Patients who have had an anterior cruciate ligament tear and repair must follow the doctor's and the therapist's guidelines after surgery. This is to avoid forces on the healing tissue that could tear it again.
Progressive resistive exercises known as "PREs" to therapists are avoided early on in rehab. This applies to the first 30 degrees of knee flexion. A good rehab program will take into consideration your drive and need to return to bike action. There are many other parts of the body to exercise!
Strength training for the knee usually begins within the available range of motion and not beyond. This may frustrate you and cause you to "push" yourself. You may find comfort in the new findings that show overall muscle strength around the knee improves even when only a small arc of motion is exercised.
Don't put your new tissue graft at risk. Follow your doctor and therapist's advice carefully. In the end, you'll be back on your bike better than ever.