A racing bike frame basically lasts forever - only the stylish shell suffers over the years. Paint becomes dull, scuff marks and scratches make the bike unsightly, or the decor is completely out of fashion. The good news: it doesn't always have to be a new bike; a successful renovation can also rekindle the joy of your faithful companion.
However, the first step before repainting is to remove the old coating from the frame. For a new wet paint job, it is sufficient to mechanically remove any loose paint residue and simply sand down the old, still adhering paint. For powder coating or anodising, however, the frame must be completely bare. As sanding down a bicycle frame is an enormously detailed and time-consuming job, there are aids available for this purpose. Chemical paint strippers can make the preparation easier for metal frames, but not everyone is comfortable with the toxic substances. It is easier to have the frame stripped of paint by a specialist; most paint shops offer this service. Mechanical blasting, in which solid particles shoot the old paint off the surface at high pressure, is generally the most cost-effective solution, but is not suitable for all materials. Sandblasting is only an option for simple steel frames with thick-walled tubes, as the sharp-edged quartz sand not only attacks the paint but also the metal. High-quality, thin-walled steel frames and aluminium frames should be blasted gently with glass beads or dry ice. Neither blasting nor stripping is an option for carbon: "You never know what fibres and resins the material is based on, so chemical processes are out of the question. And blasting methods not only ruin the paint, but also the carbon structure," says paint expert Martin Jahnicke from the design agency EtoE. "That's why the only option with carbon is sanding." Depending on the frame shape and paint finish, this can cost several hundred euros.
Problem case carbon
For carbon, there is no alternative to sanding, but also to coating: the material cannot be powder-coated or anodised, only wet paint is an option. This is not a flaw, on the contrary: there are virtually no limits to the design options - from single-colour matt paint for just under 100 euros to elaborate airbrush motifs, which can cost four-figure sums depending on the effort involved, everything is possible. The glossy, smooth surface of a well-executed wet paint finish is unrivalled. This type of finish also weighs very little, between 50 and 150 grams depending on the colour and design. The low coating thickness also allows engravings and finely filed joints on restored steel frames, for example, to be shown to their best advantage. However, only a few painters are good with bicycle frames. Martin Jahnicke explains why: "Because the tube composite does not have large surfaces, an even coating thickness on all tubes requires a lot of practice. Otherwise, paint noses and imperfections quickly appear. It is also difficult to check during work, as the pipes reflect light poorly. You have to be able to paint a bicycle frame virtually blind, and that's something you simply have to learn." If you want a professional result, it is therefore advisable to go to a specialist.
In addition to classic wet painting, other coatings are also possible for metal frames. They can be tougher and more impact-resistant, but are sometimes limited in their design options. Powder coating has proven itself for steel and aluminium, in which a fine plastic granulate is first applied to the frame, which adheres to the metal thanks to different electrical charges and is evenly distributed. During heat treatment in an oven, the granulate melts and bonds to form a closed, even plastic layer. An additional layer of clear powder can give the previously matt surface an almost lacquer-like lustre. "There is a wide range of colours, and multi-colour designs, metallic effects and, thanks to heat-resistant paints, even airbrush patterns are now possible, which are then protected under clear powder," explains coating expert Christian Brandes from Gifhorn in northern Germany. The powder-coated layer is tough and flexible and therefore less susceptible to scratches and knocks. The disadvantage: a powder coating weighs around 50 to 100 grams more than a comparable paint finish, and the layer is thicker; when restoring the appearance of steel frames, it can clog engravings or details on elaborately crafted joints and thus spoil the fine appearance. Water can also infiltrate the powder layer in damaged areas, which is something to be particularly careful of with steel frames. Alternatively, welded aluminium frames can also be anodised. In this process, the top metal layer is electrochemically converted into an oxide in an acid bath, which can also be coloured differently. The shimmering metallic surface creates a very unique look - with the typical appearance of anodised tuning parts. A special case is hard anodising, which produces a significantly harder and more robust surface; however, this can only be colourless or black.
Anodising with uncertainties
In principle, anodising always involves a certain risk: on the one hand, the exact colour shade depends on the alloy of the frame and can hardly be predicted precisely. Secondly, irregularities in the alloy and the surface finish or structural changes to the weld seams can cause stains or colour deviations. "If the frame has already been anodised or is also offered as an anodised version, you can expect a good result. Otherwise, we can't guarantee a perfect result as we usually don't know the alloy composition," says Martin Wolf from EasyElox in Munich. Remnants of removed lettering can also affect the result. Thorough pre-treatment is therefore all the more important when anodising. The specialist companies listed in the column on the right usually offer professional processes.
THEY CAN DO IT
Selected specialist companies specialising in bicycle frames
EtoE
09337 Hohenstein-Ernstthal
Painting/Airbrush
www.etoe.de
Heuser Design
65558 Kaltenholzhausen
Painting/Airbrush
www.heuser-design.de
Rockenstein GmbH
98553 Schleusingen
Painting, powder coating
www.rockenstein-gmbh.de
Bikecolours
61250 Usingen
Powder coating
www.bikecolours.de
Brandes Powder Coating
38518 Gifhorn
Powder coating
www.brandes-gmbh.de
Goetz Powder Coating
70736 Fellbach
Powder coating
www.goetz-pulverbeschichtung.de
EasyElox Eloxal Service
81373 Munich
Anodising
www.easyelox.de
Anodising Munich Heinitz GmbH
85560 Ebersberg
Anodising
www.eloxal-muenchen.de
Diener & Rapp
Anodising company GmbH
78056 VS-Schwenningen
Anodising
www.dienerrapp.de
