ORIGINAL ARTICLE FROM JUNE 2005. The Roo EL went out of production some years ago. Dahon has since tried other variants based on different power systems and bikes, but none has been very successful

Folding electric bicycles are not everyone’s cup of tea, but where other crystal balls reveal recumbent bicycles, or perhaps four-wheel-drives, according to taste, our future scenario includes neatly folded electric bikes, speeding to the hilly suburbs on fast silent electric trains (this isn’t the UK, obviously), and hordes of smiling commuters whining gently home. A light, power-assisted folding bike would certainly widen the appeal of alternative transport.

…is the Sparc good enough to snatch the development lead?

The problem is that the current machines are either big and heavy or small and feeble. If they’re heavy (believe us, we’ve been there) they will never get folded, and if they’re too weak, you might just as well ride a conventional bicycle.There are numerous heavyweights around, but only two serious lightweight contenders: the Panasonic WiLL tested in A to B 46, and the Dahon Roo EL tested in A to B 29. At 17.3kg, the Panasonic was marginally the lightest, and marginally the cheapest (if that isn’t a contradiction with something costing £1,200).At the time, it offered the greatest range: a paltry 10.8 miles. The Roo managed only 9.9 miles then, but its Sparc motor has been upgraded and improved for 2005 – is it good enough to snatch the development lead?

On the Road

Back in April 2002, we tried the original Roo EL, fitted with the then new, and terribly clever SRAM Sparc hub, providing five conventional gears and electric-assist, in one relatively compact package. It looked very shiny and high-tech, but our excitement was tempered by the sad little lead-acid battery and twin motors that sounded to be (and indeed were) borrowed from electric drill technology.

Top assisted speed was 14mph in theory, but the weak motors meant pathetic hill-climbing and assistance that more or less dissolved above 10mph, giving a lethargic average speed of 10.8mph. Range, from the tiddly battery, was just ten miles. In other words, you really were better off with a conventional Dahon and the near-thousand pound surplus in the bank, earning lovely interest.

Superficially, little has changed on the 2005 model, but the battery has been upgraded to NiMH (already yesterday’s technology in China) and the motors and electronics have been revised to give a bit more poke – in other words, the very changes we suggested three years ago.

First to the battery.This is the same physical size, sitting unobtrusively on the front of the rack like its predecessor, but it’s a little lighter at 2.8kg, against 3kg for last season’s model.That ought to make the machine a couple of hundred grams lighter, but extra equipment means the package now weighs 200g more than before, at 18.1kg.

…those with weak legs and/or mountains to climb should look elsewhere…

The good news (there had to be some) is that this slightly heavier EL goes faster, and much, much further.The new battery has a capacity of 134Wh, some 60% more than its predecessor, but the new technology and improved gearing have helped to double the range to 20 miles.

Under power, the Sparc produces a gentle whine that’s odd enough to attract some attention, but it’s quieter than before.The system works by sensing pedal movement, and squirting a bit of assistance into the hub until either (a) you stop pedalling, or (b) road speed exceeds 14mph.The disadvantage is that the pedals need to turn a bit before the motor cuts in, but thereafter, you’re very much in control.You have to keep turning the pedals, but you don’t have to do any work, because the machine is sensing pedal movement, not your power output. Peak power is up from 120 watts to 170, and the Sparc now maintains that output over a broader range of speed. At a walking pace, it still feels a bit weak, but above 10mph the turbo cuts in and it gets quite chirpy, before fading away from 13mph, and cutting abruptly at 14mph.That might sound a bit disappointing, but in practice, this very limited degree of assistance has been carefully targeted. Provided the hills aren’t too steep, the Roo nips along well, the motors waiting in reserve until speed drops below 14mph, then cutting in to give gentle, steady assistance. Unfortunately, the motors are linked to wheel speed rather than pedal speed, so when you reach a proper hill and begin to change down through the gears, they run slower and less efficiently.The steeper the hill, the worse the effect.

Hills of about 10% are dispatched easily enough, and we chugged gently up a gradient of 17%, thanks in part to the Roo’s low 32″ bottom gear. But those with weak legs and/or mountains to climb should really look elsewhere. If you don’t put any effort in at all, the little motors do a manful job on the flat, but the poor low speed performance limits the maximum gradient to about 5% (1 in 20).

There’s an Eco setting too. Back in 2002, we dismissed this as a complete waste of space, but it actually feels as if it’s doing something now, offering 170 watts at low speed, the power falling gently to cut out at 10mph.

Weight versus range.The 2005 Roo EL is the first folding electric bike to become firmly viable. Nothing comes close for now, but weight of 13kg and a 20 mile range are already practicable.

The fuel gauge is a 3-LED array on the handlebars, which rather depressingly loses one light at 2.8 miles, two at 7 miles, and the whole lot at 11.8 miles. But there’s actually another eight miles in reserve, because the Roo EL presses on to about 17 miles, then increasingly slowly to a final range of 20 miles at an average of 12.3mph. Not exactly a thrill a minute, but most people could lift the EL off a train or out of a car boot, unfold it and ride 20 miles into the hills at a good pace. OK, that average speed is nearly 1mph slower than the Giant Lafree, but the Roo EL is the first bike to narrowly beat the Giant’s 6.8Watt/hour per mile fuel economy record, taking the honours with 6.7Wh per mile.That’s around 1,500mpg, so you needn’t be too concerned that the Roo EL is guzzling up the world’s energy resources.

None of this sounds very exciting, but it’s a breakthrough of sorts. Dahon, incidentally, claims a range of 31 miles, which is achievable, but only with very limited use of the power-assist.

By our reckoning, the claimed 3 hour 40 minute charge time is a bit optimistic. Our battery took 4 hours 20 minutes to reach an 85% charge, before topping up at a lower rate for another couple of hours, and a trickle charge thereafter.With this gentle, three- stage charge, and a motor that’s relatively kind, we would expect the battery to have a good long life.

…At 18.1kg, it shouldn’t give you a hernia, provided you don’t carry it too far…

If you run the battery down, or just feel like doing all the work, pedal gearing is slightly higher – a more practical 32″ to 81″.This small change makes a big difference in terms of rideability, and that’s the magic of a bike like this – the electric bits add no friction and very little extra weight, so it can be pedalled just like any other 20- inch Dahon. The sporty- looking Schwalbe Marathon 15 Slicks proved slightly disappointing in terms of rolling resistance, achieving only 13.7mph on our test hill.Yes, that’s right, they’re slower than Schwalbe’s chunky puncture-proof jobs on page 24). Quite why, we have no idea.

 

Folding

This is essentially a standard Dahon folding bike.The handlebars drop down, and the frame folds midway along, sandwiching the bars between the two frame halves. Like most 20-inch Dahons, the Roo come with a little magnet and plate to hold the folded bike together, but in our experience, it’s only possible to get the plates to touch by leaving the handlebars up. On the EL, the width problem is compounded by the large Sparc control switch, which fouls the frame. Dahon claims folded dimensions of 81cm long, which we’d agree with, 56cm tall, which can only be done by removing the seat pillar, and 28cm in width, which is a ridiculous claim, or at least, we’d like to see how they do it, because we can’t.These dimensions would give a folded volume of 127 litres or 4.5cu ft, which just isn’t attainable.

 

More realistically, we made a package of 80cm in length, 65.5cm in height and no less than 40cm wide: 210 litres, or 7.5cu ft. That’s still the most compact folding electric bike we’ve seen, and smaller than average in non-assisted folding bike terms.The Roo EL is heavier than a conventional bike, but at 18.1kg (40lb) it shouldn’t give you a hernia, provided you don’t carry it too far.

Equipment

Well, of course, you get those five quality German hub gears.The SRAM hub has a rather slow and ponderous change compared to its Sturmey Archer rival, but it’s quiet, reliable and never seems to miss a gear.

Elsewhere, the Roo is well-equipped.The powerful V-brakes are worked by low- friction Jagwire cables, there’s a solid-looking alloy centre stand,Tranz X suspension seat post, a decent rack, mudguards, and a neat smoked-plastic chainguard.The Roo also comes with an unbranded, but effective LED rear light, but oddly, no light at the front.

Height adjustment is reasonable, the saddle going up to 104cm (previously 102cm), and the handlebars adjustable from 95-110cm.When we tried the bike in 2002, the bars were of the briefly fashionable non-adjustable kind, but Dahon has presumably been swayed by customer reaction and put the telescopic bit back in.We’d say that height- adjustable bars just aren’t worth the weight and complication.

Conclusion

At £1199, the Dahon Roo EL is expensive – hardly surprising when the components start life in Germany and China, then travelled via Taiwan to the UK, where a distributor adds a margin, and a UK agent adds another. In the States, you can pick one up for the equivalent of £700, and in the UK and Europe they are sometimes discounted to £1,000 or less, so it’s worth shopping around.

Price aside, the Roo EL has developed into a great little bike. And as the chart on page 18 demonstrates, it has moved overnight from the bottom of the league table to the top. It’s the second lightest machine on the market and – now that the Brompton/Zap has been withdrawn – it offers the best range too.

Specification – Dahon Roo EL

Dahon Roo EL £1,199. Weight bike 15.3kg battery 2.8kg total 18.1kg (40lb) . Gears SRAM Sparc Gear ratios 32″ 40″ 51″ 66″ 81″ . Battery NiMH . Capacity 134Wh . Range 20 miles85% charge 4hrs 20 mins . Spare battery £125 . Running costs 7.8p/mile . Fuel consumption battery only 6.7Wh/mile battery & charger 10.9Wh/mile . UK distributor Fisher Outdoor Leisure tel 0208 805 3088 mail sales@fisheroutdoor.co.uk

Thanks to Electric Bikes Direct for loan of the test bike: www.electricbikesdirect.co.uk

 A to B 48 – Jun 2005