Sinclair A-Bike versus Mobiky Genius
FIRST PUBLISHED 2006

For decades, engineers have poured time, effort and money (usually other people’s) into designing a better folding bike. The Brompton broke radically new ground in the early 1990s by combining excellent rideability with a compact package, and this combination has remained the gold standard ever since. Just for the record, a Brompton can be ridden more than 50 miles in a day, and fold as small as three cubic feet, or 90 litres for Euro-people. It weighs 9.7 – 12.5kg, according to model.

Unbeatable? Well, yes and no. The Brompton is relatively heavy, and – as these micro-folder manufacturers are quick to point out – we don’t all need to ride 50 miles in a day. Most commuter rides are a couple of miles,and some even less. Surely,a lighter, simpler, more compact machine would suit many users?

Quite by chance, two have arrived at once: the Mobiky Genius is designed in France and manufactured in the Far East. From London (but manufactured in Malaysia) we have an advance sample of Sir Clive Sinclair’s long awaited A-bike.

Design

Both of these machines look like stylish, sophisticated urban transport tools, and for some people, that’s more than enough, whether they work or not. The A-bike, in particular, is cheap (£199) and sufficiently compact to be artfully posed as a loft-living object d’art. As a folded package it’s as neat and homogeneous as a folded Brompton. Unfolded, it’s rather less successful, appearing somewhat spindly and frail. It also looks like a bike without any wheels, because where you expect to see wheels, there are two six- inch rubber diskettes. Yup, those are your wheels.

The Genius is rather less satisfactory folded.The bits don’t come together so neatly, and it produces a big untidy package, but unfold it and you’ve got a relatively normal bicycle with a 97cm wheelbase, sitting on (relatively) conventional 12½” wheels.

Both bikes get around the small- wheel gearing problem with double reduction drives to spin the tiny wheels at a reasonable rate. The Genius uses a 3-speed hub and conventional chain and sprockets, which look rather over-engineered in this application. It’s hard to understand why they bothered, because a 54- tooth chain ring and 13-tooth sprocket would have achieved the same thing for a lot less weight and cost, without increasing the size of the folded bike (although it would have needed a chain tensioner when folded).

The first chainset gives a reduction of 2.36:1 and the second 1.75:1. With 12½” tyres (more like 12″ in reality), and the Sturmey Archer hub, the gears come out at 37″,50″ and 66″ – a bit on the low side, but more or less conventional. Anyone wanting higher gears can simply change the final 16-tooth sprocket for something smaller.

The A-bike is altogether more sophisticated. The primary reduction is by conventional chain (oddly 1/8″ width rather than the narrower 3/32″), but the secondary reduction uses a dinky micro-pitch chain, making the drive lighter and more compact. The result of all this technology is a whacking 6.8:1 gear reduction, and a single 41-inch gear. This is painfully low, but a necessary compromise. Sprocket sizes are 14-tooth and 8-tooth on the primary drive, and 35-tooth and 9-tooth on the secondary. An A-bike ridden predominantly on the flat could certainly pull a higher gear, but space is tight, so there’s little or nothing that can be done to change the ratio. The wheels, layshaft and bottom bracket use ball bearings throughout, but the bearings are a fairly loose push-fit in plastic housings which twist under load. Time will tell whether this light, simple system survives.

A-bike and Genius on the Road

The Genius is a pleasant surprise. The concertina folding design opens out into a long, low and rather comfortable bike. The 12½” tyres work surprisingly well, despite a lowly pressure rating of 35psi. These tyres are still rare,but there’s no doubt this size has a future. The Genius’ Cheng Shin tyres are a chunky 2¼” wide, giving a supple ride with reasonable rolling resistance. We managed a roll-down speed of 11.6mph on our test hill, which is the sort of result we might have expected from a 16-inch bike a decade or so ago.

The gears feel ‘grown up’, despite the lowish range, and well up to a modest commute. We rode our 10-mile commuter test course in 45 minutes, which is only a few minutes off the ‘big folder’ pace. The frame is wonderfully rigid, thanks to some seriously over-engineered bits and pieces and ball bearings, no less, in the frame joints. There has to be a penalty, and in this case it’s a bike weighing 14.1kg – one of the heaviest folders we’ve ever tried. No, you wouldn’t want to carry it far, but under duress we would be willing to ride the Genius for 15 or 20 miles.

So much for 12½” tyres! The A bike has 6-inch tyre s,and it’s hard to understand why designer Alex Kalogroulis chose this size over say, 8-inch. Slightly larger wheels would have added very little to weight and folded size, but improved the ride quality no end.

Well, it’s clearly not going to be well placed in the Tour de France, but is the A-bike up to a daily commute? To find out, we did quite a bit of fettling to get the thing rolling properly. To be fair, our bike is a pre-production prototype, but it arrived with a number of high-friction faults; rubbing brakes (of which more later), a tight, dry chain and squidgy tyres. The tyres are rated at 90psi, and you need every pound in the rear, if not the front. Connecting a track pump nozzle to the constricted Schrader valves is difficult, but when you do, 90psi comes up in three full strokes. Very useful, but if you pause for a microsecond in disconnecting the pump, most of it comes out again. Incidentally, these tiny tyres have conventional tubes, so the puncture repair procedure should be familiar.

Wheel removal is easy at the front, but at the back you can get in quite a tangle with the brake band and chain. Adjusting the secondary chain means removing the front wheel, reaching in, removing eight allen screws and rotating the bearing housings. As there are only three tension options, you may find – as we did – that the choice is between overtight causing too much friction, or over-loose, allowing the chain to jump under load. Even getting at the (non-adjustable) primary chain and freewheel means splitting the chain case, which essentially involves dismantling the whole bike. Clearly chain adjustment is a long-winded and tedious job.

Unlike the Genius, the A-bike is a seriously lightweight machine, weighing just 5.7kg, exactly as claimed. To achieve this headline figure, they’ve used some clever materials in clever ways, but the bottom line is a rather wobbly frame. There’s an 85kg weight limit, but even those safely below this will feel the frame flex as they climb aboard. Press on the pedals and the bottom bracket twists and squirms. You get used to this, but the flexy frame and stictiony headset bearings tend to result in a wobbly ride at first. With a 74cm wheelbase, and the saddle over the back wheel, the only safe riding position is to sit right on the nose, leaning well forward. Relax and you’ll be off the back before you’ve realised what’s happening.

Once under way and up to cruising speed, the ride is quite good if you avoid potholes and rough, broken surfaces. The official line from the manufacturers is that cyclists instinctively avoid potholes anyway. This is true, but if you are faced with a kerb, a pothole and two white vans passing at 60mph, you’ll probably go for the pothole. That’s unpleasant on a conventional bike, and survivable on a 16-inch folder, but with 6-inch wheels, it isn’t an option. Consequently, you have to watch the road with particular care and keep escape routes in mind.

If you can find a decent surface, the 6-inch wheels do surprisingly well, although the bike stopped some way short on our test hill, despite all the fiddling to make it roll better. You don’t notice too much on the road though. A bigger problem is friction in the crude plastic headset bushes. Small wheels need to make rapid changes of direction, and friction in the steering doesn’t help. After a few miles, the grumbles became aches and pains caused by the peculiar geometry of the triangular frame. With a maximum saddle height of 92cm, a high bottom bracket, and 140mm cranks, you’d need the legs of a leprechaun to find a comfortable straight-leg riding position.

Ah yes, the saddle. The problem here is that it’s shaped for folding rather than riding, with a big cut out at the back and a rather high and solid nose. If you have a bottom this shape, you’ll be a medical curiosity, and we couldn’t find anyone willing to sit on it for very long. The need to sit well forward tends to put you on the nose of the saddle, throwing a lot of weight onto the handlebars, straining the lower arms and putting a bit of a kink in the neck. If you suffer on a normal bike, you are unlikely to be comfortable on this one.

So how far did we ride? Showing true grit and determination, we completed our 10-mile commuter run in a slow, but by no means disastrous 66 minutes – an average of 9mph. With a 40″ gear, it’s hardly surprising that the A-bike managed to climb all the modest (sub 10%) hills on our circuit, but despite all the wobbles, it was surprisingly easy to ride out of the saddle. This brought the bonus of blessed relief from riding in the saddle. Record-breaking runs aside, we think the practical range for a nicely run-in example with well-inflated tyres, would be about two miles. Top speed? If you need to ask, sir, you’re buying the wrong bike. Cruising speed is in the 8-10mph zone (making our 9mph, 10-mile ride quite good going), but with some super cadence and great concentration, we managed to accelerate the A-bike to 15mph on the flat.This takes nerves of steel, a good surface and strong legs. The rear tyre gets quite warm after a few miles, which shows where much of your effort is going. But to be fair, small tyres show the heat more than big ones.

Cornering on the Sinclair has to be a measured affair. Unless you sit well forward there’s little weight on the front tyre 66 minutes – an average of 9mph. With a 40″ gear, it’s hardly surprising that the A-bike managed to climb all the modest (sub 10%) hills on our circuit, but despite all the wobbles, it was surprisingly easy to ride out of the saddle. This brought the bonus of blessed relief from riding in the saddle. Record-breaking runs aside, we think the practical range for a nicely run-in example with well-inflated tyres, would be about two miles. Top speed? If you need to ask, sir, you’re buying the wrong bike. Cruising speed is in the 8-10mph zone (making our 9mph, 10-mile ride quite good going), but with some super cadence and great concentration, we managed to accelerate the A-bike to 15mph on the flat. This takes nerves of steel, a good surface and strong legs. The rear tyre gets quite warm after a few miles, which shows where much of your effort is going.But to be fair, small tyres show the heat more than big ones.

Equipment

Brakes on micro-bikes tend to be poor, and this pair are very typical. The Genius has a classic Chinese combination of band brake at the rear and cable operated disc at the front. They are appalling. The rear band brake has a convoluted cable run and can just about manage 0.3G going forward, which is enough to lock the wheel in dry conditions. In reverse (holding the bike on a hill, for example) the braking force more or less evaporates, and in the wet (reproduced this hot, dry summer with a watering can), the force is about halved. None of this would matter too much if the stylish front disc brake was any good, but it’s a wonderful example of style over substance. To stop the brake binding you need to slacken the adjuster until the pads hardly bite. Testing the brakes thus with our handy G-meter the bike ran off the end of the car park, depositing the tester in a patch of nettles. Reset with binding brakes, we managed a pathetic best stop of 0.25G, which is positively dangerous for a front brake. The only good news is that things don’t get much worse in the wet, so once you’ve acclimatised, there should be no nasty surprises in store.

By contrast, the A-bike’s little band brakes work quite well. Both suffered from binding bands initially, but once properly set, worked well. Best stop from the front is a passable 0.45G, and from the back, 0.3G, which is just enough to lock the wheel. As with the rear band on the Genius, the effectiveness is more or less halved in the wet. The open design means that water is more likely to get in, but on the other hand it’s more likely to dry out too. Shielded band brakes can stay moist and unpredictable for days. The A-bike gets a very cautious thumbs up in the braking department, but neither bike would be up to the cut and thrust of city traffic on a damp February morning. Both bikes have mudguards, but they’re too short to keep you dry, especially the vestigial ‘dodo wings’ on the Sinclair. And we all know what happened to the dodo. The Sinclair does at least have enclosed chains, but there’s a big gap underneath and the chains share the enclosure with the rear tyre, so it’s guaranteed to fill with salt and grit in the wet. Carry-bags are standard accessories with both bikes. The A-bike pops into a neat shoulder bag, with a smaller compartment for carrying tiny luggage, which looks useful. The Genius bag is huge, but with no shoulder strap you’re supposed to lift the 14.1kg bike with two straps on the top of a tall bag. Smaller folk will find this impossible.

Folding

Both bikes score very highly here. The A-bike looks tricky, but it’s a logical process and if you get stuck there’s an excellent manual written by someone whose first language appears to be English. You start by pressing a button on the ‘crosspiece’, which hinges upwards, bringing the wheels together, where they clip neatly in place. Then the handlebars rotates through 180 degrees, leaving the bars facing backwards ,and you whip off a pair of quick releases and press four buttons (easier than it sounds) allowing the frame tubes to telescope downwards. As the tubes drop,the saddle stem automatically folds down and clips into place. Apart from the folding pedals and hinging down the handlebars, neither of which are essential, that’s about it.

For the novice, the operation takes about 20 seconds, but we saw an experienced member of the A-bike crew fold the bike in seven seconds. Unfolding will be a little slower because of the need to tighten the two frame quick-releases (the saddle height should not need adjustment). Incidentally, if you forget, the bike is still rideable, which may turn out to be a problem in practice, but then it may not. It all depends how stupid the Great British Public turn out to be.

We made the folded size a little more than the manufacturers’ claim: 67cm tall, 33cm deep and 17cm wide, but that still gives an incredible folded volume of 37.6 litres or 1.33 cubic feet. Sinclair claims that the folded A-bike is a third the size of the Brompton, and that’s more or less true. And carrying that 5.7kg (12 1 / 2 lb) package will be easy over modest distances.

If anything, the Genius is even easier to fold. The scissor-style frame is held in either the up or down position by a single metal rod resting on the rear frame. When you’re riding, this takes your weight. Lift the bike by its central carry-handle and the rod prevents the frame closing up until it’s pushed towards the chunky saddle stem. With the rod out of engagement, a lift on the handle brings the frame and wheels together. Finally, a quick-release lowers the saddle,and you lift a pair of buttons like trumpet valves to fold the bars down. Time is broadly similar to the A-bike,but at 14.1kg (31lb) the resulting lump is very nearly three times the weight.

Once folded, the Genius can be wheeled around in collapsed form, which is useful at a busy station for example – but sooner or later you will have to lift it, and many people would be unable to lift this bike into a car boot.

Conclusion

The micro folder is an intriguing concept. There are many occasions where a Brompton or Dahon is too darn big for the job, and these clever designs promise to fill the gap between micro-scooter and grown-up folding bike.

Do they succeed? Not very well. Despite their undoubted attributes, both these bikes come unstuck for different reasons. The Genius can tackle longish rides and modest hills almost like a ‘proper’ folder, but when folded it’s significantly bigger, heavier and clumsier than a Brompton. You could forgive this if it was half the price, but at £499 it’s well into Brompton territory.

The £199 A-bike is a bit more realistic, but the performance is closer to the microscooter end of the market. On paper, the A-bike seems to fill that scooter/bike gap very well, but the practical range of a mile or two is not a great deal more than a lighter, cheaper and more compact micro-scooter can achieve. If your trip to the tube station is right on that limit, you may well disagree – the Sinclair certainly does have an application, but we think it might be rather narrowly defined.

Would we buy either bike? No. The Genius is too heavy and with the A-bike it comes down to safety. We do sometimes ride a micro-scooter to our local station. It won’t even look at potholes or rough surfaces, but it nips along the pavement reasonably well, jumps over obstacles and folds to nothing on the train. The A-bike has to share the road with 40-tonners, mad phone-wielding reps, killer potholes and all the other unpleasantnesses of modern travel. We’re comfortable with 4-inch wheels on the pavement, but very nervous about 6-inch wheels on the road. The A-bike is oddly reminiscent of the C5 – a superb idea, quite well executed, but impractical in the real world.

Update: The A-Bike City (£299.99) with 8-inch wheels was introduced in 2010, but we don’t expect this to significantly improve the overall performance.

Folding Bike Specifications

	Sinclair A-Bike	Mobiky Genius
Price	£199	£499
Weight	5.7kg (12½ lbs)	14.1kg (31 lbs)
Gears	Single Speed. Ratio 40″	3-speed Sturmey Archer. Ratios 37″, 50″, 66″
Folded Size	H67cm L33cm W17cm	H78cm L67cm W30cm
Folded Volume	37.6 ltr (1.33 cu ft)	156.8 ltr (5.5 cu ft)
Wheelbase	74cm	97cm
Coasting Speed	Failed	11.6mph
10-mile Circuit	66 mins	45 mins
Manufacturer	Daka	Mobiky
UK Distributor	Mayhem	Magic Bikes

A to B 55 – August 2006