Some of the different parts that can be adjusted are the seat. The seat sits on a rail so you can move the seat forward and backwards. You can adjust the height up and down. Then you can start looking at the stem, which is a little harder to adjust. This bike actually has an adjustable stem that I can make adjustments on the fly, but some you have to measure the angle and then decide what is the optimal stem and the person may have to go buy a stem.
You can also change the cleat on the shoe if the foot isn't positioned properly too. In a cycling shoe, we call clipless pedals. They clip into the bicycle. These cleats are adjustable in that you can move them forward or backwards, you can rotate them so if the foot isn't positioned properly and it's making the knee improperly positioned, you can adjust that then also. We adjust just the cleat on the foot.
Any everyday cyclists could make some adjustments just with the seat to help at least with the knee angles. Many times people have their seats too low because they want to be able to touch the ground and that creates increased bend in the knee, which ends up causing more problems when they are pedaling.
