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Photo above: 4 TriForcers qualify for 70.3 World Championships at Oceanside.  We followed the process!


Here are 6 keys for pacing your Half Ironman.  If you are a beginner or someone who struggles to run to your ability off the bike FOLLOW THE PLAN STRICTLY!   More experienced athletes who have a strong track record of running well off the bike can sometimes get away with “painting outside the lines.”  That’s a privilege to be earned!

(1) Put your bike computer where you can see it.

You want your computer somewhere you can see at a very easy glance without taking your eyes off the road.   Barfly makes good mounts that go on your aerobars.   Or, some between the aerobars drink bottles sell mounts such as the xlab torpdo versa that go in front of the bottle (best) or on top of the bottle (OK).    If your computer is on your wrist or even on your bike stem, chances are that you aren’t going to look at it much.  And if you aren’t looking at it then you aren’t using it for pacing.  Which brings us to our next topic…

(2) Go by feel AND use CAPS to pace your race, not targets.   

The first tool of  pacing we use is feel.  Experienced athletes who have a history of  We do several key workouts to dial in race effort and by race day you should have a strong idea of what “Half Ironman Effort” feels like.   To keep us honest and because our sense of feel can be off on race day due to adrenaline and taper, we also use heart rate or power caps to make sure we stay at a “sane” effort.   This is especially important for beginner athletes or athletes who don’t have a consistent history of running strong off the bike.  Experienced athletes who almost always run well (or if they are willing to take a risk of “blowing up” to get a top finish) can go more by feel and keep an eye on heart rate or power as a sanity check.  (e.g. they should know they can’t ride at olympic distance power).

Here’s an example.  Let’s call this person “Alex”

Let’s say Alex has a threshold power of 200 watts to use a nice round number.  Let’s say further that this athlete has a mixed history of running well off the bike at a 70.3 race.   We know that the very best case scenario for that type of person if they are very well trained is that they can ride around 80-85% of threshold power (170w) on flats, 90-94% (188w) on gradual hills and 95-100% on steeper hills that aren’t too long and maybe they can get away with exceeding their threshold power for maybe up to 30 seconds or so on a steep hill.  However, given this athlete’s mixed history of running well we would rather be slightly conservative.

Here’s what we might tell them.  Watch 3 second power on the bike (it jumps around but it is much smoother than 1 second power).  They might also watch “lap power” (average power since the last time you hit “lap”).  It’s time trialing 101 that you should push faster when the course is slow and go easier when it’s fast:

  • When you are on a flat section-– try to never let your 3 second power show 17x (which is conservative).  You can also hit “lap” as you start a new segment and you don’t want “lap power” to show a number close to 170.  (We’d maybe expect it to be closer to 160, which is 80%)
  • Gradual hills: now you are slowing down to maybe 12-15 mph.  There’s less wind resistance so you want to push while fewer watts are getting “eaten up” by the wind.  Push a little harder BUT ONLY IF IT FEELS SUSTAINABLE ON THE DAY.  Now we say we don’t ever want to see power show 19x and we don’t want lap power too close to 190.  But if you don’t have great legs today (or in the moment), maybe you’re still down in the 170s for your power.  That’s fine– never exceed what feels sustainable.
  • Steep hills: now speed is very slow and wind resistance is minimal so we might go all the way up to threshold power IF IT FEELS SUSTAINABLE.  So, make sure you don’t see 2xx for 3 second power.
  • Downhills:  wind resistance is high at high speeds.  It’s a waste of energy to hammer downhill.    Once you are up to speed, get aero and COAST.  Watch your bike computer and keep coasting as long as speed is high (25-27 mph for most athletes).   You won’t lose much (or any) time compared to the people near you who are hammering but you will be banking valuable rest that will pay off at the end of the bike and during the run.

We might also pace on the run by GPS.   We can use calculators to determine that Alex’s “good case” half IM pace is around 8:05 per mile.    Then we can tell him his GPS should never show 7:xx on a flat section in the first 4 miles or so of the run.  Again, if 8:05 feels unsustainable  for 13.1 mile then he should run slower.  Maybe he needs to start at 8:20.  Once he’s maybe 4 miles into the run then he can stick to whatever feels sustainable on the day.  Then of course as the race gets closer and closer to the finish it should feel quite hard and  painful!


If Alex wanted to sabotage his race, he might ride just under the limits even if it doesn’t feel sustainable.   He might try to be clever and defeat the coach’s system by trying to ride flats right at 179 watts, gradual hills at 189 watts, etc.   NO NO NO!   Those are caps / limits.  Ride to what feels sustainable on the day.  What if you have no idea of what’s sustainable?   That’s a skill called “pacing.”  It’s developed in workouts by paying attention to how hard you are able to go for various intervals and correlating that with the feelings, power and heart rate you see.  It’s developed through experience in key workouts (like 3 x 30 min at HIM effort) and racing.  If you have no sense of pacing your best bet is to stick to more conservative power and HR ranges in racing and see what happens.

(3) Don’t “stick to one pace or power.”  Ride your body’s natural ebbs and flows of energy.

This goes along with push the effort that feels sustainable today.  I personally have ebbs and flows in my energy and power throughout a race.  My power cap on flats might be 240, and let’s say 230ish watts feels good for awhile but I hit a patch where I’m feeling weak at 220 watts.  Well then, I’m not going to push harder when I feel terrible.  Instead I’ll back off.  Then a bit later in the ride I might hit a steep hill and get to sit up or even get out of the saddle at times and use different muscles and my power will be strong and pushing up close to my cap.  That’s great if it feels sustainable.  After some good coasting on the backside of the hill my TTing muscles might be feeling much better and maybe I’m back up at 23x watts and feeling good.   Great!  The let’s say I hit another rough patch.. then I back off to what feels sustainable… and so on.

But if I had pushed and struggled to hold 230 watts when it became a struggle, then there’s a good chance the entire race would have been a downward spiral.

(4) FOLLOW THE PLAN.  Focus on process, not outcome.

Trust that the process will result in the best outcome.  As a coach I’ve reviewed several 100 half Ironman races and I know what works and what doesn’t.  And people who have their “act together” and follow this process are the ones that do best.  The process for half ironman for most athletes is to use their power or heart rate CAPS especially to start the bike and run and to follow their fueling and hydration plans.  That’s it!  If you are strong and fit on the day you’ll be feeling strong and you’ll crush it and come home fast!    On that note…

(5) Never look at average speed or average (or normalized) power during the ride!

This is simply not actionable information and can only serve to mess you up mentally.   In the moment we pace by what feels sustainable (under our caps), NOT whether our averages are what we “hoped.”   Do not even look!

(6) Finally, the later you are in each event, the more you can trust your sense of feel.

Let’s say you are at mile 40 of the bike in a half Ironman and all of a sudden your body just “wants to go.”   Notice I said your body, not your mind.    If your body wants to open it up at that point (i.e.  you are pushing against your caps without trying and feeling great), then go for it!   But remember that  you have to run off the bike– don’t push to the finish like it’s a bike race.  And still keep it sane.  If your FTP is 200, you shouldn’t push 19x on the flats for the last 12 miles!  And of course, continue to follow the rule of backing off if it starts to feel unsustainable later on.  A

And of course, there are more caps at the latter part of the run– push to the best you can sustain!  If your heart rate is 200 beats per minute as you cross the finish line then more power to you!


In conclusion… if you are a beginner or if you struggle to run well off the bike, FOLLOW THE PROCESS ABOVE!   I hate to send that email the day after the race explaining that the reason you blew up and had a bad run was because you didn’t follow pacing directions!    TRUST THE PROCESS!