Most of the serious folding bike designs have gone out of production at some point: Brompton, Micro, Strida, Microbike, and so on, but the majority have subsequently returned. Some, like Peter Radnall’s little Micro, have performed the feat twice, but all – with the exception of the Swedish (then Japanese) Microbike – remain in production at the time of writing.

Until late September, the Airframe seemed to be the exception. Conceived by Wimbledon architect Grahame Herbert in 1978, the Airframe went into limited production a few years later, but just about everything went wrong, and the project rapidly foundered.

For 15 years, this unusual bike was largely forgotten, but our story in 1996 (see Folder 19 & 20) helped to rekindle an interest, and Grahame went on to re-design the machine, eventually finding an engineering company with the will and the know-how to produce it. Now, after a further six years, a small production run has commenced.

A great deal has changed in a quarter of a century. On the positive side, production techniques have improved, making this innovative but complex light alloy machine more practical. On the other hand, the folding bike market has come a long way too…The commuter side of things is now dominated by the Brompton, and the Brentford company will take a lot of shifting from that top slot. In the 20-inch market, Dahon’s machines look conventional, but they’re lighter, faster and cheaper in relative terms than their 1980s equivalents. Competition is even fiercer at the sporty end, with Bike Friday, Birdy, Airnimal and others fighting for sales. In short, the market that was new and exciting in the early 1980s is much more sophisticated, and any newcomers or returnees will have to fight hard to survive. Does the Airframe have what it takes?

Airframe

The Airframe is quite unlike any other bicycle, owing more to structural engineering than transport machinery, which is what one might expect from an architect designer. The best way to visualise the frame is as a group of three triangles, with the usual cycle paraphernalia – wheels, cranks and chains – bolted to the extremities.The triangles look similar to a traditional diamond frame, but the principle is completely different, because almost every joint is hinged, enabling the triangles to fold into long thin triangles when the seat tube is lifted up. In use, the rider’s weight passes down through the seat-tube, transferring the load into the two top tubes, which try to make the wheels do the splits.They can’t, because the bottom tubes are in tension, holding the wheelbase and bracing the bottom bracket. In theory, the more weight applied at the top; the more the bike tries to do the splits; the more tension in the bottom tubes; and the more rigid the machine becomes.

Conventional aluminium frames can end up surprisingly heavy because aluminium – although light – is liable to flex and fail unless produced in thick (ie rigid) sections. In a conventional frame, there’s lots of stress around the frame joints, made worse because they’re usually welded. On the Airframe, flexible joints are able to ‘give’, so bending and twisting doesn’t really occur in the tubes, and there are few stress-raising welds. Consequently, the bike is constructed of very light tubing.

All dastardly clever, but don’t expect a bicycle that’s rigid in the traditional sense.You don’t so much ride an Airframe over the landscape, as ooze through it, gently rolling with the lumps and bumps rather than fighting against them.You might not fancy a bike that goes with the flow, particularly if you have memories of the Bickerton, but the result is a surprisingly sporty beast that rides as well as some suspended machines. Clearly an element of ‘give’ brings compensations.

…the gears are a bit disappointing for such a sporty machine…

Riding

The first, and rather unnerving, impression is that the pedals are loose in the cranks. Once you’ve got off and ascertained that they aren’t, it begins to dawn that that gentle creak was the crank assembly moving, and far from being a problem, it’s all part of the fun.

Now, as any frame builder will tell you, these sort of movements are not conducive to efficient power transmission, but the Airframe certainly feels efficient, climbing hills at least as well as the Brompton, even with the rider standing out of the saddle. All very strange, particularly as the bars are pretty flexible too.The handlebar stem, by the way, appears to harbour one of the few places where twisting forces might cause problems – we’d guess the kink just above the headset was the weakest point.

Get over the wayward bottom bracket and unexpectedly good hill-climbing, and sooner or later you’ll hit a nasty bump.Those used to small-wheeled bikes with high pressure tyres (100psi Schwalbe Marathons in this case) will know exactly what to expect, but the Airframe is different. Even at maximum tyre pressure, you can hit an unexpected 4cm kerb at speed and live to tell the tale.With a little less pressure in the tyres, the bike simply floats over obstacles, dissipating the shock. Less serious road furniture such as gratings and man-hole covers disappear completely.

We’ve criticised suspension in the past for being too hard, too soft, or – most annoyingly of all – under-damped.The Airframe does very well without any suspension… The downside is unwelcome lateral twisting and bending in the frame joints. It is possible to ride an Airframe fast and point it with a surprising degree of precision down switchback roads, but this sort of entertainment is not for the faint-hearted.

The gears are a bit disappointing for such a sporty machine, but we’re glad Airframe opted for hub gearing.There are few suitable hubs around at the moment, so the company has made do with the Nexus 4- speed.This unit can run with silky smoothness, but it’s hard to adjust, relatively inefficient and lacking in gear range. Our pre-production bike (by no means the final spec, incidentally) offered gears of 43″ (on the high side), 53″, 64″ and 78″ (on the low side).That 184% range is similar to the 3- speed Brompton, but rather less than the 215% offered by the Brompton 6-speed. Ironically, that bike’s close ratio hub/derailleur system might have suited the Airframe better than the Brompton, but there we are.

Tyres are Schwalbe Marathons – not as fast as the Brompton tyre (a slightly disappointing 14mph on our test-hill), but safe, comfortable and probably the best all-rounder.

The riding position is sportier than most folding bikes, with a saddle set well back and low bars. If you’re more used to a touring bike, and have rejected the Brompton for its upright stance, this will be more to your liking. For more services that will be more to your liking, visit https://myamericanmaid.com/. The saddle height is adjustable from a rather high 87cm to 101cm, but the bars are less helpful, moving only a couple of centimetres around the 95cm mark. You wouldn’t get a short person on our Airframe, while those in the six foot region found the saddle OK but the bars a bit low.

So much for sporting around on your lonesome. Like most folders, we’d guess the Airframe will spend much of its life in a commuter situation. For luggage carrying, you either fold the rear rack up against your briefcase and bungee it to the seat tube, or drop the briefcase in the carry-bag, clip the bag to the saddle rails, and tuck the rack up behind, with or without bungee according to taste.

It’s hard to resist making comparisons with the Brompton’s pricey, but super-duper commuter pannier system.The Airframe arrangements are nothing like as clever and nothing like as quick, but well up to commuting with a single small hard case and/or a bit of loose shopping on the way home – let’s say half a dozen oranges, a bottle of wine, two litres of milk, and a tin of dog food. Any more and the bag rolls and sways, catching your ankles and threatening to spill its precious cargo.

The bag isn’t very stylish either. In terms of street-cred (or 7.15-to-the-city-cred in commuter-terms) the Airframe looks super-sexy and the briefcase holder is stylish in a 007 sort of way, but the carry-bag has as much sex appeal as a deflated balloon.You’ll lovingly unfold the bike where everyone can see, march purposefully out of the station and fit the bag round the corner.

Let’s face it, the Airframe is not really a machine for carrying things on. It’s as sensuous, highly strung – and (arguably) as rewarding – as a racehorse.Without exception, the Airframe’s bright alloy tubing and CNC-machined pastel-anodised bits and pieces drew admiring glances and comments.The anodised bits come in pastel pink or blue – both very fetching, but watch what you wear or you’ll be upstaged by your wheels.

Folding

…we found it a more practical package than the Birdy, and easier to fold too…

Some would say this was the Airframe’s strongest suit… others would not know where to begin.The bike starts with an advantage over almost everything else on the market: it’s light – not spectacularly light, but comfortably lighter than most.The Airframe weighs 10.5kg (23.1lb) – against 11kg for a comparable Birdy, and 11.4 to 12.3kg for the Brompton. Only the Brilliant Micro can match the Airframe for weight, but that’s not really in the same performance league.

Weight isn’t everything of course. A folding bike needs to fold quickly, easily and – most important of all in the long run – repeatably. The weakness with the Airframe is that despite Teflon shims, the joints are pretty stiff, making folding a chore, and it never seems to produce the same package twice. It’s also one of those three-handed jobs.

First, twiddle the front wheel through 180 degrees until the cables start to complain, then push the bike backwards with the rear brake applied, whilst lifting the saddle. If all goes according to plan and you avoid catching a finger, the frame magically concertinas upwards.Assuming you’ve got this most difficult bit out of the way, you’ll be ready to rotate the safety catch, lift the locking plate and swing the handlebars down either side of the frame. Finally, and rather satisfyingly, you lift a sleeve, allowing the saddle stem to flop down against the package, then fold in the rear rack, which clips rather vaguely to the stem, holding everything together.

The Airframe also has folding pedals, but as conventional pedals barely protrude from the package, we wonder whether they’re worth all the trouble. Our pre-production bike came with Wellgo FP4s – possibly the worst folding pedal ever designed.We’d suggest specifying the excellent Next pedals on the production bikes.

If you’re intending to bag it up, folding can takes minutes rather than seconds, partly because you’re never quite sure how easily the bike will fit the bag. In practice, we found ourselves leaving the bag at home.The folded Airframe is long, but looks techy enough to earn the respect of most railway guards, although we wouldn’t venture onto a bus without the bag. Generally speaking, we found it a more practical package than the Birdy, and easier to fold too.

Folded volume is a very reasonable 180 litres, or 6.4 cubic feet in groats and spleens. Production bikes will be fitted with a quick release front wheel, reducing the length of the package to 92cm, and bringing the volume down to 162 litres. If you can live without a front mudguard, the volume comes down to 122 litres or 4.3 cubic feet, which is well into seriously compact territory. But removing wheels is a grubby, time-consuming task.Worth it, apparently, if you’re hoping to put an Airframe in the boot of the ‘new’ Mini.

…Chelsea or Cannes – anywhere style has greater significance than practicality…

Without bolting and unbolting things, you have a package that occupies about twice as much space as a Brompton, and a little more than the Birdy. In practical terms, it fits behind the seat backs on the train, or lengthways in a spacious luggage rack, but it won’t go sideways, and it won’t even think about fitting into one of those dinky little luggage shelves on the Class 158 or 159 (only provincial Brompton commuters will understand this one).

What you can do is place the bagged package on the overhead racks.We should qualify this, because racks vary in size, and many people simply can’t lift 10.5kg over their heads.Worth knowing though, especially if you can find a big strong man to do it for you.

Conclusion

With its dishy looks, comfy ride, and wayward behaviour, the Airframe is a bike you’ll either love or hate. Price-wise, it slots neatly between the pricier 6-speed Bromptons and the fairly basic Birdy Red. Its only real weakness in this company is the lack of gears, but that won’t be a problem if you’re commuting somewhere flat. In other words, it will go down a wow in Chelsea or Cannes – anywhere style has greater significance than practicality.

Will it succeed? The market is awash with folders at the moment, but there’s probably room for another bike as unusual as this one.The interesting question is who will buy it and why? Will women choose the Airframe for its light weight, sporty looks and colour co-ordinated bits? Or is this 20-something sporty male territory?

Specification

Airframe £650
Weight 10.5kg (23.1lb)
Folded Dimensions W32cm H55cm L103cm
Folded volume 181 ltrs (6.4 cu ft)
Dimensions (less front wheel) W32cm H55cm L92cm, (less front wheel and mudguard) W32cm H45cm L85cm
Gears Shimano Nexus 4-spd hub
Ratios 43″ 53″ 64″ 78″
Saddle height 87-102cm
Tyres Schwalbe Marathon 37 x349mm
Manufacturer Silkmead Tubular Ltd
tel 01582 609988
mail silkmead@btinternet.com