Wheel appeal

The folding bicycle is one of the toughest design exercises in the modern world, combining the efficiency of the traditional bicycle with a package that the rider can carry under his or her arm. Many handsome Cad sketches have been produced over the years, but very few have made it to the production stage.

Today’s most successful designs, while subject to constant revision, all date from a ‘golden age’ a quarter of a century ago, when British designers dominated the field. The Brompton, designed in the 1970s by west London engineer Andrew Ritchie, remains one of the best, and rides like a slightly twitchy version of a ‘normal’ bike, carries a similar luggage load and folds in several planes to produce a package little bigger than its 16-inch wheels. Ritchie claims to have given little thought to styling, but rigorous attention to engineering detail has honed the machine into a surprisingly elegant and practical form. ‘The curved main-tube was adopted mainly because it offered the most practical method of manufacture with a limited tooling budget,’ says Ritchie.

The Brompton’s only real weakness is weight (typically 12kg), but the company is working on this, and introduced a 9.7kg part-titanium machine in 2005, at a premium price of around £1000. ‘There is speculation that they will launch a full-titanium bike in future,’ says Andrea Casalotti of bicycle retailer Velorution.

Another celebrated model is the Strida, designed in the 1980s by Royal College of Art graduate Mark Sanders. Folding from a triangle into a long thin package, it is light (under 10kg) and folds very quickly. Sanders designed his machine to suit his own commute of a mile or so to the station, and the single-speed, lightweight nature of the bike reflects this. It has seen a great deal of development in recent years, emerging in ‘mk 3’ form as a surprisingly rideable machine, despite its strange geometry.

‘The message is getting through,’ says Sanders, ‘but acceptance is slow. Twenty years ago, the Strida was jeered at as weird. Now it’s generally regarded as cool.’

The biggest folding-bike manufacturer in the world, and one of the few brands not designed in the UK, is Dahon. The company is expanding rapidly, with sales growing at 30 per cent a year in the UK alone, according to agent Mark Bickerton.

US aeronautical engineer David Hon perfected the simple ‘fold-in-half’ mechanism in the 1980s, and this year Dahon launched its new lockjaw frame-hinge technology, used on the Cadenza bike, which makes the fold almost invisible. Also new is the Glide, with 24-inch wheels, which is bigger than most compact designs. The award-winning Ciao, launched last year, has a low, female-friendly step-through frame. With a clever mix-and-match of componentry, Hon has produced bikes weighing as little as 8kg, but there’s a price premium to be paid for this luxury.

Other folding bikes have come and gone over the years, but few have stayed long enough to make a serious impact. British ex-Formula One engineer Jon Whyte introduced the Mezzo in 2004. Boasting automatic self-locking catches, a hinge-free mainframe and ‹ aesthetically strong design, it’s a valid contender; but it is less practical than the leading models, and – in commuting terms, at least – practicality is everything.

In 2006, Sir Clive Sinclair finally launched his A-bike, with diminutive 6-inch wheels. Designed by Alex Kalogroulis, the A-bike hits the spot for weight (5.7kg) and folded volume (an astonishing 37l), but it’s a victim of Cad disease: it looks great on screen, and folds elegantly and compactly in practice, but it’s almost unrideable. It also looks oddly like a bike without wheels, and in a world where a man is still expected to arrive atop 27-inch wheels, 6-inch wheels can have a somewhat emasculating effect. Sales are not quite as predicted, an all-too-common story in the folding bike world.

Where to now? The brief is often interpreted as two-mile ‘home-to-station’ transport, but the Brompton and the larger Dahons can also be ridden 100km in a day. Most of the established names agree that weight is the key to the future, to aid portability. With space-age materials, 6kg seems achievable, but 7kg would still be way ahead of the game.

As for folded size, the Brompton’s 100l package tends to be treated as the industry gold standard. The Brompton and Strida have 16-inch wheels, and the general view is that smaller wheels need suspension, but suspension adds weight, and weight is a bigger drawback than size.

So, with little more than incremental improvements to designs first sketched out decades ago, has the industry stalled? Ritchie tentatively agrees. ‘There haven’t been any significant advances over the past 12 months,’ he says, ‘but anything could happen if someone’s imaginative enough.’

That innovation is already pouring off Dahon’s screens, claims Bickerton. ‘At Dahon we aim to improve our bikes by 15 per cent every year. We have more than 60 engineers working with the latest Cad software, and Dahon files more than 25 patents annually,’ he says. ‘That target puts a lot of pressure on us, but it means we’re always searching for ways to improve our bikes.’

Sales may be increasing, but folding models still account for a tiny proportion of bicycle sales. Sanders believes the lack of real design progress stems from a rejection of the concept by consumers. ‘Cycling has increased by 40 per cent in London, but nine out of ten of those new bikes are full-sized machines,’ he says. ‘As a designer, I am constantly mindful that I should be producing products that people want. But, what do they want?’ Unlike the ground-breaking Strida, Sanders’s latest folding creation, the Swivel-head, is designed to break down this conservatism, with big wheels and everyday styling. It is effectively a conventional bike, but the wheels come together, producing a large, but manoeuvrable package. ‘Coolness is linked to the herd mentality,’ says Sanders, ‘and especially in the UK, people don’t want to be seen as out of step.’

After years of striving to produce ever-smaller folding bikes, it seems the technology may well be about to flow the other way, exploring new and innovative ways of repackaging relatively normal, full-sized machines. Whatever the future holds, the folding bike remains a fascinating challenge.