This is not likely a BikeCAD specific issue. I suspect the circle shown below will appear similarly distorted on your monitor. I seem to recall that you are using a PC. On Windows, you should go into your control panel by clicking on the Windows logo on the bottom left corner of your screen and choosing Control Panel. If you are using two monitors, you may be able to fix the issue by going into the Display section of your control panel and ensuring that the screen resolution is correctly assigned for each monitor. However, assuming you are just using the one monitor, you may need to look for a special control panel for your particular graphics card. You should still find this in your main control panel, but what it's called will depend on the make of your video card. Possibilities include NVIDIA Control Panel, ATI Control Panel, AMD Control Panel, etc. Each of these should offer some sort of aspect ratio control.