Why can I see the carbon lay-up of my frame through the clear coat?
BMC’s frames are made mostly using UD carbon fibre. UD stands for unidirectional. Unlike more traditional carbon fibre products that use a woven carbon finish (criss-crossed finish like a woven piece of material), UD carbon is literally a piece of carbon material with the filaments all running in one direction. BMC’s frames are made from many different pieces of UD carbon that are woven together, similar to what is done in textile production. Some of our frames contain around 350 individual pieces of carbon fibre that go into the mould before heating and curing takes place. These material sheets - some very small, some very large - are laid at different angles across each other to achieve different results: torsional strength, compliance areas, rigidity, and so on. The layup of these sheets is extremely important to the end result. This is actually the art of building a carbon fibre frame.
On our unpainted frames, you can see the result of these carbon fibre sheets overlapping each other through the clear coat covering the frame. We are actually very proud to be able to show this real effect on our frames. It shows not only the true workmanship of the frame, but also the resulting quality as the frame exits our moulds. Many bike manufacturers prefer to paint their frames because there are often many imperfections in the finish that need to be re-worked using a filler before waiting for it to dry, sanding it, and then giving it a final paint job (a bit like a panel shop). This is a cheaper way to finish the frames, ensures you have no reject quantity, and allows you to use less stringent production techniques.
On unpainted BMC frames, when you look 'into' the frame, you see the actual quality of what’s on the inside – we are showing you our finish and quality and we are very proud of that.