Brompton spent 50 years perfecting the 16-inch folding bike formula before throwing it out the window. The G Line Electric marks their first serious deviation from that recipe, swapping compact efficiency for 20-inch wheels and gravel aspirations. After extensive testing across city streets, gravel paths, and everything between, this bike reveals itself as both impressive evolution and expensive compromise. The engineering hits its marks, but the execution stumbles where it matters most.
Why 20-Inch Wheels Change Everything
The jump from 16 to 20-inch wheels transforms how this Brompton rides. Those extra four inches don’t sound dramatic until you hit cobblestones or bumpy bike lanes. The larger contact patch smooths out surfaces that make standard Bromptons feel like paint mixers.
Schwalbe designed the G-One Allround tires specifically for this bike, measuring 54mm wide with tan sidewalls. They roll surprisingly well on pavement while providing actual grip on loose surfaces. The tubeless-ready construction means you can drop pressure low enough to absorb trail chatter without pinch flats.
The Stability Factor
Wider handlebars and longer wheelbase create bike-like handling instead of the twitchy feel that characterizes smaller Bromptons. You can descend steep hills with confidence, though the geometry still reminds you this isn’t a mountain bike when things get technical.
This wheelsize shift comes with consequences beyond ride quality. The folded package grows noticeably larger, measuring 72cm high versus 65cm for a C Line. That’s the difference between fitting under train seats comfortably versus requiring more creative storage solutions.
The Electric System: Rear Hub Done Right
Brompton ditched their front hub motor for rear-wheel drive on the G Line Electric. The 250-watt motor sits invisibly in the rear hub, delivering assistance that feels more natural than the pushy front-drive system on C and P Line electrics.
The 345Wh battery mounts at the front in a purpose-built carrier bag. This positioning maintains Brompton’s signature handling by keeping weight centered over the front wheel. Some riders worry about the battery bouncing around, but the mounting system holds it secure even on rough trails.
The Range Reality Check
Brompton’s 20-40 mile range claim proves optimistic for most riders. Testing shows 25-30 miles at medium assist on mixed terrain, dropping to 20 miles if you use high assist aggressively. The standard battery feels undersized for the bike’s adventure marketing, especially compared to competition offering 500Wh+ capacities at similar price points.
The motor delivers consistent assistance without the surging character of some hub motors. Power ramps up smoothly from a standstill, preventing front wheel lift on steep starts. However, the 25 km/h cutoff arrives abruptly rather than fading gradually, creating an awkward transition when you exceed the limit on descents.
Hydraulic Brakes: Finally Standard
TRP hydraulic disc brakes with 140mm rotors replace Brompton’s traditional rim brakes. This upgrade transforms wet-weather confidence and reduces hand fatigue during long descents. The brake levers require less force while delivering stronger stopping power.
German testers specifically praised the braking performance in wet conditions, noting consistent power that rim brakes can’t match when soaked. The wider tires and disc brakes combine to create a bike that handles autumn rain without the sketchy moments that plague smaller Bromptons.
The downside appears during maintenance. Finding brake pads for TRP systems proves harder than sourcing parts for Shimano or SRAM setups. Some mechanics report sluggish service from TRP when warranty issues arise, though the brakes themselves prove reliable during testing.
How It Actually Rides
The G Line Electric feels planted and confidence-inspiring on pavement. Those wider tires and longer wheelbase eliminate the nervous handling that makes standard Bromptons exhausting on longer rides. You can hold a straight line through potholes and railway crossings without constant steering corrections.
Off-road capability sits somewhere between marketing hype and legitimate versatility. Smooth gravel paths and hard-packed trails work fine. The bike maintains composure on forest roads and canal towpaths where a 16-inch Brompton would feel sketchy.
Urban Commuting
The G Line Electric excels at daily city rides. Wider bars provide better control in traffic, while larger wheels roll over tram tracks and curbs smoothly. The upright position suits stop-and-go riding, though you sacrifice the nimble lane-splitting abilities of smaller Bromptons.
Technical Trails
Marketing images show the G Line tackling serious mountain bike terrain. Reality disappoints here. Loose, rocky climbs expose the bike’s limitations with its small wheels and limited gearing. The geometry works for fire roads but feels out of its depth on legitimate singletrack.
Long Distance Touring
The upright position proves comfortable for multi-hour rides, but battery capacity becomes the limiting factor. The 30-mile effective range forces planning around charging stops for anything beyond day trips. Riders attempting alpine passes report range dropping to 20 miles when climbing aggressively.
Folded Transport
The larger folded size complicates train travel compared to standard Bromptons. At 19.5kg with battery, carrying it up stairs or through crowded platforms requires genuine effort. The improved roller wheels help when pushing the folded bike, but can’t overcome the basic weight penalty.
Handling Quirks: The bike exhibits mild speed wobble above 35 km/h when descending without motor assistance. This likely stems from the combination of small wheels, relaxed geometry, and relatively flexible frame. It’s manageable but noticeable if you frequently exceed assist limits on hills.
The Gearing Compromise
Brompton limits the Electric G Line to their proprietary 4-speed system instead of offering the 8-speed Alfine hub available on non-electric models. This decision stems from motor integration requirements, but creates frustrating gaps between gears.
The 160% gear range spans from climbing ratios to decent cruising speeds, yet the jumps between each gear feel larger than ideal. You’ll often find yourself between gears, where one feels slightly too hard and the next slightly too easy. This becomes most apparent on rolling terrain where you constantly search for the right ratio.
Why No 8-Speed Option?
The rear hub motor occupies space where an internal gear hub would normally sit. Brompton chose to use their own derailleur system rather than develop a custom solution combining hub gears with the motor. This simplifies manufacturing and serviceability while sacrificing gear refinement.
Riders coming from bikes with 8+ speeds notice the limitation immediately. Those accustomed to single-speed bikes or 3-speed hubs adapt more easily, accepting the wider gaps as a fair trade for electric assistance.
The derailleur itself shifts crisply with minimal maintenance. The Microshift trigger shifter mounted under the right grip works reliably, though its position takes adjustment if you’re used to thumb shifters. Some riders report the cable routing creates friction that makes shifting slightly heavier than expected.
Folding: Still Brilliant, Now Heavier
Brompton’s three-point folding sequence remains unchanged, taking about 20 seconds once you learn the process. The G Line maintains the same steps: fold pedal, drop rear triangle, collapse front end. The result sits stable without external support, a key advantage over competitors that flop open without kickstands.
The heavier weight becomes apparent immediately when lifting the folded bike. At 19.5kg with battery, it requires noticeable more effort than a C Line’s 16kg. Carrying it up stairs, lifting into car trunks, or maneuvering through crowded spaces demands more strength than the lighter models.
Folded Dimensions Comparison
| Model | Height | Length | Width | Weight |
|---|---|---|---|---|
| C Line Electric | 64 cm | 58 cm | 27 cm | 16.0 kg |
| P Line Electric | 64 cm | 58 cm | 27 cm | 13.7 kg |
| G Line Electric | 72 cm | 67 cm | 41 cm | 19.5 kg |
Brompton added bearing-equipped roller wheels to make pushing the folded bike easier. This helps considerably when navigating train platforms or airport terminals. The wheels glide smoothly across hard surfaces, though they catch on carpet and rough pavement more than you’d expect.
Storage Reality: The G Line no longer fits easily under train seats or in overhead luggage racks. Plan for floor space instead, which becomes problematic during rush hour when trains fill up. The bike works better for car-based transport than public transit commuting.
The magnetic latch securing the folded package works reliably but requires more force to engage than on lighter models. The increased weight puts more stress on the magnets, occasionally causing them to pop open if you bump the bike roughly while carrying it.
G Line vs Conversion Kits: The Cost Equation
At £3,499 ($4,650), the G Line Electric costs significantly more than adding an electric conversion kit to a standard Brompton. Quality conversion kits like Swytch or Cytronex add electric assistance for £500-800, making the total investment around £2,000-2,500 for an electrified C Line.
Conversion kits save money but add weight in less optimal locations. Front hub motors create steering heaviness that affects handling, especially on the smaller C Line. The G Line’s rear motor maintains better balance by keeping weight low and centered.
Integration quality separates factory electric from retrofits. The G Line’s wiring runs internally, its battery mounts securely in a purpose-built location, and the system receives software updates through Brompton’s app. Conversion kits require external wiring, use generic mounting solutions, and offer limited support when issues arise.
The Warranty Factor
Adding conversion kits to Brompton bikes typically voids the frame warranty. If the frame fails or cracks develop, Brompton can refuse warranty coverage by claiming the kit caused excessive stress. The G Line Electric includes full warranty coverage for both frame and electric components, providing peace of mind worth considering in the cost equation.
For riders prioritizing the most compact fold and lightest weight, a C Line with lightweight conversion kit makes more sense. Those wanting the best overall package with proper off-road capability should seriously consider whether the non-electric G Line with its 8-speed hub gearing provides better value at £1,100 less than the electric version.
What Actually Works
Testing reveals several standout features that justify the G Line’s existence. The stability gains from larger wheels prove substantial for nervous riders or those frequently encountering rough pavement. Hydraulic brakes deliver confidence that rim brakes never could, especially when descending in wet conditions.
Genuine Improvements
The Compromises
Who Actually Needs This Bike
The G Line Electric serves a specific niche rather than replacing other Brompton models. It works best for riders who need occasional folding capability but prioritize ride quality over maximum compactness.
Ideal Scenarios
Better Alternatives Exist For
Maintenance and Longevity
The G Line’s increased complexity introduces new maintenance requirements beyond standard Brompton care. The electric system requires regular chain cleaning and lubrication like any e-bike, with the rear motor making this slightly more involved than hub-gear models.
Battery Replacement Reality: Brompton doesn’t publish official battery lifespan data, but lithium batteries typically retain 80% capacity after 500-800 charge cycles. Assuming 25-mile average range, expect battery replacement around 12,500-20,000 miles. Replacement batteries cost approximately £400, a significant expense to factor into long-term ownership costs.
Hydraulic brake maintenance requires bleeding and pad replacement at intervals matching regular bikes. Finding TRP-specific parts and service presents challenges compared to Shimano-equipped bikes. Some riders report 18+ month waits for warranty brake parts when calipers develop issues.
The derailleur system proves more robust than Brompton’s reputation suggests, though the exposed position makes it vulnerable during folding and transport. Hanger replacements cost £25-40 and should be carried as spare parts for tour riders.
Brompton Electric G Line
The Honest Bottom Line
The Brompton G Line Electric succeeds at what it actually attempts rather than what the marketing suggests. This bike improves the Brompton formula for riders who found 16-inch wheels too compromised but don’t need maximum portability. The larger wheels, stable handling, and proper brakes create a genuine bicycle feel that earlier Bromptons never achieved.
Yet the price demands scrutiny. At £3,499, you’re paying Brompton premium pricing for a bike that sacrifices their core advantage (extreme compactness) while not quite matching the capabilities of purpose-built gravel bikes. The battery capacity disappoints for a bike marketed toward adventure, and the gearing leaves you wanting more refinement.
Buy It If:
Skip It If:
For riders genuinely needing the specific capabilities the G Line provides, it delivers impressively. For most Brompton loyalists and folding bike shoppers, the standard C Line or non-electric G Line makes more financial sense. The Electric G Line works brilliantly for its narrow target audience while leaving everyone else questioning whether £3,500 buys enough performance to justify the compromises.
One practical consideration: at this price point and weight, investing in a high-quality U-lock becomes essential. The G Line’s 19.5kg weight makes it less tempting for opportunistic thieves to grab and run compared to lighter Bromptons, but the £3,500 value demands serious security when locking outdoors.
