Cycling tends to be kind to knees as opposed to other activities in that the body weight is carried by the bike. It's a good idea to keep your knees warm as cold can affect the knees' capacity to lubricate themselves. Spin rather than push hard in a big gear and allow the knees time get to operating efficiency before pouring it on. As has been said pedals giving a generous amount of float is needed so that the knees can find their natural position when pedalling. Good luck.