Well, semi-rimless glasses are very popular with many people. To clean them, you should follow some steps. For example, if the lens is merely dirty and not covered in abundant grease and grim, you can use a good quality linen or cotton cloth which will work wonders. Then, you can also use some resolution to clean it one more time. So that it can be effective to your glasses. And then, for the surface of the nose pad and the frames, you can also soak them for a couple of hours in warm water to loosen the residue. Then it will be easy to gently brush away the unwanted dirt with an old soft bristle brush or old toothbrush. Anyway, you should do the entire task in a gentle way so that you will not damage your glasses. And I will also remind you that you should take care for your frames, when you have sports.