marathon pace vs 13.1 HIM pace

I would say I'm close.  Did my first HIM at 8:37 pace, and did my 3rd marathon later that year in about 8:50 pace.  I was shooting for 8:20's in that marathon but I wasn't feeling as good as I hoped to on race morning.

How close you get to your open marathon time will likely depend on your bike fitness and bike pacing.

You really have to be very careful how you compare the two from several angles.

First, the two races have to be very closely spaced, kind of difficult if you need two weeks to recover fully from each. Running races tend to start early in the day, cooler temps and most of the time less wind. Finally, the topography of the two also matters, apples to apples.

The other issues you need to cover is accomplishing the proper amount and race specific training for each, hitting proper volume, proper intensity, the length of intervals........

In the real world of practical prep for races, we tend to use a distance for say determining the VDOT number, than we go across looking for equivalent race performance at the distance desired.

It is a very close approximation to say that HM to HIM split is 5-10min range depending on:

1. Bike fitness

2. Bike execution (pacing/ effort)

3. Bike hydration/ nutrition

4. Run fitness (accomplishing all run training and appropriate amount of MP running within)

5. early run pacing, going out too fast first 3mi........pretty common in races

Hope this points you in a direction to research more.

You sir, are a beast! Enjoying your race reports.

As I said I've come a long way in just a year and a half of actual training. Only the last 3 months have been riding also. With 61 days left most training will be spent getting comfortable with riding distance at comfortable pace. I'm stubborn and like to push until I'm out of gas. Not the greatest game plan in any endurance race. However my Oly series I recently completed really put things into perspective for me and I realize I need to work a lot on my bike pace.

My HM pace is about 30s/mi faster than my full mary pace.  7:13/mi for the HM and 7:45 for the mary.

Put your numbers in the McMcillan calculator.  it'll give you the answer... provide  you have the volume to support the predicted marathon pace.  

then- adjust for temperature, altitude, and elevation change.

I will search for the link but I found a calculator online (I believe it was linked from the Google Wattage group) that used 3 different methods (the only one I remember was an EN version) to estimate your HIM run pace based on a VDOT or other testing method. It was amazingly close to the strategy I had planned out prior based on my training. If I remember correctly the HIM pace was about 5-10% slower than Marathon pace.

If I can find the original link I will add it here, if not PM me and I can send you the original file.

I have a post on my blog about run pacing for triathlon- take a look here.

You can use the table to figure out pacing for different events given your known pace on a few events- net net, this work suggests that half iron run times and open marathon times are quite close together...

This fits well with the other file I referenced above. I also agree with your blog post - scary how well this seems to fit with align with real world testing (once bike pacing is dialed in)

x2

Marathon 3:32, HIM 1:49.  I was trying for an 8:00/mi in both events.  In both events, I broke down towards the last few miles.