Is 4:30 doable for me?

I'm assuming you are doing the Patriot and from the numbers you've posted.  I definitely think it's doable. Patriot Bike has changed and to me it's flatter than it was last year. What are you planning to do for Transition times? Last year as you probably know was very very muggy, with that being said if everything goes as planned. I definitely think you will be able to reach your goal.

Scott 

Also change your ">" to "<"  

Boy I sure hope you can break 4:30.  I'm shooting for ~4:30-4:35 for BSLT70.3 in June, and I'm working with less fitness than you. 

For comparisons sake, I'll be about the same time on the swim, 3.8 w/kg on the bike(hoping for 2:30) and while I've been running far less than you, running is my strong suit and I should be under 90min. 

If you execute well, I would expect your goal to be within reach.  You have good volume and great consistency.  Just remember to pace the bike to allow you to run like you need to. 

I have a half marathon this weekend, and my goal is 1:23. If I'm able to get in that range, is 1:30 still a reach for the HIM? Would holding a 7:00 pace (around 1:32 overall) be more doable?

I'm sure there are a lot of people who raced IMTX this weekend who would concur!

Still, it's hard not to go into it with specific time goals.  The only thing more stupid than going into race with a specific time goal (which I'm doing) is to go into a race with specific qualification goals (which I'm doing).  Can't control the conditions or who shows up on race day.

Anyway, Nate, as I said before, I think you're on track for your goals.  Execution/pacing will be key.

Bryan, can you explain what it is in Nate's logs that makes you question his running?

I don't have any idea if you will be able to do it or not.  Seems like a reasonable, but challenging, goal--which is good.  But I'll disagree with Bryan that you need to be doing a lot of running at low-7, high-6 paces in order to run a 1:30.  If you are able to run a HM anywhere near 1:23, you have the ability to run 1:30 in an HIM.  Whether you will or not depends upon all the factors Fred mentioned (probably plus some more).

Thanks for the feedback!

I definitely understand that there are way too many variables to have a very specific time in mind for a longer race, but I like to do it anyway. For shorter races I am usually able to predict my time very accurately.

I'm currently following a Jack Daniels marathon plan, and his VDOT scale currently puts me around 55 or 56, which equates to a 1:23-1:24 open half marathon. Based on this scale, I've been almost spot on for a recent 5k and a 10k. My 'E' pace runs, which are in zone 1 and low zone 2 are in the 7:45-8:05 range, depending on weather and terrain. My tempo runs have been in the 6:25 range, and my interval pace for 1200's and 1-mile repeats is around 5:40-5:50.

I guess I'll just have to see how the day goes. I'm pretty confident that I'll be able to run well off 250 watts on the bike, which is around 78% power. As I said before, the bike and run courses are flat. I imagine that if the temps are in the 60's or 70's I'll do much better than on a 80 degree humid day.

I agree with Johnny.  Maybe different philosophies on run training, but I was able to go mid 1:20s for a stand alone HM and 1:30 for  HIM on very little running and with most of it being 7:30-8 min/mi. 

Might be.  But I'm not sure comparing how you ran with how he's running is fair.  Doing easy runs at those paces is still very much in-line with the kind of time he is aiming for, especially if his tempo runs also fall in the right area (low-mid 6's).  His goals appear a stretch, but doable.  Which is what goals ought to be.

And that may be the big difference.  I would bet you were probably 'capable' of going sub-1:23 in your first year (even if not 1:19).  But you weren't trained specifically to do so.  Your 'stretch' goals were focused elsewhere--for good reason--and that 1:23 was fairly 'comfortable'.  (I say those words knowing full well there is nothing truly 'comfortable' about running that hard--even for you! )

Also, even a 1:25 would tell me that on a good day he should be able to run near 1:30 in an HIM.

That was my thought.  With a 320W FTP, 4.2 W/kg and a decent aero position, I would expect a pretty solid bike split; better than 2:25 at least.  If 2:25 is realistic, then I'm in a whole lot of trouble...

Then again, a 2:25 may be appropriate if it leaves Nate's legs strong enough to ensure the sub 90min half marathon. 

Change your bike expectation to <2:25 and your run expectation to <1:35 and you are still on target.  If everything clicks, then you still have <1:30 run as a possibility.

My FTP is below yours and I recently went <2:30 riding very much within myself on a flat but very windy course with some bad roads in a race for which I was not properly trained and tired from a recent HM.  You really should have higher expectations on the bike, IMO.

I realize that many many people overcook the bike, but with an FTP that high, really I think you are selling yourself short thinking in terms of 2:30 on a flat course if conditions are reasonable.

Mind sharing your FTP?  I'm trying to get a feel for what I should expect at my 70.3 in June, but don't really have a good benchmark.  I'm hoping for a sub-2:30 but am only working with about a 280W FTP on a not so flat course. 

I can toss in another data point since I'm a bit slower.  My last HIM last summer, light rolling hills I did a 2:45 bike leg, 169 watts avg / 178 watts normalized.  My FTP is 235 (3.45w/kg).

Edit: Andrew - I played with analyticcycling.com - estimate you at about 2:30 with a 75% FTP effort and 2:15 with 85%.  That's plugging in your power to my values though, so obviously weight and frontal area are going to differ a bit, plus the course itself.

I wouldn't mind if I had a decent figure to give you, but I think it is around 250.  As for the ride, I haven't analyzed the power file yet, but I was aiming to keep it right around 200, and mostly succeeded -- I spiked a little bit a few times, but never lagged, so average power is low 200s and NP should be close to that.