether climbing, navigating rough ground, or enjoying longer rides. Ergonomic grips ensure that every touchpoint between rider and bike is optimised for comfort and control.
The Brompton G Line is available in three sizes: small, medium, and large, based on rider height. Its single-size frame features different stem and seatpost heights, developed and tested with a world-leading bike fit expert to ensure the best possible ride experience.
Features
- Weight: From 13.9 kg
- Speed: 8 Speed
- Material: Steel
- Folded Size: 72cm (D) x 67cm (H) x 41cm (W)
- Main Frame: Hand-brazed steel
- Rear Frame: Steel
- Fork: Aluminium with mounting bosses
- Grips: Ergonomic grips
- Seatpost: Small - Standard Black, Medium - Extended Black, Large - Telescopic Black
- Saddle: Superlight
- Seatclamp: G Line Aluminium
- Hinge Clamps: Self-aligning hinge clamps
- Pedals: Wide platform
- Drivetrain: Brompton 8-speed drivetrain
- Number of Gears: 8
- Chainset: 54T
- Headset: Brompton headset
- Shifters: Microshift
- Derailleur: Shimano Alfine hub system
- Rear Wheel: 20"
- Front Wheel: 20"
- Tyres: Schwalbe G-One Allround 54-406, tan wall
- Lighting: Reflectors
- Brakes: Tektro hydraulic disc brakes with 140mm rotor
- Front Carrier: Large diameter front carrier block adaptor for all types of Brompton luggage
- On-Bike Accessories: Roller Frame and Bell
Highlights
- 8 speed drivetrain
- Shimano Alfine Hub System
- Steel Frame with Aluminium Fork
- 20" Wheels
Specifications
- Model
- G Line 8-speed
- Brakes [Kind]
- Hydraulic Disc
- Brakes [Maker]
- Tektro
- Brakes [Model]
- Tektro hydraulic disc
- Chainring [Gearing]
- 54
- Discipline Compatibility
- Road, Commute, Travel
- E-Bike
- No
- Family
- G Line
- Fenders Mounts
- Yes
- Fork [Brake Type]
- Disc
- Fork [Material]
- Aluminium
- Fork [Wheel Size]
- 20"
- Frame [Material]
- Steel
- Frameset
- No
- Gearing [Configuration]
- 1x
- Gearing [Kind]
- Conventional
- Gender
- Unisex
- Handlebar [Kind]
- Flat
- Handlebar [Shape]
- Flat bar
- Headset [Maker]
- Brompton
- Rack Mounts
- Yes
- RD [Maker]
- Shimano
- RD [Model]
- Shimano Alfine
- Shifters [Maker]
- Microshift
- Shifters [Model]
- Microshift
- Shifting
- Mechanical
- Sub Family
- G Line 8 Speed
- Suspension Configuration
- Rigid
- Tires [Maker]
- Schwalbe
- Tires [Width]
- 54 mm
- Wheels [Configuration]
- Front+Rear
- Product code
- 1898441 / 54294113026394
Size Guide
| Size | Small | Medium | Large |
|---|---|---|---|
| Rider Height | 152 - 168cm | 168 - 183cm | 183 - 198cm |
| Stack (MM) | 677 | 687 | 697 |
| Reach (MM) | 477 | 483 | 504 |
| Seatpost | Standard | Extended | Telescopic |

Reviews
This G Line is an excellent bike, stable rides like a full size bike. Tires are excellent for UK pot holed roads. However if you are a commuter on tube or train, then the size and weight of bike is a consideration. Its 30% bigger than the traditional brommies (s p t line etc), it weighs more and is heavy to lift. So Id think very carefully about Tube (underground). And over land trains its going to be a nuisance to other commuters. The folded wheel function is great, but on a train the bike can easily roll around. Somethings to consider.
Shipping & Returns
Free UK delivery on orders over £50. Orders are dispatched within 1-2 working days and typically arrive 1-2 working days later.
Return unused items in their original packaging within 30 days of delivery. Return postage is £3.50.
Q & A
2 questions answered
Im 182 cm. Do I buy the line med or large
Hi there, Please contact the sales team for help with this, Many thanks Joe W
On the small size, what’s the maximum height from centre of bottom bracket to top of saddle?
Hi there, Please contact the sales team for help with this, Many thanks Joe W









