Electric Brompton Buyer’s Guide
The A to B Electric Brompton Buyer’s Guide covers the four key Brompton power-assist conversion kits and Brompton own electric bike. We have unfortunately had to drop our Folding Bike and Electric Bike Buyer’s Guides because there are now so many bikes and change is so rapid, it’s just not feasible.
A to B Buyer’s Guide – Top Five Electric Brompton bikes
1. Cytronex C1
Price: From £1,073 (kit only) Rating: 5/5 Verdict: “Exquisitely designed…”
Cytronex-Brompton
Are we serious? Is a small company in Winchester really turning out the best power-assist system currently available for the Brompton? It’s a subjective thing, and Bromptons get used for all sorts of purposes, but taking into account weight, price, efficiency and user-friendliness, this really is a cracking option, and well worth putting on anyone’s short-list.
For years, Cytronex made a very practical power-assist kit based on the Tongxin motor, still used in the Nano-Brompton. But MD Mark Searles was quietly developing something much more sophisticated, and the C1 was finally launched in 2017 to some acclaim. Before long there was a Brompton variant too. It’s not the cheapest kit-based solution, but certainly not the most expensive, and it’s quiet, sophisticated and efficient, in fact better than many factory-built electric bikes. We have just tried the special C1 T-Type Brompton kit, which is custom-made to fit the new all-titanium Brommie. The complete package, with 198Wh battery, weighs only 11.7kg, which is breathtakingly good… For the range you’ll have to read the full article.
There must be a few complaints? Only one really. The ‘waterbottle’ battery stands quite high over the frame tube, so it’s more difficult to get your leg over (stop sniggering at the back). We’d like to see a ‘pannier’ shaped battery hanging over the tube.
We have road-tests of the early C1 in A to B 118, fitted to a Brompton in A to B 127 and A to B 132, and to the T-Type Brompton in A to B 136
2. Nano-Brompton 2.1
Price: From £820 (144Wh kit) Rating: 5/5 Verdict: “Now a touch old-tech, but great value…”
Nano-Brompton
For three years after its inception in 2007, the Nano was one of our top recommendations, but it later moved down to a 4-star rating following persistent feedback of battery issues and other quality control problems. For 2012, the Nano returned as Nano 2.0, which has proved lighter, slicker, and more reliable, and was later revised as the 2.1 and bounced back to 5 stars with us. The key change was to Ping batteries, and now 360Wh Hailong. These weigh 4kg, and if you want a cheaper conversion with a battery weighing little more than 1kg, there is the option to fit a 144Wh garden appliance battery, generally Bosch. The Nano 2.0 and later variants have the control electronics positioned low down near the front pannier block rather than high up on the handlebars. This looks clumsy if you ride without a front pannier, but you’re unlikely to, because the pannier holds the battery…
Gross weight (including the separate pannier-mounted battery) is a reasonable 15.8 to 18.5kg, and you only have to carry 12.5-14.5kg in one hand. The wide range comes down to the Brompton model used and the size of the battery. The motor is whisper quiet, a capable hill-climber, and we managed to go 45 miles on a charge, but this was our first test of a prototype fitted with a large battery and a motor designed for a 26-inch wheel. so it was geared for less than 10mph on a Brompton wheel. That’s a very good way of getting extra mileage! Expect 15-30 miles from the big battery, or 8-20 miles depending on terrain from the small one.
Thanks to Euro-chicanary, most manufacturers have stopped fitting twistgrip throttles, but they have always been legal with a pedal movement sensor and Nano offers a twistgrip or thumb-lever as an option. In early 2025, the UK Department for Transport gave the green light to fitting twistgrip throttles to any bicycle – this option is highly recommended.. Do take our advice and pay a modest £30 extra for the thumb-lever or twistgrip versions (the nice Nano people can show you how this works). We didn’t like the automatic control one bit, as with most of the cheaper types.
The Nano isn’t quite the discount option it once was, but it’s a reasonable price for a straightforward power kit with a good track-record. The 12-month battery guarantee is looking on the low side these days too, but overall it’s a good little machine, so it stays near the top of our electric bike wish list.
A nice option is factory fitting of the kit for an extra £100… well worth it for the electrically or mechanically challenged.
The Nano kit can be fitted to any bike for a hundred quid less than the Brompton version.
A folding electric bike that still outclasses most of the options.
Full review of the Nano-Brompton. We have also published two follow-up tests (see back issues), a full review of the Nano-Brompton 2.0, and the 2017 spec bike is reviewed in A to B 117
3. ARCC-Brompton
Price: From £1,899 (home-fitted 144Wh kit) Rating: 4/5 Verdict: “Hard to fault, but not quite in Cytronex territory…”
An interesting outfit, and an interesting product, if a bit expensive. It’s all good quality stuff, and mostly well engineered, but with a few tedious little niggles like the lack of a light on the control unit and some slightly tricky ergonomics. We said in our test that it feels a bit like a Sunday morning toy rather than a serious tool for commuters, and that sums it up quite well. Unlike the Cytronex and Nano, the battery goes on the front carrier block, so no luggage capcity. ARCC has close links with Moulton and is best known for its Moulton kit, which perhaps fits with the enthusiast side of things.
Weight-wise, when we test things, we’re at the mercy of the kit manufacturers, who tend to supply one with lots of gears and extras, presumably to massage the journalistic ego. Our test bike weighed 17.7kg complete with Bosch 6Ah (216Wh) battery, but ARCC had chosen a 6-speed with an extended steel steat-pillar, so that’s a bit pessimistic. With the tiny 2Ah battery and a lighter bike, you might see 15.6kg, but we found the little battery had a range of barely 7 miles. The 216Wh gives 20 miles, which is OK, but not exactly in Cytronex territory.
The full review of the ARCC-Brompton is in A to B 129.
4. Brompton Electric
Price: From £2,995 (complete bike) Rating: 3/5 Verdict: “A disturbing number of teething troubles.”
Brompton Electric
The factory-made electric Brompton was under development for several years, possibly even a decade. The problem with that sort of gestation is that the public either lose interest, or the bike ends up featuring a pile of ten-year-old technologies and no-one wants it either way. Both of these things have happened here to some extent, and the development road continued for many months after after the launch, with a variety of issues surfacing.
What you get is a 2, 4, 6, or 12-speed Brompton with crank-mounted torque sensor and Brompton’s own front wheel motor. Weight is from around 17kg (our 6-spd test-bike weighed 17.3kg), but that includes the battery pannier, which weighs 2.9kg, so like the Nano, you should never need to carry the whole lot in one hand – a big advantage.
Very briefly, with bad news first, Brompton’s motor is noisy by modern standards (yes, it would have been OK a decade ago), there are still a variety of software and hardware bugs (dirt on the bag connector is behind most issues), it only comes with one size of battery (unlike the Nano above), and most seriously, you cannot fit a standard Brompton front pannier to the bike, or use the electric front pannier(s) with a normal Brompton… as you can on the Nano, of course. Not the end of the world, but it leaves you with only two options: an impossibly tiny luggage space as standard, or a reasonably capacious bag for an extra £130.
Reliability issues do still occurr unfortunately. There have been motor failures, control-system failures, and some people just don’t like the pedal torque-sensing system. It’s sensitive to different pedalling styles, so make sure you have a decent ride before buying one. And there have been incidents when pedalling strongly at a low cadence, which can cause an unexpected rush of energy from the motor, provoking front wheelspin… not good.
Early failures like overheating seem to have passed, but there are still some daft practical issues. You can’t easily change power or light settings on the move, because the battery top ‘dashboard’ is too far away, and who decided to make it impossible to fit a normal bag? Were they mad?
The good news is that the electronics are fundamentally well sorted now, as they should be with Williams F1 involvement, it’s covered by Brompton’s dealer network and warranties (unlike aftermarket options like the Nano and Cytronex), the auto-lights are good, power output is muscular and reasonably controllable (but don’t try reaching for the control buttons on the move), and the price is acceptable.
The bike looks and feels like a product that will last. Not a world-beating design like the original Brompton, but a good solid performer if they can remove the final niggles. In our estimation, it edged ahead of the Nano in late 2018, but has dropped back since. The choice really depends on your views about bags, cost (Nano can convert your own bike, for example) and warranties.
This really should have been the king of the electric folders, but it’s a bit of a lemon.
We have two reviews of the Brompton Electric – a very detailed early test in A to B 117 from August 2017, and a follow-up looking at the production version (hopefully the definitive version!) in A to B 122 in November 2018
5. Swytch-Brompton
Price: From £1,250 (kit only) Rating: 2/5 Verdict: “A lot of money for a pretty low-tech affair…”
Yes, a bit pricey at £1,250, but the Swytch kits are half price if you are willing to pay upfront before they’ve been shipped or even MADE over there in China. Surely one would be a fool to do that? And a fool to pay £1,250? All true. That price has no basis in the real world, but what brilliant marketing… Price aside, this thing works tolerably well, but you are carrying a big 2kg battery around on the handlebars, which is not the smartest place on a small-wheeled bike. The whole kit weighs 3kg, so expect your finished e-Brompton to weigh 15kg to 18kg according to model. Range came out at 13.6 miles. That’s pretty good and reasonably efficient, but you have to carry a 180Wh battery around on your handlebars to see that sort of mileage.
Our Swytch-Brompton road test is in A to B 120
