'off season' longs

My bike riding is reduced, as I can't stand to be on the trainer more than an hour, and outside rides are out until the sun returns for the early evening hours.  My running and swimming have actually increased, in the case of running, dramatically, as I am no longer worried as much about getting injured and missing a race.  Of course I have a long way to go before I'm considered to be "doing a lot" anyway. 

so, my averages are 1 hour on bike 4x week, 45 minutes swimming 2x week, and running 1 hour 1x a week/30 minutes 3x a week.

First, my base is far from incredible (but thanks for the compliment ).

Second, only when I train for a marathon (twice now) have I ever gotten NEAR a 3 hour run.  I would NOT recommend this to anybody.  2 hours is plenty.  2.5 if you feel you need to go longer to cover more distance.

I would also NEVER encourage anybody to ride the trainer for 4-6 hours!  If you were training for IM and forced to do it, fine.  Otherwise, I'd encourage you to ride much shorter (2 hours is MORE than enough) and much harder.  Go longer when you can get outside. 

This is partly related to the "build fast" now and add "far" later that running2far notes above.  In fact, if you're interested, there's a free webinar this weekend by the guys at EN.  It's to push their program, but probably has some useful info for anybody to think about in planning their training.  In short, "base" isn't just about going for a long(er) time at a slow(er) pace.

I had a lot of issues with deep fades in marys and experimented with the intermediate plan on cool runnings for my last mary.  It was mileage based and championed more 20+ runs with a long of 26.  The caveat is that you do this easier than race day obviously (they suggest 90-120 seconds over 10k pace).  All in, I think I had a 20, 24 and 26.2 (like I was not going to cover the full distance when they said 26, cmon)  Their logic was that it would help on race day knowing you could cover the distance but it also give you a heads up what to expect in those last tough 5-6 miles.  Dunno, probably not for everyone, but just wanted to post it as an aside on the comment as I followed a plan similar to this and it topped me out about 3:35 though hydration has changed some of that.  End result on this plan was 25 min PR and a trip to Boston.  Ultimately do what works for you and your body, but just wanted to throw some evidence from the go longer for mary training camp, which I know is the minority.  And I would say that is if you are racing it vs running it to finish. 

For your transition and early base period, I would focus more on frequency, than duration.  Within my own training (these days, not when I was racing elite); I like to have one day a week that is endurance focused.  Right now that means I might do something like... ride to a local park, hike up a mtn, ride home -- about 3-4 hours of low HR cross training.

 So I wouldn't even worry about "long" anything in terms of tri-specific.  Goal for the first six weeks back is establishing workout frequency, skills development and gradual endurance development.

 After 6-8 weeks of that, then you might consider a couple of 10-14 day blocks where you do your weakest sport quite often.  I call these "camps" -- swim camp and/or run camp can be a great way to change things up and make progress in the winter.

 Hope this helps,

 gordo