Educated Guesswork

Sean O'Brien 100K Race Report (2024)

On Saturday 1/27 I ran the Sean O'Brien (SOB) 100K in Southern California. I ran this same race back in 2021 and got my 100K PR, so I knew the course and felt like it was an opportunity to do better. My training had been going well and I was dropping PRs on my local courses, so I was looking forward to a strong race and taking off bunch of time, with an overall target of 12:00 to 12:25, so ~30-50 minutes off of 2021. This did not happen, though I did PR slightly.

It actually turned out to be a bit of a mixed result. On one hand, I finished about 7 minutes faster than last time (more on the "about" later), and much higher up in the standings (8th overall out of a starting field of 96) but all of the improvement was being more efficient at aid stations and I actually was a little over 2 minutes slower in the running part. My working theory is that it was warmer this year, and so times were slower, but this is a bit harder to verify than one might like.

To orient yourself, here is the course and the hill profile. The circles on the course are mile markers, so you start at the far right, go all the way to the left, around the loop counter-clockwise, then backtrack. There's an out-and-back down to Bulldog and then you backtrack to the finish. The circles on the profile are "climb score", Runalyze's estimate of how hard the climb was.

Map Profile

[Screenshots from Runalyze, 2021 data]

Overall Logistics #

I've been doing most of my training with Tailwind and Maurten drink mix, but KH races uses Gu Roctane, which I don't particularly like—especially because races have a tendency to offer the caffeinated version—so I decided to use drop bags extensively. To make this easier to manage I mapped out a regular eating schedule, that targeted 320-360 cal/hr, effectively:

  • 1 500 ml bottle of Maurten 160 drink every hour, with 250ml each 30 min
  • Some mix of Maurten solid and Maurten gel aiming for ~100-200 cal/hr.

I use a 30 minute timer to manage all this, so I have to do something every 30 minutes. I started with Maurten solid and then moved onto a mix of regular gel and the caffeinated gels. This got a little complicated to manage due to Maurten's non-orthogonal lineup: Maurten's solid bar is 225 cal, so effectively I was eating 1/3 bar when the timer went off, which is fine. Ideally I would have just used Maurten 160 gels every hour for 320 cal/hr, but I wanted to take caffeine every 2 hrs after 6 hrs and Maurten's caffeinated gel is only 100 cal, so I decided to aspirationally add a Maurten 100 at the 30 minute mark, though I wasn't sure I could reliably do 360 cal/hr. This mostly worked out, especially once I got past the solid phase.

Everything laid out

To make all this easier I bagged up what I needed for each aid station in a ziploc (with two bags for Kanan, because you hit it twice). The way this works is you get to the AS, you (theoretically) dump out everything from your pack, and then shove in whatever is in the ziplocs in. I labeled the ziploc both with where it was needed and my 2021 time for the AS, so as soon as I picked up the bag I could see if I was ahead or behind schedule. This part worked well and was a lot easier than a pace sheet.

Start to Corral Canyon [7.3 mi, +2270/-846 ft, 1:20:43, -2:25] #

Race start was at 5:30 AM and sunrise at a bit after 7 so I expected to run the first 60-90 minutes in the dark. I got to the start with plenty of time and was able to drop off my drop bags and then just chilled in the car for a while, before heading over to the start line about 10 minutes early, planning to use the bathroom.

This is where things started to go wrong because there was a much longer than expected bathroom line: apparently the portapotties just never got delivered so we just had the park's bathrooms, which really weren't enough for 100 runners. For some reason, the RD decided not to delay the start even though a number of people—including me—were still waiting. I decided that it was better to use the bathroom than to be right at the start, and ended up missing the start by about a minute (not the first time this has happened to me, TBH). I think this was the right decision overall: a minute isn't much for a race this long, and I wasn't expecting to win, but the result is that I started essentially at the back of the race. There are some early sections of single track and so I spent quite a bit of time trying to get past people who were going a lot more slowly than me. It's important to conserve energy early, so I tried not to get too aggro, but it still slows you down.

New for this year there was a real water crossing 2 miles in (I had heard rumors about this but no details because I missed the briefing at the start), where you actually had to wade through almost knee deep water with a rope for stabilization. I'm never a huge fan of this, but it was already fairly warm (never a good sign) and my shoes dry quickly, so it wasn't uncomfortable. Eventually I made it past most of the people slower than me and then things opened up into fire roads so it wasn't a problem to get past people any more. I felt like I was running pretty comfortably, and, as with last time, opted to run as much as I could.

I finally hit Corral Canyon at 1:21, about 3 minutes ahead of 2021 (all times here are from my watch, not gun time), which seemed pretty good considering the start. I was trying to be conscious of aid station time, and was in and out in 1:05. This is about the best you can do if you're drinking regularly and using your own nutrition because you have to pour the powder into the bottles and then add water, but I see now it was 40s slower than last year, so I think that's just the price you pay for bringing your own nutrition.

Kanan Road [6.3 mi, +1010/-1444 ft, 1:06:55, -2:13] #

This next section is mostly rolling single track and fire road. I was feeling reasonably good on this section, but it was a bit hard to get into my rhythm, as there were a lot of rocky sections and stream crossings, and I actually tripped a couple of times, which wasn't great. Fortunately, the dirt was soft, so I didn't get hurt, but it's kind of discouraging. Other than that, this section went reasonably fast.

The first drop bag is at Kanan road, so I was able to grab my nutrition refill and check my time (about 4 minutes ahead) I lost some time here because I'd taped up the bag too much and had trouble untying it and then had to refill my nutrition but still got out reasonably quickly (3:57). Only after I left did I realize I still had my headlamp in my pack, but no way was I going back to drop it off. It's not that heavy, right?

Zuma Edison Ridge 1 [5.4 mi, +1260/-997 ft, 1:00:12, -0:58] #

This next section is a rolling descent on single track followed by a moderate climb on fire road to the top of the ridge line ad. The fire road was pretty smooth and as with last time, I felt good and pretty much ran this whole section. There is a nice moderate descent that was longer than I remembered and a bit rocky but I felt really comfortable on. By this point in 2021 my knee had already started to hurt, but everything was still good, so that felt pretty promising. The next aid station (Bonsall) is all downhill so I chugged some water, refilled my bottle, and just headed out. I forgot to hit my lap timer on this one, but I know that the aid was pretty fast.

Bonsall [3.4 mi, +0/-1706 ft, 26:34, -2:49] #

As noted above, this next section is a 3.4 mile descent down to the Bonsall aid station. Pretty much this whole thing is on fire road so I was able to take it pretty fast (~7:46/mi, 50s/mile faster than 2021). With that said, I was apparently overcompensating for it feeling short before, because I expected it to go really fast, and, well, it kind of didn't; I kept thinking "OK, we must be at the bottom", but I wasn't. On the plus side, I was passing people, which doesn't usually happen for me on the descent, so I was feeling like all that training for downhill was paying off.

I hit the aid station (second drop bag), swapped out my food, and filled my bottles. It was only at this point that it started to sink in that I had nearly 2 hrs of exposed mostly climbing, it was starting to get hot, and I only had two bottles. I compensated by chugging some water and salt caps and crossing my fingers. A while after I left the AS I realized I was still carrying my headlamp, but once again, I wasn't going back.

Zuma Edison Ridge 2 [7.76, +2910,-1184 ft, 1:56:17, +4:43] #

There's a long climb out of Bonsall back to Zuma Edison Ridge. This is actually two climbs, ~1600 ft, followed by a descent of around ~1000 ft and then another climb of ~1300 ft. As I rolled out of the aid station, someone came by me with 3 bottles and one bouncing in his pack and I started to think I had made a serious mistake in terms of fluid but it was too late to fix it.

This section is mostly hiking and there 3-4 people ahead of me, including a guy named Colton who I'd run part of the way with earlier and I'd been sort of going back and forth with (he eventually finished one place behind me). I was able to mostly keep them in sight, but not make much progress. This section is super exposed and I was really starting to feel the heat and actually worried that I wouldn't have enough. I didn't really think it would take me more than two hours (two bottles by my drinking schedule) but in the heat I really needed to be drinking more water than dictated by my calorie needs. Worse yet, my knee started to hurt (same place as last time!) whenever I ran, but as I wasn't doing much running, I just tried to ignore it.

I would say this section was harder than 2021: I felt like it was hotter and I felt like I was struggling more. Partway though the second climb, the eventual first woman passed me and she just looked a lot lighter on her feet, running parts that I only barely had enough energy to hike. So, I was pretty glad to finally get to the Zuma aid station, but this leg was about 5 minutes slower than 2021. I burned through the aid station this time and just kept going.

Kanan Road [5.4 mi, +1037/-1283 ft, 1:03:45, -2:40] #

At this point we're just backtracking down the backbone trail to a previous aid station. This means a ~600ft climb followed by a step descent and some rolling terrain. I started to feel somewhat better here and was trying to focus on moving well on the downhill. At this point, I passed Colton again, for the last time and just kept moving. At this point I figured I was probably around top 15. I made it to Kanan OK, grabbed my next nutrition refill, and finally, remembered to drop my headlamp into my drop bag.

Whatever was wrong with my knee seemed to have fixed itself, so I was less worried about not being able to finish, and I had a pacer meeting me at Bulldog (mile 50), so my approach was just to treat this like a 50 miler and figure the last 12 would take care of themselves. This really meant one more modestly hard segment back to Corral Canyon and then the long downhill to Bulldog which was pretty runnable, so I was really just counting down to Corral Canyon at this point.

Corral Canyon [6.4 mi, +1453/-974 ft, 1:30:55, +1:41] #

We're still retracing our steps back to the first aid station, so this is mostly on single track and generally uphill. There was definitely a fair amount of hiking here, but I was really trying to keep solid running where I could. By this point in the race I was starting to pass people doing the 50K (almost nobody seemed to be doing the 50 mile), which is kind of nice, but I imagine pretty unpleasant for them, given that I was running a lot faster after a lot further in. This part didn't feel that bad, but nevertheless I was glad to hit the aid station, and was looking forward to the long downhill to Bulldog.

Bulldog [5.9 mi, +486/-1946 ft, 1:03:19, -0:07] #

This section is a long out and back, with the aid station being at the bottom. Fortunately, this time I had a better picture of the course and I was prepared for the mile long climb to the downhill, so it wasn't as demoralizing that time. I was almost to the top of the climb when someone came tearing the other way. I asked him if he knew what place he was in and he said first, which was reassuring in terms of where I was at in the standings but also meant I could just count off people going the other way to see where I was.

I tried to push this downhill a bit within the limits of not falling, and felt more in control than last year, though actually the overall pace for this leg was nearly identical to 2021. I was most of the way down before I saw #2, who turned out to be Ian Sharman, who has 9 Western States Top 10 finishes, so I felt like things were going pretty well, even if he was probably having a bad day (I eventually finished around 83 minutes behind him).

Eventually I hit the bottom of the hill and it was onto the flat/rolling section, which I'd remembered as ~1 mile but is actually more like 2 miles. About a mile from the turnaround there is a concrete bridge/overpass over a small river, which you have to get over somehow. It's maybe 3 ft above the trail and someone had put a small stepladder so you could get onto it, but even so it was a bit of a struggle, which wasn't a really good sign in terms of my legs being fresh. By the time I had made it to the aid station, I counted off 6 men and 1 woman before me, which seemed pretty good. I grabbed my last nutrition bag, my headlamp, and headed back out.

Corral Canyon [5.8, +1906/-495 ft, 1:32:06, +6:42] #

My pacer Kate and I ran the flat mile or two modestly hard—the bridge was even worse on the way back because I sort of had to scoot down the two whole feet onto the ladder—and then just settled in for the long hike up to the top. I was trying to push this pretty hard but definitely wasn't feeling amazing. Still, it was pretty nice to see everyone behind me going the other direction.

I'd hoped to make up time on this segment, but actually I was almost 7 minutes down for this leg (still about 8 minutes ahead overall) by the time I hit the aid station. I actually thought I was more like 14 minutes ahead because I misremembered my target time (note to self: also do a pace sheet). It didn't really matter, though, because my plan was just to push the pace as much as I could on the way down.

Finish [7.3 mi, +833/-2277 ft, 1:27:27, +0:30] #

The way to the finish is some rolling single track followed by a really long descent, first on fire roads (remember, we're backtracking again, though I'd done this section entirely in the dark on the way out) and then on single track. At this point, I was hiking most of the climbs but trying to run the downhill as much as I could.

Unfortunately, due to the shorter day and the later start, I had to run a lot of this in the dark, unlike 2021, when I finished in the light. I did have a headlamp (Petzl Actik Core), but I was really wishing I had something brighter, especially when we got the single track. If I'd just carried my Lupine another 10 miles or so, I could have had it with me for this, which might have made a difference, as I wasn't able to go as fast as my legs would have supported because I couldn't see very well

After a long downhill there is a mile or so of uphill, which I knew about this time (pretty much right after the water crossing) and was actually looking forward to, both as a break from having to pick my way through things and an opportunity to push the pace some. I did that and was rewarded by getting to listen to Kate breathing a bit harder behind me. This felt a little longer than I expected, but I'd been doing plenty of climbing in training so I was comfortable with it.

After the peak of the hill, it's back to the single track descent followed by about a half mile of nice flat fire road, which gave me an opportunity to open up a little bit towards the finish. We were still passing people but they were not in the 100K so it doesn't really count.

Analysis #

As I mentioned at the top, it's hard to compare year to year, so this section is mostly me thrashing around trying to get a better sense of it. The chart below shows my performance against 2021 (watch time, not gun time):

Leg Distance Vert Time vs 2021 vs 2021 (cum)
Corral 7.29 mi 2,270/-846 ft +1:20:43 -2:25 -2:25
Aid - - 1:05 +41 -1:44
Kanan 6.34 mi +1,010/-1,444 ft +1:06:55 -2:13 -3:57
Aid - - 2:37 -1:20 -5:17
Zuma 5.42 mi +1,260/-997 ft 1:00:12 -58 -6:15
Bonsall 3.43 mi +0/-1,706 ft 26:34 -2:49 -9:04
Aid - - +2:56 -1:30 -10:34
Zuma 7.76 mi +2,910/-1,184 ft 1:56:17 +4:43 -5:51
Aid - - 2:05 -3:22 -9:13
Kanan 5.40 mi +1,037/-1,283 ft 1:03:45 -2:40 -11:53
Aid - - 3:26 +23 -11:30
Corral 6.37 mi +1,453/-974 ft 1:30:55 +1:41 -9:49
Aid - - ? -2:13 -12:02
Bulldog 5.91 mi +486/-1,946 ft 1:03:19 -7 -12:09
Aid - - 3:22 -29 -12:38
Corral 5.84 mi +1,906/-495 ft 1:32:06 +6:42 -5:56
Aid - - 1:51 -2:11 -8:07
Finish 7.32 mi +833/-2,277 ft 1:27:27 +30 -7:37

As seems pretty clear here, I was just faster through Bonsall both on the running legs and in the aid stations, and then I lost a lot of time on the climb out of Bonsall and then again on the climb out of Bulldog, but was still about the same as 2021 on the rest of the legs and was better on the aid throughout.

The graph below compares my paces on each grade from 2021 to this year with one graph for each hour.

Speed versus pace

Speed versus grade, faceted by hour.

For the first 5 hours, I was just plain faster both on the climbs and the descents. In hours 5 and 6 (the climb out of Bonsall) I started to slow down, especially on the climbs. I recovered again on 7 and 8 when it was just straight running, and then struggled again on the climb out of Bulldog but was pretty solid towards the finish.

It's a bit hard to know exactly what to make of this, but my working theory was that it was hotter this year and so when I had to exert a lot of effort on the climbs, I slowed down but when I was able to just run comfortably, I was still faster because heat wasn't as much of a factor. It's of course possible I have gotten worse at climbing or I wasn't pushing as hard, but I don't think that's true. I was definitely pushing pretty hard on the climb out of Bonsall and I felt like I was pushing on the climb out of Bulldog and that was Kate's impression as well. I've generally been hiking pretty well this season, and as noted above, I was doing well on the climbs early in the race, so I don't think I've just suddenly gotten a lot worse in this area.

Beyond my own performance, there are some other reasons that suggest that this year was harder and that it was at least in part due to heat:

  • Runalyze's estimate of the weather is 72o this year versus 63o for 2021 (though more humid in 2021) and Garmin's somewhat confusing sensor (which seems to integrate skin and air) also shows things 5-10o hotter in 2024.
  • The drop rate in 2021 was 3/33 (9%), whereas this year it was 23/96 (23.9%)
  • In 2021 there were 5 people under 12:00 and this year there were 4 even with a much larger field.
  • While Kate was waiting at the aid station, she kept hearing how people were underperforming because it was hot.
  • While the winner's time was the same, the median times were a lot worse (~28 minutes overall, 67 minutes including DNFs), as shown below:
Year Notes Mean Time Median Median excl DNFs DNF rate
2024 Same as 2021, 2020 course 14:45:48 15:29:40 15:08:40 23/96 (24%)
2023 Short course (~2-3 miles) 13:44:00 14:04:51 13:42:59 4/94 (4%)
2022 Short course (~3-4 miles): reroute due to rockslide 13:37:04 14:01:46 13:45:56 7/69 (10%)
2021 In October instead of January 14:04:24 15:01:14 14:21:13 3/33 (9%)
2020 13:41:24 14:11:57 13:43:33 24/154 (16%)
2018 13:43:56 14:09:24 14:09:24 131 finishers, no DNFs listed
2017 Short course due to weather (~2 miles) 12:44:49 12:46:20 12:46:20 137 finishers, no DNFs listed
Figure thanks to Kate Hudson

It may also be the case that I and others aren't as heat adapted because the race was in the winter rather than the fall.

I do think I faded a bit in the last 13 miles or so. I don't have splits, but I estimated that the female winner was maybe 1-1.5 miles ahead of me at Bulldog and she finished 45 minutes ahead, so she must have put at least 20 minutes on me from there. That's consistent with how fresh she looked when I saw her earlier: I definitely think those miles would have been a lot faster if I had been fresh and running more than hiking (they would also have been faster in the light!).

Retrospective #

Times, aside I felt like I followed the game plan pretty well. I ran when I could and hiked when I felt like I had to. I think there were maybe a few places towards the end that I could have run if I had to, specifically the up part of the rollers at the beginning of Bulldog and after Corral Canyon, but I felt like I was hiking pretty fast, so I'm not sure I would have run it much faster; I think I was in part just limited by what I had left in the tank. I'm quite pleased that I was legit faster on the downhills most of the race. This is something I was working on and so it's nice to see that pay off. I'm not sure why I kept tripping, but I guess I still have more agility work to do.

Missing the start really sucked because of having to work my way through everyone. I think this was the right decision, as I definitely had to go and made it through the race without issue but I wish I'd made it to the toilets earlier, so I could have started with everyone else. I might have pushed a bit too hard at the start, but I think I did a reasonable job of holding back.

My nutrition strategy worked well. It was pretty easy to stick to an every 30 minutes schedule and I didn't have any major GI issues: I felt fine until after Corral Canyon and then just a little nauseated afterwards, and even then I was still able to eat, just not as many calories per hour as I wanted (mostly I ditched the extra Maurten 100 in the hour when I had caffeine.). Having a caffeinated gel on the half hour was easy to manage. The two things I might change here are:

  1. I want to try to just do 360 cal/hr, so I could do a Maurten every 30 minutes
  2. I should have brought an extra bottle for the Bonsall climb and just had electrolyte or swapped out another Maurten 160 bottle for a gel, because I think I did get dehydrated there.

As noted above, I wish I'd had a better light for the finish. I think I got optimistic because I finished in the light in 2021 and didn't properly account for the later start and earlier sunset.

Overall #

12:46:25 (gun time), 12:45:37 (hand time). 8th/73 overall, 7th/59 (male), 1st 50-59

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