Hi Karthik,
There is no way that cycling regularly is related to impotency. As you are a regular cycler, you should be aware of your posture and bike seat adjustment. Keep the following points in mind while cycling :
1. Keep your back straight.
2. Look straight on the path rather than looking down so as to keep your neck straight.
3. Adjust your seat height so as that your knees remains slight bend when the pedal is at its lowest side. This would avoid any jerk to your knee joint.
4. Pedal with ball of your foot.