FFor the few who really care what material the frame of their bike is made of, the question “steel or aluminum?” no longer arises. That was the subject of a discussion the day before yesterday. When it comes to maximum tensile strength, i.e. stiffness with the lowest weight, a carbon frame offers the best values. Today it no longer comes from a witch’s kitchen, in which you have to shell out a small fortune for the magician, but is baked industrially. Mountain bikers with ambition as well as racing cyclists can hardly avoid carbon. From the main frame to the fork, stem and handlebars to the seat post and a seat shell, not to forget the wheels: Everywhere in really sporty bikes, the fiber paths follow the lines of the forces that act in and on the components.
On the other hand, aluminum dominates the field on a broad front, from cheap everyday bicycles to expensive electric bicycles. That was not always so. Aluminum has been used in the construction of bicycles since the last decade of the 19th century. But it wasn’t until 1977 that Kettler’s “Alu-Rad 2600” established itself successfully on the market as the first mass-produced bicycle with a welded aluminum frame. The promise was to make a rustproof bike lighter through the aluminum frame. That worked, at least according to the numbers on paper.
However, a few lessons had to be learned: Frames made of aluminum can corrode and can only be joined as permanently as comparatively filigree frames made of steel with much more powerfully dimensioned tubular profiles. So the weight loss isn’t exactly breathtaking. Above all, an aluminum frame is less elastic than a steel frame. This loss of comfort was just right for the industry. The era of suspension forks and suspension seat posts began with the aluminum frame, which finally put an end to the weight advantage of aluminum. Even before carbon began to prevail over stainless steel tubes, aluminum alloys such as 6061 and 7005 replaced “bicycle steel from tram rails”. Today aluminum is shown hydroformed as the usual, for a little more money also in almost as free lines as carbon laminate makes possible, hydroformed without comment in bike shops. But steel has become the frame material for connoisseurs and enthusiasts.
From steel – selectable quality – you can, for example, have a traditionally lugged frame soldered by hand for a bicycle at Patria in 33818 Leopoldshöhe, which fits after a first fitting like a tuxedo from a men’s tailor after the last. Steel is a common choice of touring cyclists. They repeatedly point out that every blacksmith in the Hindu Kush can fix a broken frame. You just want to know how often that actually happened. Today, steel is primarily the material of nostalgics, the owls who use a 1980s bird of paradise by Ernesto Colnago with butted Columbus tubes to fetch the rolls. And unfortunately, many a frame made of tubes, on which the stainless steel labels from Tange, Reynolds or Mannesmann are stuck, is beaten to the cafeteria on pedal axles that have been trampled at an angle until the bulky waste collector arrives.
It is rare that you can get the same bike with either a steel or an aluminum frame. One would expect this more from a manufacturer and in higher price regions. But the affordable lifestyle brand Excelsior from wholesaler Hartje makes it possible to make a direct comparison. In the spring, the Sputter model was used and now the Gaudy, which is also equipped with a two-speed centrifugal automatic system. The pastel turquoise lacquered wheel is not gaudy to the point of tastelessness. Rather, it is so reduced to the bare essentials that a sticker says that it should not be used in traffic. You have to retrofit lights, bells and reflectors.
The two Excelsior bikes are not identical twins. Apart from the material of the frames, their geometry differs slightly. A big plus point: The Gaudy, which runs on narrow 23 mm tires, is factory-fitted with a 2: 1 ratio, which harmonises better with the relentlessly upshifting hub at around 17.5 km / h with a factor of 1.38. At a price of almost 370 euros, the steel frame can only be of the “I-was-a-tram-rail” type and not stainless steel. A knock on the pipes and you can hear it. The pretty Gaudy is around 12 kilograms, as expected, about one kilogram heavier than the sputter with the aluminum frame.
In any case, the Gaudy is the more comfortable city bike. Steel can withstand road bumps better, it also accompanies the effort of the person on the saddle with a certain flexibility, so it consumes energy through elastic deformation. This is highly undesirable in sport, but feels good in everyday life. The steel can rust where the paint has peeled off, and it will tire even with the best care. But there is still a while until then.