My Leadville 100 Fueling Strategy

This is the fourth part in my Leadville Blog Series. Earlier posts available here. This one is longer than the prior entries at nearly 5,000 words and about a 20-minute read. I made a real effort to cut it down, but this was as tight as I could make it without losing substance. My hope is that the signal-to-noise ratio is high and it will be a worthwhile read.

How to Plan for Leadville Fueling

When I started riding again seriously (see my original post for more on my background) I still assumed I would just need to pack two bottles, some snickers bars, and Haribo for my long rides. I’d heard about these magical high carb mixes but figured it was just alchemy like ketones were a decade or so ago (I never found ketones to be useful for me). I did a few hours in early March on no breakfast, a banana, and a chocolate milk and bonked hard. I decided maybe it was time to give carbs a try. I did and they were foundational to my success.

What I want to do here is detail how I planned a fuel strategy for Leadville - what I used, how I planned, feed zones, and more. This is just my experience with fueling and I think that it worked extremely well. For avoidance of doubt these are my opinions and interpretation of the science. Not facts: DYODD.

My Fuel Choices

There are a lot of products out there, and different products will be good for different people based on metabolism, preferences, etc. I experimented with Maurten products, Skratch Ultra High Carb, and SIS products. Ultimately I have decided to use (almost exclusively) Maurten products. I like the taste, consistency, I don't fatigue on the flavor, my gut can handle them really well, and I like that I can easily mix in a Nuun/LMNT/Precision Hydration packet as needed.

I can't emphasize enough you need to experiment to find what works for you.

For Leadville my quiver of fuel products was as follows:

• Maurten 320: 80g carbs + 245mg sodium
• Maurten 320 CAF: 80g carbs + 245mg sodium
  • Includes 100mg of caffeine
• Maurten 160 Gel: 40g carbs + 30mg sodium
• Gu Espresso Love: 23g carbs + 60mg sodium
  • Gu is a nostalgia product for me - my college rowing team had a Gu Pro Team deal and Espresso Love was my favorite gel flavor from them. I wanted something that was different in case I got flavor fatigue and I did end up consuming two Gu gels during the race.
  • Includes 40mg caffeine
• Precision Hydration 1000: 500mg sodium and about 16g carbs
  • These carbs count for fueling but they're not a primary source of fuel
• My crew had a bunch of the following but I didn't end up taking any of this:
  • Haribo Gummy Bears
  • Coca Cola (opened the night before so it was flat)
  • Uncrustables (if you know, you know)

How to Plan

This is what my spreadsheet looked like. A lot of trial and error was involved with this but I swear that there was a method to the madness at the end of the day despite how messy this screenshot looks.

Planning at a high level can be quite simple: how long do I expect to be on the bike and what nutrients per hour do I need based on that? It gets more complex when you factor in other variables - how often can I refuel, how many carbs can I carry at any given time, how much sodium do I need early vs. late, and more.

Fuel planning is just rate * time, repeated feed-to-feed: set your hourly carbs/sodium/fluid targets, multiply by each segment duration, then choose bottles first and gels second to hit the number without exceeding what you can carry.

My inputs for fuel planning were as follows.

Pro rata distribution of everything

I didn't get cute with it. I assumed every hour had the same fuel needs even though in reality I might need fewer carbs/sodium in the cooler morning and more in the warmer afternoon. My goal was just to target the same every hour.

120g/carbs per hour target

I won't spend any time here on why carbs are the unit we plan around on the bike vs. calories. I think this is generally well understood enough now but this is one concept ChatGPT does in fact get right at a high level if you ask for an ELI5.

My gut can handle something like 120-140g per hour. If you're reading this and don't understand what I mean by what "my gut can handle", read this first. So the Carb Hourly Needs portion of the planning formula I treated as a constant of 120g throughout the whole day.

If you're wondering how to pick a carb target, read more here.

750mg plus of Sodium an hour

I'm going to spend more time on sodium / hydration than carbs.

The hydration plan should revolve around sodium

For a one-day race sodium is the only electrolyte I planned tightly because it’s the one we lose in meaningful amounts in sweat and the one most tied to fluid balance in-race. Other minerals like potassium, calcium, and magnesium losses in a one-day event are small and tightly regulated by the body so they don’t limit performance in-race. Sodium is lost in the greatest amount from sweat and most directly impacts hydration and performance. Failing to replace others in hours/days after can impair recovery and performance in subsequent efforts (i.e. training days or in a stage race) so be aware of this (but sodium is the key).

Know your sweat profile

You should understand your sweat profile. Precision has more information on this idea and a qualitative calculator if you don't want to do a full sweat test. I am a medium salty sweater so I targeted 750mg / hour of sodium during the race. My Sodium Hourly Needs I treated as a constant of 750mg in my calculations.

Pick your Products

I use Precision Hydration 1000 specifically . I experimented with a few different products over time. Mixing an LMNT into bottles, table salt, salt tabs, and other products. I chose Precision because its designed for endurance athletes (that means its sodium concentration is ~3x off the shelf sports drinks or mixes like LMNT) and does contain potassium, magnesium, calcium in smaller quantities.

Sodium really matters!

Sodium planning was a new concept to me for Leadville. I used to throw a Nuun in a bottle and call it a day (this probably doesn't surprise anyone based on how I thought fueling should work). I bonked hard while far from home during a hot training ride in June despite plenty of carbs. I learned a sodium bonk is possible and feels very similar to a hunger bonk and got more serious about hydration.

Note that the PH 1000 also has 16 grams of carbs per packet.

2 bottles for 1500 ml total per segment

My bike can fit two bottles, one 600ml and one 900ml bottle. Maurten recommends a 320 takes 500ml. I am comfortable with 1.5x320 in the 600ml bottle and 2.0 * 320 in the larger 900ml bottle. This gave me an upper limit for how much I could carry in bottles as 280g total at any given time. Each Maurten also has 245mg of sodium per packet (on top of my Precision Hydration).

I did not want to carry a bladder on my back. I didn't need one which is hopefully evident through this post, but I did pack one in case I was feeling crappy and wanted to have some plain, cold water to spray on myself or drink. If you aren't using a crew (see more on that below) I do think a pack is probably useful.

~750ml of fluid an hour

This was more art. I can get by with about 500ml per hour up to around 70 degrees and need up to 1L in hot. Fluid needs at Leadville are driven by sweat and respiratory losses at altitude. Planning for ~500–750ml/hr gave me enough margin to stay ahead of dehydration without forcing fluid or overwhelming my gut, especially early when thirst cues can be misleading at altitude. This was also somewhat driven by necessity as I didn't want to carry a pack and only could carry 1.5L on the bike frame so I had to get by with ~750ml/hour.

Gels gave me an extra 40g of carbs

I used Maurten 160 gels which gave me 40 grams of carbs per gel with another 30mg of sodium. I also used a couple of Gu gels which gave me 23g of carbs per with 60mg of sodium. The Maurten gels are hard for me to get down but I like staying consistent on the brand and I do like the plain flavor of their gels.

Caffeine dosed appropriately

I consumed a generous amount of coffee pre-race for the obvious reasons and then planned to take caffeine a few times throughout. Small shots in the Gu gels and then twice via a Maurten 320 + 100 CAF (100mg of caffeine). I didn't specifically plan this out because I'm not particularly sensitive to caffeine but I do drink a ton of coffee and wanted the caffeine drip going through the day. If you are more sensitive to caffeine you should definitely plan specific doses. I made sure mine Maurten CAF mixes came before Columbine and before Powerline inbound.

Plan for the goal, pack more

My goal was to go sub-9 hours, so I planned as if I'd be on the bike for 9. Based on this I calculated based on historical finishers I calculated.

Total Carbs = Hourly Carb Needs * Max Finish Hours

Total Sodium = Hourly Sodium Needs * Max Finish Hours

My total carbs were therefore 1,080g for the full day (at 9 hours) and 6,750mg of sodium. I used this as a check function to confirm I was planning enough.

I also was sure to carry 3 additional Maurten 160 gels (120g of carbs total) in the event that I was on the bike for closer to 10 hours or I dropped a bottle. My crew also had several extra gels on them in case I had multiple dropped bottles, etc. Leadville also offers neutral service I could have used if necessary.

How this came together

At the end of the day this is more of an art than a science. The science is above. What follows is the art, answering questions like "do I want super-concentrated bottles as it gets warm or late in the day" or "can I easily take gels on this segment" or "what happens if I drop a bottle or get flavor fatigue". And of course the big one "how to I translate my carb & sodium needs into a plan".

My approach to this was something like this:

• Use bottles first
  • In my last big ride I suffered big time on a ~75 minute climb up to Gold Hill with super-concentrated bottles and was really hurting for plain water. I didn't want to carry plain water, but I did want to keep the concentration less viscous just in case the worst happened in race.
  • I therefore figured I'd put one 320 and 1 PH 1000 in each bottle to start
• Fill the gap with gels
  • With the above in bottles, what did I need to gels to make up the delta?
  • I was able to make this work no problem
• Concentrate bottles if a reasonable number of gels wasn't enough
  • If necessary, I could add more to bottles up to my limit (I didn't need to)
• Use total needs as a check and triage as necessary

You can totally do what is best for you here. Want more bottles with water and sodium and carbs in a pack - great, goal seek for that. Want gels first carb mix second, great, goal seek for that. It is totally your call, you know you best!

The Plan

Here is what the fuel totals I needed looked like.

I planned for four total stops which gave me ~2.5 hours at most between feeds. I randomly selected 10 or so different finisher times from 8:30 to 9:15 to approximate when I'd arrive at each feed and I think this is the right approach. Figure out the range of possible arrival times, pick the midpoint. I'll talk more about feed zone selection below (I would do this different next time). I then went through the exercise (manually) of plugging numbers into my bottle and gel counts using the goal carbs per segment and knowledge of carbs/sodium in each product I was using. This was in effect a manual goal seek to get to a total that was in line with need for the segment. For the math inclined I took my hourly needs as defined above and distributed these totals across segments using the following formula:

That looked something like this for me:

You'll probably notice I have 140g planned per hour in the first segment. I planned to and did take one of these just before the start. Since I can tolerate this many carbs I wanted to get off to a strong start for the day.

I only needed to put a single 320 in each bottle (plus a PH meant 96g carbs total for each bottle) and gels were easily able to fill the gap for the target need per hour. Both my carb needs and sodium target was hit almost dead on. I did mix in 320 + 100 CAF twice once for Columbine and again for the final push to the finish (this is just a Maurten 320 with 100mg of caffeine in it) as I mentioned.

Plan vs. Actual analysis

So, what actually happened on race day?

I didn't get anywhere close to consuming 120g / hour. My actual carb intake ended up being ~90g / hour¹. I was quite shocked at this initially after the race. At most I consumed 120g / hour early in the day. Later in the day I was only taking in a little more than 60 grams per hour, well under target for the race.

Here is how my intake actually looked vs. plan:

What this shows is the approximate carbs remaining each segment and the segment delta (vs. plan) as well as the total delta vs. plan. I was consistently about 20% under my carb plan. I was nearly 50% light in the last 2 or so hours. And my guess is that it was even worse than that because I frantically sucked down carbs from my bottles in the last 30-40 minutes as I started to bonk.

My biggest learning here is that I can tolerate very high carbs on easier solo rides without much complex terrain but at Leadville intensity + altitude + technical sections + traffic, the real limiter was finding time, not gut capacity. I think this will be true of everyone, its hard to remember and find time to eat and harder to match that with places where eating is feasible given terrain.

¹ The evening of the race I took stock of how many ml were remaining in each bottle and noted where I didn't take gels so I could do this retrospective

Honest Thoughts on Plan vs. Actuals

Besides it being hard to eat I felt like I followed the plan well... except...

Fear of gut issues and overconfidence got the best of my race-brain.

I started to feel a little ill after descending Sugarloaf inbound and before the Carter Summit climb. If you've trained and raced with carbs you know the feeling when you get a bit burpy and bloated and your stomach starts to tell you things. Not taking enough sodium can also create a similar bonk feeling. At that time I needed to be smashing my fuel for the final push up Carter Summit to the finish but I got nervous about my gut. As a result I clearly under-fueled and by the time I got off the St. Kevin's descent I could feel the bonk beginning to come on.

With some honest reflection I can also say that I got a little too confident in the last 2 hours. I had a really hard time on the stretch from Twin Lakes to Outward Bound inbound but I'd fueled well and seeing my family reset me mentally for the final push. I all of the sudden felt like I had a lot left in the tank. I felt awesome up Powerline and was pushing above pace on the Carter Summit climb. But I lost discipline on fueling in the last 2 hours especially as I increased pace/power.

When I started to feel not great I figured I'd make it to the end before really bonking but at that point in the day I was just barely keeping the tank full and I feel off more quickly than I expected. It is hard to tell if there is anything I could have done differently here or if it really made a huge difference though. Given that it was late in the day and there was no big climbs left I'm not sure that this fueling mistake cost me more than a few minutes. Plus it was the end of a 9-hour race - I wasn't supposed to feel good. The data is clear though. I under-fueled by nearly 50% and that absolutely made a difference.

Failure Modes

There are a few failure modes I've danced around but I want to explicitly call out:

• Dropped bottle → what’s the minimum you can survive on to next aid?
  • I took enough extra gels to make sure I'd get through
  • My crew had even more gels just in case + other treats/snacks
• Too cold early → you don’t drink → you under-fuel → later GI weirdness
  • Set Garmin reminders to drink and practice drinking on rocky climbs
  • A pack isn't ideal but its easier to sip from for sure
  • Leadville is an eating contest: if you don't eat you'll suffer
• Too concentrated bottle + no chase water → gut stalls
  • I went lighter on mix and made up for rest with gels
  • There are on-course service where you can get plain water
• Final hours “I feel great” → stop eating → classic late bonk
  • I talked about this already since I fell into the trap

Leadville Specific Considerations

It is hard to eat as much at altitude. Appetite is suppressed, digestion slows down, and blood flow is prioritized to working muscles over the gut, especially on long climbs at high effort. Practically, this means gels are harder to get down, concentrated bottles sit heavier in the stomach, and it’s easier to subconsciously skip calories even when the plan says you shouldn’t. This showed up clearly for me late in the race and my intake dropped when it really mattered most.

I recall hearing a pro (maybe Keegan) talking about this and his fueling after the race and it was under his target as well. If someone knows what I'm talking about send it to me (sean@racepace.cc) and I'll add the link as an edit to this post.

I don't think this means the plan should change, but recognize that its OK and probably expected to come in well under what you plan for fuel for the day.

Raceday Logistics

Where, How, and What Eat

Do you want to be reaching for a gel while tangling bars with folks up St. Kevins? Trying to open a gel while riding up the sustained 20%+ grade on Powerline Inbound? Probably not. Each part of the course has some areas its easy to fuel, some where its hard to fuel, and some where bottles vs. gels are needed.

1. Start to Outward Bound
   1. Bottles: should represent most of your fuel
   2. Gels: two places to easily take gels
      1. Bottom of the Carter Summit road decent (Turquoise Lake Road) before the turn off Hagerman Pass Road (paved road / wide dirt road) gives plenty of opportunity and space for gels
      2. Bottom of Powerline Descent to Pipeline (paved road)
   3. Notes: plan to have a hard time drinking and eating given crowds on St. Kevin's and on the climb up Sugarloaf (the backside of Powerline); if you're a nervous drinker you should absolutely practice this
2. Outward Bound to Twin Lakes
   1. Bottles: anywhere
   2. Gels: pretty much anywhere
   3. Notes: rolling, with extended paved sections make this prime time for smashing fuel before climbing Columbine and staying on fuel plan
3. Twin Lakes to Twin Lakes
   1. You simply CAN NOT plan to eat once you get to the Goal Trail outside of stopping at the top or sucking down a gel before descending. It's rocky, crowded, and narrow with traffic coming downhill on your left. Be aware of this and take what you need before you hit the final bits of the climb up Columbine so you're fueled for climb + descent as well. You can certainly try to eat, its not against the rules, but its difficult IMO.
   2. Otherwise:
      1. Bottles: pretty much anywhere pre-Goat Trail
      2. Gels: easiest anywhere before Columbine climb, possible on most of the climb pre-Goat Trail if you are able to stay heads up for descending traffic and climb steeper punches one-handed
4. Twin Lakes to Outward Bound
   1. Bottles: anywhere
   2. Gels: pretty much anywhere
   3. Notes: rolling, with extended paved sections make this prime time for smashing carbs and playing catchup if you need to before Powerline
5. Outward Bound to Finish
   1. Bottles: anywhere except steep parts of Powerline
   2. Gels: similar to section 1 in reverse, there are good spots but plan to be ver fatigued on most of the climbs so bottles will be easiest in general
   3. Notes: there is a 5-10 minute paved road section after the feed before hitting Powerline, this is prime time for smashing food; after descending off Sugarloaf you hit the paved road back up Carter Summit and this is a terrific spot to smash gels and carbs (the opposite of what I did)

What about if I use Pipeline Alternate and/or Lost Canyon Road (Twin Lakes Alternate) for feeds? This doesn't change too much in my opinion. For the former you will have a longer stretch of flat after descending Powerline, less time in between your first feed and Twin Lakes, and for the latter you have less time after getting your feed before hitting the road up Columbine so keep this in mind.

Bottle Prep

I debated putting this in because it seems obvious. You need to prepare your bottles ahead of time, your feed bags ahead of time, etc. There is no time on race day. So the evening before make sure that you have everything dialed in. Measure, label, and have everything clearly identified for your crew (see below).

Feed Zones

We covered this above. Leadville / Lifetime make it very clear where these are. The hard part is figuring out when you get to each one. Conveniently they each are time checkpoint so as I detailed my methodology was to look at so look at historical finisher data and figure out roughly when I'd arrive at each stop.

The feed zones are all listed here.

I stopped at Outward Bound and in hindsight I'd use Pipeline Alternate vs. Outward Bound. If you can choose where your crew stands, Pipeline Alternate is calmer and easier to execute. The Outward Bound feed is chaotic bumpy grass and its a curving part of course. The Pipeline Alternate is smoother double track, more spread out, and straight. It was hard to drink/eat right away Outward Bound over the rough grass single track and it was fairly chaotic on the exit as well. If I used Pipeline Alternate I'd also use Lost Canyon so it was still ~1 hour between.

Make sure you understand times & distances for whichever locations you choose and reflect that i your calculations for fueling for each segment as well.

Crew Support

I have been asked: do I need a crew?

The answer is yes. But look, if you can't realistically afford to bring out 1-2 people or don't have someone who can you will be fine plenty of people don't have a crew and I'm sure there are some who go sub-9 and faster. My wife was not about to let me spend a week in Colorado without her and our 11 month old so that solved that (nor would I have wanted to be alone either).

If you are able to have 1-2 people crew you, do it. It is a significant advantage. There are also coaching services that probably offer support here and/or find some others who are training for Leadville and pool resources with them to make it work. The alternative is drop bags and fewer stops. I didn't do this so I can't offer much insight besides I heard to plan for 10 minutes per feed bag pickup.

I didn't get fancy with my crew stops. I unclipped one foot, dropped my bottles and empty gel wrappers on the ground (my crew cleaned up) and took new bottles and pocketed additional gels. It took at most 15 seconds per stop.

Over-communicate crew responsibility

I didn't go so far as to plan bottle hot swaps at feeds, I stopped and took what I needed. But I did label every bottle, tape on gels to bottles, etc. This was an essentially foolproof way to be sure I got what I needed when I needed it. I also was non-stop reminding/quizzing my crew on what they needed to do when. I would't recommend this but it drove the urgency in nailing feeds home.

Plan where to be

There are two pieces: when to be at which stop and where to stand.

Unless you have a crew that are themselves big cyclists and get it, you need to be very specific. The day before the race we drove to each feed and discussed where they'd stand (on the right side, near the end of the feed zone) and when to expect me. Do not tell your crew "2 hours in or so" translate your race start time (6:42:30 for me) to a clock time. For example, I planned for 1:40-2:10 for arrival at the first feed. This meant telling them between 8:22-8:52am arrival.

Also for the love of god, please feed on the right side for feeds. Yes, you can be on either side, but it was wildly chaotic as people were darting all over feed zones. Be predictable, feed on the right side of the road outbound and inbound. That means that your crew will need to switch the side of the road they're on.

Final Thoughts

I don't think the approach changes too much if you have a longer (or shorter) goal time. The logic for fueling remains the same, although you may have to make compromises to carry what you need if you're still limited to 4 stops. Again, this is waht worked for me ad what my experience was - so don't take it as more.

What I'd do differently

Not a lot other than feeds! But one very big thing RE: fueling per the above.

Everything went really well with fueling otherwise in large part because I treated nutrition as seriously as I treated the on bike prep. Every ride over 90 minutes I experimented with fuel (especially longer rides) and I made a point to push carb intake as high as I could for experiments sake to test my personal limits. My fuel execution was almost better than my pacing (next post) except for one thing.

Other things on my mind

• If you mess up nutrition you're cooked. Full stop.
• Maurten, Precision, etc. aren't cheap products and people will often make their own. Before a national championship rowing race as a high school kid I was budgeting my cash for food during the trip. My coach rightly said, "You spent all the time and money to prepare and get here, why cheap out now". He was right - if you're going to put hours into training why cut corners on nutrition. I'm sure your homebrew works great for you but personally I like the peace of mind / certainty that I get from products I buy at any price.
• Plan for the worst, race for the best for nutrition needs. I planned to go sub-9 but carried enough fuel such that I had 10-11 hours of carbs if needed.
• Everyone starts fast based on the data. When I looked at historical finisher times from 8:15-10 hours the spread at early checkpoints was not huge. I'll talk more about this in another post but I suspect fueling plays a role. Don't get overconfident at any point and stop fueling because you feel good.
• On-course nutrition is available and can help if you drop a bottle or run low. I'm not sure that I'd plan on this to get me through the whole race. I'd also make sure I tested these products before hand just in case.

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