“..The A-bike will be artfully posed as a loft-living object d’art...”

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 microfolder 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 sixinch 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 12 1 / 2 " wheels. Both bikes get around the smallwheel 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 54tooth chain ring and 13tooth 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 12 1 / 2 " tyres (more like 12" in

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“Genius: a pleasant surprise... we rode our ten mile commuter course in 45 minutes...”

reality),and the SturmeyArcher 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.

On the Road The Genius is a pleasant surprise.The concertina folding design opens out into a long,low and rather comfortable bike. The 12 1 / 2 " 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

LEFT The A-bike has a double chain reduction driv e.The primary chain is conventional,but the secondar yuses a micro-pitch chain.Note the quality bearings and the rather frail casing BELOWThe tiny drive sprocket in the rear wheel.Note the reflector and rather awkward valv e

Genius’ Cheng Shin tyres are a chunky 2 1 / 4 " 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

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