The Brompton Electric G-Line folding e-bike is adventure ready [Review]

The Brompton Electric G Line bike from the UK-based brand is a positioned as a off-road folding electric bike. Since 1970, Brompton has been making portable and foldable commuter bikes, and just last year they introduced their first non-electric bike designed for riding off the beaten path. 

Now, Brompton is taking things a step further with their electrified G Line. A 345Wh battery paired with a rear 250W rear hub motor can assist riders up to 20 mph for up to 50 miles of riding off road.

I met the Brompton team at the Sea Otter Classic bike festival in April, and took a quick test ride on the Electric G Line. I was hooked after spinning around on some dirt paths, and I asked if this bike could handle mountain bike trail abuse. While they did not give me a definitive yes, a rep told me the bike can withstand urban and “light trail” environments. Challenge accepted. 

A few months later, a Brompton Electric G Line bike showed up at my door. I am used to receiving test bikes in big boxes, so the small shipping box for the Brompton surprised me. It was about half the size of a standard medium mountain bike shipping cardboard box, and just a bit wider. The bike was folded inside, of course, and it was easy for me to lift and take the bike out. If you live in a small home, getting a bike delivered should be an easy task.

Brompton Electric G Line specs

I’m 5’8” and decided to test a size medium bike. The medium has a stack height of 687mm and a reach of 483mm. The frame’s front and rear triangles are made with brazed steel while the fork is aluminum with bosses for accessories. A telescopic seapost allows for easy adjustment, and the build does not come with a dropper post. However, as you can see here, at least one rider has figured out how to add a dropper to the G Line.

The bike comes equipped with one quick-release pedal and another that’s threaded on. I knew these plastic pedals weren’t going to cut it for my testing, so I decided to unthread them and throw on my mountain bike pedals. I also removed the preinstalled ergo grips and opted for my favorite ODI grips. This G Line is the first ever Brompton to get hydraulic disk brakes — Tektros — with 140mm and 160mm front and rear rotors, respectively. Yes, the front rotor is smaller than the rear.

For gearing, Brompton went with a one-by set up. The drivetrain features a 50 tooth chainring up front with a Brompton-branded, 4-speed derailleur at the rear. The four cogs — 11T, 13T, 15T, and 18T — allow for a 163% gear range. The UK must not have big hills like we do here in California! To top things off, a set of 20″ Schwalbe G-One All Around Tan wall tires gives this bike the trail capability and comfort that differentiate it from the rest of the Brompton road-specific models.

Taking it to the trails

I really wanted to see if this Brompton deserves to wear 20″ Schwalbe G-One knobby tires. So, I decided to test ride it on my local trails where I typically ride all of my mountain bikes. This park has green, blue, and black-diamond rated trails.

The bike can fit the trunk of most vehicles when folded, but I opted to transport it in my truck’s bed. Loading and unloading it was pretty easy with the battery removed. When the battery is on the bike, with pedals the bike weighs 42.6lb on my scale. Without the battery, the bike weighs about 35.6lb. Those are pretty hefty numbers for a small bike, but then again the bike is made of steel and aluminum, after all.

I had hoped I could unfold the bike without having to read any instructions. My advice: read the instructions or watch this how-to video. After a few tries, I started to get the hang of it. Folding it up follows a similar but process in reverse.

Hitting the trails on the Brompton Electric G Line folding bike

Finally, it was time to ride! I turned the bike on using the battery buttons up front and selected my level of assist. I started at three out of three since I knew the gearing wasn’t going to get me up the steeps. On flat ground, the bike picks up speed pretty quickly, and the small diameter tires help with quick acceleration.

I headed for my first short and punchy, steep climb. The G Line climbed surprisingly well and the rear hub motor helps overcome the limited gearing. I needed to anticipate climbs and carry momentum while getting out of the saddle half way through. If I stopped pedaling in a steep climb, the rear hub motor would cut the assistance, which is not something I’m used to coming from mid-drive electric bikes. I don’t really want to make the comparison between the two but it’s fair to mention this disadvantage. 

I got to the top a bit more exhausted than usual but hey, I was pretty surprised at how well the bike performed on the way up. Honestly I don’t think I could have made it up without the motor assistance. But the most notable thing about my first climb was the number of confused looks I got from other riders!

It was now time to see how the G Line performed on the descents. Its first test was a mix of blue and single black-diamond trails. I aired down the tubed-tires a bit and began the first descent. The ride was of course bumpier than usual, but I felt in control. The small knobby-ish tires offer enough grip to keep the bike planted while the Tektro hydraulic disc brakes do a great job maintaining a comfortable speed. The bike felt, well, like a regular bike would feel.

The externally routed cables did rattle quite a bit, along with the battery and fenders. The sound was most noticeable while going through rock gardens! Halfway through a technical trail section, to my surprise, I wasn’t struggling to stay alive on this small foldable bike. Rather, I found myself choosing lines and blasting right through them. Tight turns and maneuvers felt snappy thanks to the bike’s tight turning radius and the Brompton kept its composure when leaning the bike sideways. I even hit some tiny jumps just for the fun of it. At the end of the trail, I couldn’t believe that the G Line did such a good job at getting me down the trail.

Once I knew the bike could survive that, I rode it on some other favorite trails. At some point I got used to the riding characteristics of the bike and I became more comfortable. I even rode it at the nearby pump track, which was a blast! Since I had lowered the seatpost a bit, the exposed end at the bottom would drag in the dirt sometimes, but all I had to do was raise the post above the chainring. It was definitely a different riding experience compared to a full-size bike — and fun too.

At the end of my 12-mile ride, I had about 35% battery remaining, and I got in a perfect afternoon session at my local trail park. At home, I plugged in the 2A charger which can charge the battery from 0% to 100% in about four hours. A companion mobile app offers over the air updates along with live data while riding in case the Smart Control screen is too small to read.

Who is this bike for?

There is so much to love about the Brompton Electric G Line. This is an unusual trail bike that will compliment a specific lifestyle. While my testing may have been a bit brutal and out of the ordinary for this type of bike, it showed that Brompton didn’t just throw some earthy matte colors onto an existing frame along with some bigger trail friendly tires. They re-engineered a folding trail bike from scratch anticipating that riders might get themselves into uncharted territory.

The electric assist system is well integrated with the famous Brompton folding mechanism making it easy to stowaway at home, in a vehicle, or under a desk at work. There is plenty of power to get riders around town and through dirty roads. While I wouldn’t say the G Line is a performance trail bike, I can say that this bike can suit a lot of casual riders looking to bike off the pavement and venture onto dirt roads. Even as an avid mountain biker, I would love to keep this for camping trips where my full-size bike can be cumbersome to bring along.

Folding and unfolding the bike definitely requires a learning curve for first timers. Its weight is quite surprising for its size but is reasonable for an e-bike. I wish Brompton could have fit a few more sprockets on the cassette to give the bike more climbing capability, along with possibly a smaller chairing up front, something between 40T and 46T.

My biggest gripe is the included quick release plastic pedals that apparently cost $126.50. While I understand the quick release pedals are proprietary Brompton Tech, the pedals should definitely have metal pins or at least offer the option for them. My feet would slide all over them when things got wet and muddy. Luckily, these pedals can be unthreaded and replaced with your preferred set. 

Speaking of pricing, the Brompton Electric G Line costs $4,950 USD. Compare that to a full size commuter/light trail electric bike like the Specialized Turbo Tero 3.0 that is on sale for $1,999.99 USD, that can do the same if not more than the G Line. But the Tero doesn’t fold to a compact size like the Brompton. Brompton knows this and is betting that folks who need a capable and easy-to-store bike will be willing to pay a premium. With slim competition in this niche segment, the Electric G Line is quickly selling out, so it seems there is a demand for a bike like this. 

The bike folds down to a 28.3×26.2×16″ size that can be rolled anywhere. This ability alone will be a huge selling factor for buyers looking for something compact. Many apartment owners/renters lack space for a full-size bike and may look for the convenience that a Brompton offers. This can mean more people on bikes! I’m all for it. 

Pros

• Compact size lets you take/store almost anywhere
• Robust frame can take on adventure
• Built in lights are bright and run off of main battery

Cons

• Gearing best suitable for flat and not so steep hills
• Plastic OEM pedals don’t keep feet in place in wet conditions

Bottom line

I’ll be honest, I judged a book by its cover and re-learned that I shouldn’t. The Electric G Line didn’t let me down and proved itself to be capable in uncharted territory. It may look toy-size, but I can tell you that the bike almost rides like a full-size bike. Though you may get a few stares out on the trails, you can feel good knowing you are riding a bike that’s designed, engineered, and built by an established bike brand. If you have been looking for a robust and compact electric bike to rip around town, on backyard trails, or for road tripping, this little guy may be for you. 

You can buy the new Brompton Electric G Line from Brompton or REI in Adventure Orange (pictured), Forrest Green, or Traildust White. And if you like what you see but would rather not have electric motor assistance, check out the non-electric G Line here.