Dun Aengus on Inishmore

Any of the tour vans or pony traps lined up on the pier (if taking the ferry) will include a stop art Dun Aengus - it's the highlight and principal stop of their tour of the island. The drivers are open to any special requests you may have, ie for a little more time at the fort, visits to other island landmarks, etc. Their only major concern will be to get you back to the pier in time for your return ferry. What you choose to do between pickup and dropoff is entirely up to you.
Have to assume that the tour vans operating from the airport (if you fly in) are equally accommodating.
As you're already aware, the ebikes are a pleasant way to spend the day if the weather cooperates.

E-bikes are certainly an option. There’s a sizeable bike parking space with racks outside the small visitor center/museum/ticket desk for Dun Aengus.

On our first visit to the island, we brought rented bicycles (not electronic - don’t think those existed back in 2011!) on the ferry, and my husband rode on to Dun Aengus. I wasn’t up for the ride at the time, and missed seeing it.

Our second visit, four years ago, we flew to Inishmore (better than the ferry), and got to Inishmore via the tour van that picks up next to the sweater factory in Kilronan. The driver dropped us off and waited while we hiked up to the site and a short picnic lunch, then picked us up once we’d hiked back down. On request, he then drove us and hiked with us to see the Wormhole, a geologic feature where waves crash up out of a square space in the ground, making a splashing “geyser.” The route’s not really marked. Without the tour, we wouldn’t have found the Wormhole, but that was a bonus sight!

@Robert, thanks for letting me know about the tour vans and pony traps at the pier. I did see them as we biked around the island but it’s good to know where they stage themselves.

@Cyn, We flew to Inishmore last year. The 7.5 minute flight was so much fun. I was sitting next to the pilot. Did that mean I was his co-pilot? ;-) We took the first flight of the day so we could be there for a couple of hours before the people coming by ferry started to arrive. Last year we stayed in Galway, but next year I’m considering staying in Doolin and taking the ferry. Per the website for the ferry it takes 30 minutes to get to Inishmore. This will be my 3rd time in Ireland and I’m hoping to have some new experiences while still having my daughter choose what we do.

Thanks for this question, Andrea. Looks like I will be going, weather permitting, in June - and had read about the vans, but hadn’t read about pony traps. That could be fun.

I would throw in that spending the night on Inishmore allows you to experience a much different place, once the last ferry leaves.