Could you dismantle one or both of the children's bikes so that it would fit on as normal baggage? As an alternative, while I realise it is nice to have your own bike, it might work out cheaper just to hire bikes in Westport or Galway than paying the airline to ship your bikes. The going rate is around 15 euro per day per bike.
Co-incidentally I just walked the Great Western Greenway, and noticed that hiring bikes there is big business. One-way hires and childrens bikes are no problem and it shouldn't be an issue to get bikes that take panniers.
The arrangements on Irish Rail for bike carriage are most dissatisfactory and as far as I am aware it is not possible to book a bike ticket at the moment. With three people travelling, car hire for a few days might work out pretty competitive with the train.
At a risk of going off-topic for this forum, as an alternative, I would also suggest the Royal Canal Way which is accessible from Dublin and goes 140km west and is easily managed with mountain bikes. Mostly it is paved or fairly smooth grass and could be managed on a hybrid but a road bike would not be suitable.
Finally I would suggest a bit of caution if cycling with children who haven't cycled in Ireland before and you're planning on getting into the city from the airport. I presume you know the lay of the land, but it is not legal to cycle on footpaths in Ireland. While there are cycle paths in the city, they can end suddenly and force you onto roads. Cycling in Ireland is not like in continental Europe and it would be unusual to see children cycling in the city.
Last edited by James Howard : 06-05-2014 at 09:49.