Magnesium in frame to be cycling's metal of the future

THE SHED resembled an abattoir for bicycles. The rows of frames hung from the ceiling like carcasses on the way to the butcher.

These did not look like conventional bicycle frames. The shape was strange - an elongated version of the traditional triangle - and they had an odd, dull sheen. This was one of the first mass-produced batches of frames made from magnesium, a metal probably best known for its spectacular spitting in Bunsen burners during bored moments of chemistry lessons.

Magnesium may not seem the obvious material for bicycle manufacture, although engineers in the car and aircraft industries often use it for strong, flexible metal components.

Almost a decade ago Frank Kirk, an aeronautical engineer, had the bright idea that a magnesium bicycle frame could be made lighter and stronger than conventional aluminium or steel tube frames. He found he could make a magnesium frame only two-thirds the weight of an aluminium frame and one-fifth that of a frame made of steel.

The key difference between his frames and any other is that they are cast as a single component - from molten magnesium. This avoids the need for jointed tubes, which have to be welded for strength.

But the Chelmsford-based company he spawned, Kirk Precision, has been dogged by financial and technical problems. Mr Kirk approached two British companies in a vain attempt to raise finance. Things began to look up in 1989 when Norsk Hydro, one of the world's largest magnesium producers, bought his company. The Norwegians spent more than pounds 4m equipping the factory and the company hoped that production would start in March last year. In fact, the first bikes did not emerge until October and full production only started this summer. Without the backing of such a large company, Kirk Precision would probably not have survived.

Each frame is made from the magnesium extracted from one and a half cubic metres of sea water - just under 2.5kg (5.5lbs) of metal. This may seem hard to believe, but magnesium is one of nature's most abundant metals - a cubic metre of seawater contains 1.3kg (2.8lb) of magnesium. This magnesium is mixed with a little aluminium to give the frame a 'softer' feel and a tiny amount of zinc to help the metal flow more easily in the mould.

A Dutch team used prototype Kirk racing frames in its bikes for the 1990 Tour de France and one of Japan's leading cycling magazines voted the mountain bike its 1991 off-road bike of the year. But mass production has been dogged by problems.

Nobody has attempted to mould such large chunks of magnesium before. Kirk Precision owns a 7,000- tonne die-casting machine, one of the world's largest, that operates at extremely high pressures and temperatures. It is very difficult to ensure that conditions inside the mould are exactly right - allowing the metal to fill the mould smoothly without creating cracks or faults in the frame.

The metal must fill the frame within 45 thousands of a second, and maintain its temperature of around 650C (1,200F). The magnesium atomises inside the mould then solidifies as it cools. If it cools too rapidly the metal will stick to the mould's surfaces. Only 10 per cent of the early frames were usable. Months of fine-tuning finally paid off at the beginning of July. The company is now producing about 425 'raw' and 100 finished frames a day - 85 per cent of them at the standard it requires. Kirk-frame mountain bikes sell under the Dawes label in the UK for between pounds 350 and pounds 600 and are available here now. The racing and town bikes cost about pounds 350 and should be in the shops from next January. The frames on the bikes for sale in the shops in Britain have been designed to weigh about the same as an ordinary cycle but die-casting gives the company the chance to vary the thickness of the frame - strengthening it in the spots where the stresses are greatest and thinning it down where the frame can stand it.

The Lotus bike which helped Chris Boardman win Britain's first gold medal in the Olympic Games has helped to revive interest in bicycle technology. But this machine, with its expensive hollow carbon fibre frame, is designed for the elite cyclist. Kirk Precision is aiming for the mass market.

(Photograph omitted)

Start your day with The Independent, sign up for daily news emails
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
ebooks
ebooksA special investigation by Andy McSmith
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Tradewind Recruitment: Science Teacher

£90 - £140 per day: Tradewind Recruitment: I am currently working in partnersh...

Tradewind Recruitment: Year 3 Primary Teacher

£100 - £150 per day: Tradewind Recruitment: Year 3 Teacher Birmingham Jan 2015...

Ashdown Group: Lead Web Developer (ASP.NET, C#) - City of London

£45000 - £50000 per annum + Excellent benefits: Ashdown Group: Lead Web Develo...

Tradewind Recruitment: Key Stage 2 Teacher Required in Grays

£21000 - £40000 per annum + Negotiable: Tradewind Recruitment: Key Stage 2 tea...

Day In a Page

Isis hostage crisis: The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power

Isis hostage crisis

The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power, says Robert Fisk
Missing salvage expert who found $50m of sunken treasure before disappearing, tracked down at last

The runaway buccaneers and the ship full of gold

Salvage expert Tommy Thompson found sunken treasure worth millions. Then he vanished... until now
Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Maverick artist Grayson Perry backs our campaign
Assisted Dying Bill: I want to be able to decide about my own death - I want to have control of my life

Assisted Dying Bill: 'I want control of my life'

This week the Assisted Dying Bill is debated in the Lords. Virginia Ironside, who has already made plans for her own self-deliverance, argues that it's time we allowed people a humane, compassionate death
Move over, kale - cabbage is the new rising star

Cabbage is king again

Sophie Morris banishes thoughts of soggy school dinners and turns over a new leaf
11 best winter skin treats

Give your moisturiser a helping hand: 11 best winter skin treats

Get an extra boost of nourishment from one of these hard-working products
Paul Scholes column: The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him

Paul Scholes column

The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him
Frank Warren column: No cigar, but pots of money: here come the Cubans

Frank Warren's Ringside

No cigar, but pots of money: here come the Cubans
Isis hostage crisis: Militant group stands strong as its numerous enemies fail to find a common plan to defeat it

Isis stands strong as its numerous enemies fail to find a common plan to defeat it

The jihadis are being squeezed militarily and economically, but there is no sign of an implosion, says Patrick Cockburn
Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action

Virtual reality: Seeing is believing

Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action
Homeless Veterans appeal: MP says Coalition ‘not doing enough’

Homeless Veterans appeal

MP says Coalition ‘not doing enough’ to help
Larry David, Steve Coogan and other comedians share stories of depression in new documentary

Comedians share stories of depression

The director of the new documentary, Kevin Pollak, tells Jessica Barrett how he got them to talk
Has The Archers lost the plot with it's spicy storylines?

Has The Archers lost the plot?

A growing number of listeners are voicing their discontent over the rural soap's spicy storylines; so loudly that even the BBC's director-general seems worried, says Simon Kelner
English Heritage adds 14 post-war office buildings to its protected lists

14 office buildings added to protected lists

Christopher Beanland explores the underrated appeal of these palaces of pen-pushing
Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Scientists unearthed the cranial fragments from Manot Cave in West Galilee