Back on 'Trek'

I am finally cycling again! In September, I tore my ACL (anterior cruciate ligament) and am still recovering. I have resumed bowling and now I can take to the road again on my TREK bike. Before my accident I had managed to reach 50km in my outings and was hoping to start joining other cyclists on group rides of 80km and to cycle in sicily.
I now need to decide whether to undergo surgery or live with it and build up the supporting muscles. 
ANY ADVISE FROM CYCLISTS AND BOWLERS THAT HAVE SUFFERRED ACL INJURY IS HIGHLY APPRECIATED.