This is one of our bike from home routes. The interesting thing is that you have the Biscayne Trail from Old Cutler down to Black Point on 87th Avenue. That's true and correct, but it's only the start. It then becomes a gravel, levy trail from Black Point all the way to Card Sound Road. That levy trail was designated the Biscayne Trail before the 87th Avenue section. You can opt to turn around at the entrance to Biscayne National Park or continue on down to Card Sound. I do not recommend riding on Card Sound Road, but you can turn back up the levy, or you can choose to ride up Tallahassee Road which is dirt road down there and goes back up to the motor speedway but you are no longer on Biscayne trail then. We rode these routes for decades before it was ever a designated trail. Great in the winter months for bird watching and spotting crocs and gators. There are often also manatees in the cross canals near the water gates.