Could I suggest that you hire a bike for a week and see why most of the time cyclists do use bike lanes, but some of the time they don't. It shouldn't take you too long to see.
To be honest Mr. Burgess, I would not risk getting on a bike around Dublin city as I think it's too dangerous... and I blame bad infrastructure for that, well ahead of anything else (but I do acknowledge, bad drivers, bad pedestrians, bad cyclists also have to get a mention as adding to the danger) !.
There is a cyclist stop place at some junctions to make it safe for cyclists to proceed through a junction without having to compete with drivers like yourself who clearly thinks that they should not be on the road at all.
Brendan
While you are correct that I don't think cyclists should be on the road, that is in the context of them not being on the road because roads are for cars, buses etc. Likewise, I don't think cyclists should be on footpaths, because they are for pedestrians. Bikes should be in specific, "ring fenced" bike lanes, kept entirely clear from other commuters, regardless of whether they are in a car, on a bus, or walking. That way, everyone gets to progress in relative safety.
So, what's wrong with my theory - one simple thing, our lack of appropriate resources, and that boils down to the incompetence of the likes of the DCC, who led by Owen Keegan, have put the cart before the horse, by promoting cycling without providing a safe, satisfactory environment, for the cyclists they want commuting.
I know money doesn't grow on trees, so the DCC can't produce endless bike lanes overnight, but equally, there are numerous simple and sensible things that they could do, to improve the situation very quickly. An example off the top of my head, is this nonsense that they've carried on with, with regards to the proposed bike lane along Fairview (Dublin 3), rather than do the sensible thing and put the cycle lane through Fairview park (alongside the pedestrian footpaths already there, easily lit up, safe from traffic, not taking away valuable limited road space etc.), they've proposed several other stupid alternatives.
If anyone from the DCC happens to be reading this, then please take note - painting a few white lines on main roads, full of motor powered traffic having to commute in and out of a city, is not a safe or satisfactory solution.