so i injured my knee, totally non cycling related

tripped over my dog ( 200lb bullmastiff) jammed an iron rod into the inside of my knee then slammed it into a 4x4 post. sweet huh ?

so i am finally back to walking regularly with minimal pain after 2 months. There was no permanent damage according to x-ray and mri.

how easy should i take it getting back to riding? i rode a little 5 mile trip and seemed fine, but it was on my cruiser. Should i go ahead and try a flat 20 miles or so ? see how it goes?