Right now that first, obvious answer is out of the way…
80km from the port to redcross via the coast rd. Redcross has a lovely campsite which is attached to the pub which has a brewery and german brewmeister and the beer all complies with the german purity laws. om nom nom.
Then a gentle 50km along part of the avoca valley up to aughavannagh then across to glandalough via the sleive maan and shay elliots climbs, and carry on to roundwood campsite. 6-7 pubs, all very good (Coach house is v bike friendly).
3km up to ballinstoe and rent a mtb from biking.ie and do a loop, then go over the boardwalks to Djouce (or via the road) and enjoy the finest mtb playground in ireland. Then back to roundwood and another nights camp.
Then do the wicklow gap toward ballymore eustace around the lake and then back over the sally gap to the sugarloaf mountain and then down to the valleystop campsite (~90km).
Last day – Up to ticknock and rent a mtb from biking.ie their 2nd place in the dublin bit of the mountains and ride around probably the 2nd most mtb built up area in ireland. Then straight down all the way to the ferry.
😉
All the main east coast road climbs, 2 of the best mtb places in ireland and good campsites in nice and handy places.