I've cycled all three of the Aran Islands (Inishman, Inishmoor, Inishmeer, or something like that). In terms of road conditions, they're all crushed gravel - no high speed thrill rides here. Along most of the roads are lined stone walls about 3 feet high. All the islands are very small, so not much in the way of racking up miles. I went there mostly as a side trip when I was heading to Galway.