Brompton G Line folding bike
The G Line - Gravel? Line range was originally introduced by Brompton in autumn 2024 with the 2025 lineup of bikes
It has larger wheels than the traditional 16 inch Brompton size at 20 inches
Brompton G Line specification:
1. Frame
Main frame: | Steel |
Rear frame / triangle: | Steel |
Handlebar stem: | Alloy |
Front forks: | Alloy |
Folded size: 71cm wide x 68cm tall by 38cm deep (approx)
2 Colours
For the 2027 model year there is a choice of the following colours:
- Space Black
- Forest Green
- Brompton Blue
- Lake Grey
Adventure Orange and Traildust White colours are no longer available from the factory
Main frame: | Based on colour choice |
Rear frame / triangle: | Based on colour choice - to match main frame |
Handlebar stem: | Black |
Front forks: | Based on colour choice - to match main frame |
Decal: | Depending upon colour choice |
3. Size
Unlike the traditional 16 inch wheel size Brompton, the G Line comes in a choice of 3 sizes:
- Small
- Medium
- Large
The G Line only has one handlebar type - ride position is dictated by the stem length and seat post length
Handlebar width - 65cm
4. Gears / drivechain
8 speed Shimano Alfine hub gear system with single 20T rear sprocket
Square taper bottom bracket
54T front chainring - black (also available as 50T or 44T - we can change at no extra cost)
Brompton advance chain with connecting link - 114 links
Brompton flat platform pedals (the right one is removable)
5. Front luggage system
The G line comes with a front carrier block fitted
6. Mudguards / Rack
This bike comes with black mudguards and rack
7. Roller wheels
New larger roller wheels help keep the bike stable when folded
8. Wheels / Tyres / Brakes
20 inch wheel size - ETRTO 406
TRP / Tektro hydraulic disc brakes
The wheels have black hubs, black spokes and black rims
Presta / racing type valve
Schwalbe G One with tan wall (ETRTO size 54-406) - tubeless ready
Low rolling resistance and good puncture protection
If you would like to change to Continental Contact Urban tyres for lower rolling resistance and designed primarily for on-road use - we can make this change at no additional cost (note that the Contact Urban tyres can not be made tubeless)
9. Saddle
Brompton saddle
The saddle connects to the seat post using a Brompton Pentaclip allowing adjustment forwards and backwards as well as the ability to rotate to give an extra inch of saddle height should you need it
10. Seat post / height
Black steel seatpost
On the G Line - the seat post hight is determined by the bike size:
G Line size | Seatpost |
Small | Standard length |
Medium | Extended length |
Large | Telescopic |
11. Suspension
Along with the new G Line comes a new advance suspension block
12. Lighting / reflectors
Front and rear reflectors are included
It's easy to retrofit battery lighting such as:
- Brompton Cateye VIZ150 rear light - mounts on the Brompton saddle
- Brompton Lezyne G Line front light with bracket
- Brompton G Line Be Seen light set
| Colour | Lake Grey, Brompton Blue, Space Black, Forest Green |
| Size | small, medium, large |