This site may be of interest
http://www.cycleni.com/
My daughter lives in NI and I am sometimes allowed to take my bike when we go visiting. I have done the Strangford Lough Trail a number of times using the NCN route and a pure road route and it’s a great days cycling. Prefer the anti-clockwise circuit (Comber towards Downpartick, Strangford ferry). The wind can be a bit of a devil and coffee stops can be some distance apart.
By comparison I have also completed the Longshore Trail and it is a ride while interesting it’s not one I would rush to do again. Many may disagree it’s just my opinion. Both can they reached from Belfast with ease.
The local drivers appear to be more tolerant of cyclist in NI and I found that you are more likely to get a wave and a grin than a short sharp blast of a car horn and mouth full of abuse.
The first time I visited Newtownards I was unsure to the route, so I stopped in the town to check the map, just about got it opened when a lady walking her dog stopped said in a delicious lilting accent “It will the road to Greyabbey you will be looking for, its down that way (pointing up the road) follow the road left and then right.” She then smiled and wandered off window shopping as she went.
That’s why I like cycling in NI.
