Hi there, i have a knee pain it's moderate, but sometimes when i sit and flex my knee, i can say it's 4/10, when i use bicycle i feel slight pain, on x-ray my doctor said it's ok, lab results (gout, ra) negative, what type of exercise is good for me?

I recommend obtaining a definitive diagnosis after evaluation & appropriate testing by an orthopedic specialist. Only then can proper treatment, exercises and physical therapy be prescribed. I don't recommend any activities or exercises that provoke your knee pain.

Is this knee pain caused by riding your bicycle ? Do you ride hills? A doctor with knowledge might be of help. Your leg should form approximately a 120* degree angle when on a pedal. Stretching of your quadricep muscles is also important.