Best of luck with commuting, and your new job.
You have two options if you don’t or can’t drive.
Either you take the train in Laytown (there is a locked shed for bicycles) and walk, or use buses. Don’t think it’s practical to rathmines, but not sure as my geography is a bit off. There is some people who have a foldable bike that can be brought in the train, but the wheels are very small, not great if you have to cycle a lot.
Or you can use Matthews coaches up to city centre (north side~) and cycle towork. You can put your bicycle for free in the coach (boot).
But dublin 8 seems to be far from O connell street, but cycling doesn’t take too muh time once you’re use to it.
But maybe at work some people are coming from around here and you can try to organise some car pooling system.
Hope you’ll find a solution.
Take care,
Fabienne