I am fairly new to the wonderful world of icon design and I have a recurring issue that I find difficult to deal with. for me, consistency in line thickness, shape sizes and colors is very important to create a well designed piece.
However I seem to run into an 'optical illusion' problem often. The latest icon I am creating for example should represent an old bike. I have set my line stroke to 10px and have drawn a small circle of 10x10px. Yet all three of my shapes seem to be of different size and line thickness to the eye.
However as you can see by the orange balls I included, the lines really are all the same size.
How do I prevent such things from happening? It looks very awkward to me. I could reduce and increase the size here and there so it pleases the eye, but then it is not technically correct anymore...