In reply to G0rdrilla:
I rode up the ranger down llanberis then came back up and down the ranger.Great day but tiring.But well worth doing.
Next day,yes the marin trail was good,fast flowing,easy to spot the route and links nicely together.Bit wet and muddy in places,but thats mountain biking.All the route is rideable with quite a few "off cuts"into the woods.I was lucky and met with a local rider by chance and spent the whole day blasting around,clocked 60km by the end of the day,shattered.
Worth doing.
Ive also tried rising round in the hills using the map,did not manage to piece together anything special,not that there is nothing there,just did not have the energy to keep plodding on.It maybe worth see in if any local riders on single track are keen to show you there world.
I know when guys come down south we try to accommodate as best we can,show them our gems.