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The return of the aluminium frame

Heating aluminium
Mike Hawkins
4 Sep 2015

Aluminium may have been usurped by carbon as the frame material of choice but it's making a comeback at the top end.

Aluminium’s reign at the top of the cycling tree was relatively short-lived. As a material for pro race-winning bikes, it only really took over from steel in the 1990s, and by the start of the new millennium the tide was already turning in favour of carbon fibre. Marco Pantani was the last man to win the Tour de France on an aluminium bike – a Bianchi Mega Pro XL – in 1998, and after Spaniard Igor Astaloa won the 2003 Road World Championships aboard a Cannondale CAAD7, aluminium bikes soon disappeared from the pro peloton altogether.

It may seem that aluminium (more specifically aluminium alloy) has been relegated to the cheap-and-cheerful end of the road bike market, yet several manufacturers have continued to make top-end, race-ready alloy road bikes, and other manufacturers are even returning to alloy as an alternative to carbon.

Trek has recently released the Émonda ALR, an alloy addition to a range that initially included only its lightest carbon bikes. BMC too has just produced an alloy version of its Tour-winning Teammachine (coincidentally also called ALR). Specialized has had an S-Works edition of its popular aluminium Allez bike for some time, that retails at a whopping £7,500 complete with Dura-Ace Di2 groupset, and Cannondale continues to refine its expertise in the alloy arena with the launch of the CAAD12 to supersede its highly regarded CAAD10. 

Second coming

So why is the bike industry suddenly so interested in old-fashioned metal when it has hi-tech black fibres to play with? Thomas McDonald of BMC, a brand with a strong history in the aluminium sector, says, ‘In general, what we saw with carbon was it creeping into some really entry-level price points. The cost of the frame meant that the rest of the bike was being compromised [to meet the price point] and left retailers short of confidence.’ 

Aluminium drop

Where once carbon bikes were reserved for only the pros and the well-heeled, they have increasingly become more affordable, but because even the cheapest carbon frames are reasonably expensive to produce, brands have been using cheap wheels and components to keep the overall price down, which can result in a poor ride quality and ultimately negate all the benefits of the carbon frame.

Even the most advanced aluminium frames are comparatively cheap to produce when compared to carbon fibre so, when they’re matched with high-end components, an alloy bike can potentially offer a superior overall ride experience compared to a lower-end carbon bike at a similar price.

‘Also I think there are a few brands who never walked away from aluminium, who always continue to push and who are still having success,’ McDonald adds. He doesn’t mention any names, but most likely at the top of his list is Cannondale, arguably the high priest of aluminium, basing its reputation on race-winning alloy bikes that carry the name CAAD (Cannondale Advanced Aluminium Design). 

Cannondale’s senior project engineer, Chris Dodman, gives us his take on why Cannondale has never truly let alloy go: ‘Having had so much experience in designing, testing and manufacturing aluminium frames since the late 1980s we have always seen the potential of remaining in aluminium. Other manufacturers may have switched focus to different materials more than we have, but aluminium’s our heritage and that’s a key driver here.’ Neil Webb, founder of British bike brand Bowman, explains more of the benefits: ‘Bowman has gone down the metallic, as opposed to composite route, because of the design flexibility offered. Our first frame was destined to be one that could be raced, but still be accessible price-wise, so that kicked steel off the table. Race-weight steel frames are possible – just – but are prohibitively expensive. Titanium has similar issues. Which left aluminium. 

‘Then the design process is so much faster,’ he adds. ‘If you buy enough tubing for three frames, you can get three different prototypes made up relatively quickly and test them all. With carbon, you’d need to develop and make three different moulds (or at least mould adaptations) before you can begin to make your prototypes, which is excessively costly and very time consuming.’

95% aluminium

Aluminium might allow faster and cheaper development of frames, but just what are its properties as a frame material? Alloys of aluminium are classified as wrought alloys and come in a bewildering number of precisely controlled mixes depending on what characteristics you want from it. Aluminium is the primary metal, usually at around 95% by weight, but others ingredients such as silicon, iron and copper are frequently added to create each blend that is then classified by a number, such as 7005, or if it’s a manufacturer’s own formulation it will carry their name as a proprietary blend. 

Over the years the most suitable alloys for various bike parts have been refined to the point that today you’ll find the vast majority of aluminium parts, from frame tubes to hubs, come from one of six grades. They’ve been selected for their characteristics both in terms of how they stand up to the abuse of riding but also what’s actually involved in forming the component part. For instance, does it require forging, machining or welding? Some of the larger manufacturers have developed their own alloys in an effort to optimise the properties required to suit their preferred manufacturing techniques, particularly in the search for reduced wall thickness in tubing to keep weight low while maintaining strength, durability and ride quality – at a cost.

Melting aluminium

BMC, however, seems happy to stick with the widely available alloys and instead concentrate on developing tube shapes to form the characteristics of the ride. ‘Marketing jargon aside, most brands use the same types of aluminium, just as we are all operating off the same types of carbon,’ says McDonald. ‘Yes, there are very subtle differences in materials but effectively what we have learned is that tube shaping actually makes more of a difference than the type of material we use, within the bounds of high grade aluminium. So the stance we took with our latest alloy frame – the ALR Teammachine – was to go the extra mile and exercise some radical tube shapes, even though it’s not the most cost effective thing for us to do.’

Cannondale claims it was equally focused on the tube design side of the process when producing its new CAAD12 aluminium frame. ‘The CAAD12 is a radical frame in terms of the way we approached the design,’ says Dodman. ‘The way the industry was designing frames was to follow a building block-like process. The analogy I use is this: if you’re planning a route from A to B across a city you know, you’ll link up all the bits you have in mind to create your route, whereas if you simply put your destination into a modern GPS you’ll likely get a more efficient route, taking into account all the variables that will affect your journey. It will likely not be the route you would have chosen.’

What Dodman is alluding to is that previous experience and knowledge can be incredibly valuable, but sometimes your worst enemy, preventing you from really considering what the alternatives might be. A completely new frame design sometimes requires you to throw out those old building blocks and let available technology guide you. 

So what’s his GPS? ‘We call it Tube Flow Modelling,’ Dodman says. ‘We completely changed the way we modelled tubes from the outset – even the way we put the information in the system and the way we let go of a lot of the control we used to feel that we needed on certain things. It allows the tube to flow from end to end around all the constraints in as smooth a way as possible.’ (Read more about this in an upcoming piece on the new CAAD12).

Born again

The irony here is that aluminium alloy is being rejuvenated and brought back to manufacturers’ line-ups through technology that has been learned, modelled and refined by its replacement: carbon. By focusing on tube shaping in metal frames with the understanding of what ride characteristics were desirable, based on the directions that carbon frames have taken them, manufacturers have been able to breath new life into aluminium.

To try to unravel some of the differences both in terms of weight and cost we spoke to Italian tube manufacturer Dedacciai, one of only a very select group of tubeset manufacturers that also produces its own bike range, in both carbon and aluminium. We’ve already alluded to the fact that carbon costs more and weighs less than aluminium, but by just how much? 

Pouring aluminium

Dedacciai Strada’s export manager, Max Gatti, puts it like this: ‘If we compare high-quality products, our road racing aluminum frame usually weighs 1,100-1,300g, and a road racing carbon frame weighs 900-1,100g. The difference of raw material costs is approximately 1:4 [in favour of aluminium].’ 

Cannondale’s Dodman estimates the cost ratio to be slightly higher. ‘As a raw material aluminium is about one sixth of the price of carbon fibre prepreg, and a top-end aluminium frame costs about half what an entry-level carbon frame costs in just materials and labour.’

Costs, then, are heavily skewed in favour of alloy, but that’s only part of the story. Trek Bikes senior product manager Ben Coates says, ‘It’s a fundamental fact that aluminium bikes can be made for a lower cost than carbon, so if you value higher wheel spec or a higher-tier groupset, you’re effectively trading them for carbon fibre. As for the other benefits, an aluminium bike is going to feel like it transfers power faster, and is usually lighter compared to carbon at the same price. So it depends on your use and your values. Everyone knows a crit racer on an aluminium bike can crash it and not be as worried about the cost of replacing a frame. And there’s still a chance you might be able get up and race it to the finish.’

Making the choice

With this renewed interest in aluminium and an influx of mid/high-end race-ready frames, an overlap is forming in the market where consumers may well find that some aluminium bikes are on sale at a similar or higher price to some carbon models. So, if you go into a bike shop with a grand or so to spend, should you opt for a carbon bike or an aluminium one?

Cannondale’s product manager David Devine says, ‘Remember that not all carbon is created equal. When you’re shopping at a £1,300 price point the carbon is often moulded with the price in mind, and the result is frames at this price are regularly heavier than aluminium. Our CAAD12 weighs 1,098g in size 56cm. We also tried to narrow the gap between aluminium and carbon in terms of the ride, matching the stiffness numbers and comfort of our Evo carbon frame. But from there [due to lower frame cost] customers can receive greater spec price value from the CAAD12 compared to the Evo platform.’ 

At a particular price point – £1,000 to £1,500 – it could be that an aluminium bike is lighter, just as stiff, and significantly better specced than its carbon rivals. There will always be those who feel aluminium is simply not as desirable as carbon, but if you can see past the issue of perception then you are only left with one other factor to consider: how best to sneak another bike into the garage without the other half noticing.

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