Thinking of renting bikes for an easy afternoon bike ride/picnic in August 2021. Any good bike trails near the port there?
Did not do any digging, but looks like there may be some info at that site you may find useful.
The link posted above contains everything you need to know, even if it is more about longer bike trips. But Bornholm is a great place for bike trips. The island is small enough that you can easily cover it by bike and there is plenty of things to see.
Strava is a great site for discovering bike trails and mapping routes worldwide. I've used it often to find cycle superhighways in Denmark & Netherlands.