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Dahon Unio E20 electric folding bike review

7 Apr 2022

A punchy electric folding bike with plenty of functionality for its price, but tricky to carry, lacks lights and can be unstable at speed

Cyclist Rating: 
Powerful assist • Easy to fold • Large number of gears helpful on hills and when assist is off • Seatpost battery helps aesthetics
Handling is twitchy at higher speeds • Tricky to carry • No integrated lights

The Unio E20 is the latest electric folding bike from US brand Dahon. It features a hidden seatpost battery, lightweight mid-motor and 9-speed gearing.

Named for its 20in wheels – and presumably the Latin translation of 'union' – the Unio E20 offers most of the features you'd expect, but at half the price of most of its competitors.

Dahon's experience in folding bike manufacturing means the Unio E20's folding process is slick and easy. Plus, its electric assist offers an at-times explosive kick, while the battery is neatly hidden in the oversized seatpost.

Producing parts in-house, including the 36V 200W motor and most of the drivetrain, has meant the Unio E20 ticks most of the same boxes as the more premium options but without as hefty a pricetag.

However, placing most of the weight at the rear of the bike does mean it can feel unstable at higher speeds, and you'll want to spend some of your leftover cash on bike lights.


Dahon Unio E20 vs. Brompton, GoCycle, and Hummingbird

Named after its founder laser physicist David Hon, who created his first folding bike in 1982, Dahon has produced bikes under its own name as well as the Novara brand for US outdoor brand REI.

Dahon has made a wealth of folding bikes in its time, once claiming to take up over two-thirds of the market, but with electric-assist only coming through in recent years it has had to develop that technology alongside everyone else.

Dahon has seen competitors like Brompton successfully bridge across to the electric world through a collaboration with F1 team Williams and other electric-only brands such as GoCycle gain popularity.

Priced at €1,875 (approx £1,570) though, the Unio E20 undercuts the more premium but dominant Brompton, GoCycle and Hummingbird. A Brompton Electric starts at £2,995 and is the cheapest of the three.

Instead, it occupies a middle ground between those and the budget models like the BTwin E50, which costs just £899.99. It's looking, therefore, to add a sizeable jump in quality.

To that end, Dahon has tried to pack it with premium features for a cut price. This is done largely through producing the vast majority of its aluminium parts and components in-house, only looking elsewhere for the YBN chain and Sunrace cassette.

Dahon Unio E20 features and ride feel

As an experienced folding bike manufacturer, it comes as no surprise that the Unio E20 is a perfectly capable ride without the electric assist.

It was actually originally named the E9 for it's nine gears, and that's a standout feature. The unusually wide spread of gears means the Unio E20 is capable across a variety of terrain with or without the electric assist.

Those gears are controlled by trigger shifters under the right handlebar grip and are easy to actuate without moving your hands.

The bike's comparatively light weight facilitates its capability further. Hitting the scales at 16.1kg, it isn't objectively light, especially if you do intend on carrying it for a large part of your journey, but it is lightweight for its price and spec.

Dahon has achieved this through its 'Dalloy' double-butted aluminium frame and fork that the brand claims is 20% stronger than 6061 aluminium. Double-butting means it's thicker where the frame needs to be stronger and thinner elsewhere to save weight.

The Unio E20 also uses Dahon's Sonus tubing – a tall profile with a wide but flat base – which Dahon says keeps strength and stiffness high and weight low.

Almost all of the bike's weight is in its rear half. The motor unit is situated at the bottom bracket junction with the cranks mounted directly to it while the battery is hidden in the seatpost, which gives it an oversized appearance.

Aesthetically that works in its favour as it doesn't stand out when the bike's being ridden, and a lot of the bulk is disguised when the bike isfolded – it's a neat design.

With so much weight towards the back of the bike the steering feels light and reactive. This is useful for technical inner city riding on busy roads but does take some getting used to, and can feel a little unstable at high speeds, whether that be down hills or just with the speed from the electric assist.

Dahon Unio E20 electric assist

Powering the Unio E20 is the brand's own 36V 200W motor. There are five levels of assist that can be controlled via a small screen on the left side of the handlebars, which also shows battery levels and speed.

In the highest mode the motor packs some punch, with strong accelerations that make getting away from traffic and getting up short hills easy. Bear in mind though that the 200W power (less than the most powerful street-legal e-bikes) means that climbing speed won't reach the 15mph offered on the flat.

I would be inclined to suggest the motor's five levels of assistance is a bit excessive.

A more streamlined three-step system (full-power, a middle assistance 'eco' mode and off) would be more user-friendly, because I rarely needed to finesse the exact amount of assistance required to the extent on offer. Feel-based fine tuning can be done through the gears.

Dahon Unio E20 range and battery life

The Unio E20 has a respectable claimed 60km range in its max assist mode – almost double the BTwin but approximately 20km less than the GoCycle – meaning it could get most people through a week of commuting between charges.

Charging is straightforward via a standard wall plug, with the supplied lead plugging into the front of the seatpost battery. The seatpost can also be removed fully if it's more convenient, for example if you don't have power where your bike is stored.

Dahon says it takes seven hours to get back to full power, so a short burst at the last minute won't do much good.

You can monitor the battery's level on the screen and the first bar will blink when it has under 10% remaining. However the indicator shows projected life rather than current levels, so will shoot down when going uphill and look full when descending, making it pretty unhelpful if you're riding through a hilly area.

Dahon says this issue isn't as noticeable when the battery is fully charged and the displayed power when riding on the flat is the most accurate representation of remaining capacity.

The brand also claims the battery will maintain its full function for 500 charges before it begins to decline, which is nearly ten years of weekly charges, by which point you might be in the market for a new bike anyway.

Dahon Unio E20 folding

Dahon says the Unio E20 should be straightforward to fold. Small latches free each section one by one and magnets on each wheel hold it in place once the process is complete.

Initially I found the final step to be confusing and struggled to get it to fit exactly right, meaning the magnets weren't close enough to each other to connect.

Dahon's accompanying instructional video is helpful though. I was able to deduce that the issue was likely due to 'mechanical adjustments' made in transit by an Unnamed Parcel Service.

When folded properly the Unio E20 gets down to 69cm×38cm×75cm, which is bigger than a Brompton Electric – and that doesn't include an extra bag to carry it, as supplied with the Brompton – but similar to other popular electric folding bikes like the GoCycle G4i's 61cm×37cm×88cm.

There isn't a handle or an obvious place to hold it when folded, though, making it tricky if you want to take it on public transport.

Dahon Unio E20: Verdict

On the whole the big advantage of the Dahon Unio E20 is its value. By producing so much of the bike in-house, Dahon has ensured it does pretty much everything that you'd expect from an electric folding bike at a good price.

It's light enough, rides well with power on or off, has a strong assist and a good battery life.

The only thing it's missing is lights, which for a bike that'll probably be used for commuting and already has a power source is a bit of a miss. Cheaper options like the BTwin 500E come with battery-powered front and rear lights as standard.

That being said, the money you'd save in choosing this over, say, a Brompton, you'd have more than enough left over to adequately illuminate the Dahon Unio E20.

€1,875 (approx £1,570)