You need a bike or a long, long walk to get to this one. It's around a 5 mile trip including the long walk in at the end.
I'm not sure it's worth it. Carn Ban is probably more interesting for what it was than what it is now. It was excavated in the early 20C when the chamber was more or less intact but the excavation was filled in and there is little surface remains to be seen now.
Access The cycle route leaves the Arran circular road (A841) at NR970214. If you continue along it, you will also reach Monamore.