Originally Posted by
surak
I'm in the camp of 3-4 hours is too short of a ride to care too much about zones when starting out. Provided you properly eat and hydrate, you can always fall back to Z2/Z1 when you burn all your matches. Then each subsequent outing you'll go farther before hitting that point, until you don't.
^^ This, really. Just ride and you'll get a sense of what kind of efforts you can maintain over 3-4 hours. Then slowly try to go faster.
Incidentally, holding high Z2 for a long time is not that trivial. My stupid tri plan has me doing 2:40 at upper Z2 and it isnt easy. Just constantly holding the power and cadence for that duration is an absolute mindf'k. So dont underestimate the value of solid Z2 (never dropping into Z1) for extended periods of time.
But as WhyFi said - structured training comes later. Ride your bike for atleast a year or so by feel. Go hard if you feel like it; slow down if you are tired; limp home if you blow up (as long as you have enough to eat, you will almost always be able to ride home at an easy, recovery pace). Do some shorter, faster rides and do some longer, slower (conversational pace) rides. That will not only build some basic fitness for structured training, but also give you a more stable baseline from which to start structured training.