thank you for your answer. I try to learn about gears and crank sizes. 50/34 is better than 53/39? I try to setup my bike be okay for fast rides. I have wheels with 9 speeds cassete 12-25 i use in two road bikes i have the crank too. But because the rear wheel have start do pinch flat 6 times. Looks i need new rim tape. Until i fix that i use wheels with freewheel 6 speeds 14-28. I wonder if that freewheel is be okay for now for fast rides. I know is have missing the 12 and 13 cog i have in the cassete. And is more wide