€2 for 90 minutes of travel across Dublin Bus, Go Ahead, Luas, DART and Commuter Rail with Leap card

Does the 90 minute window end when you log on on a return or when you log off at destiation?

90 mins after you log on for your first journey. You can go and return for a single fare, provided you tag on for the return within 90 mins of the first tag-on (I think).

Sorry, couldn't resist. To answer. Yes, I think Balbriggan is most northerly point in the Short Hop Zone so €2 will cover you to Malahide (or further south) from there.

EDIT: Actually just looked it up and Balbriggan is in zone 6 and 90 minutes is €3.90 here but fare calculator shows Balbriggan to Malahide as €2.

Train and tram map here https://www.transportforireland.ie/getting-around/network-maps/dublin-area-train-tram-services/

AFAIK the €2 fare covers the entire Luas and Dublin Bus networks (including the bits of the latter operated by Go-Ahead) but there are a few outer train stations (Greystones and Balbriggan are 2 of them) where the fare is higher, though you still get the 90 minute transfer

check the fare here https://www.irishrail.ie/en-ie/rail-fares-and-tickets/fares-info/dart-and-short-hop-zone

if the station is in the Short Hop zone the fare also covers 90 minutes transfer to bus or luas.

Always tag on and tag off for tram and train. If switching bus, always tag on when boarding bus. The system will do the calculations for you.

If you don't tag off a bus (which I think you can't) how does it know to only charge you the €2?

Or are all bus journeys less than 90 mins?

The 90mins is to the start of the last trip. You could take 89 minutes and then get on a 65 to Ballyknockan and it'd still be €2

Because that isn't how it works, as I just explained. But to clarify:

The 90 minutes is the allowed time to get on another form of transport. How long you are on that is completely and utterly irrelevant (once its not a train going beyond the limits). The total trip can take 200+ minutes if you took that specific example of getting the bus to Ballyknockan at 89 minutes.

If you only take one trip, its just €2 flat. that's it. No concern about the 90mins. It can take 1 minute or as long as the trip can possibly take - there is no full fare, the fare is €2

I dont even think i have a login. I usually just put the card to the phone. Though im a bit rusty on this leap stuff. Only started back on public transport in the last couple of weeks :)

Staying in my in laws in Rush for the rest of the week and going to the city center so i'll give it a go on the way in and on the way back.