Thanks, great info. I am noticing that all advice in the area usually includes a "there is a beer garden nearby"!
I love that about Germany.
It does seem that the trains leave Brühl to the Köln Hbf every 15 minutes or so, so that gives us a bit of flexibility, especially since our train tickets include a city ticket. I think we can time that. We will ask the Phantasialand folks as well, just to confirm. Like you said they may have options already available.
I love that the directions to Herbands lists bicycle information first. I think we are visiting the Melatenfriedhof Cemetery one day, so kind of in the area even if we don't go early on the trip out. Maybe we will wander over that way.