How to Pace a Friend Through a 100-Miler

Your job is not to run. Your job is to keep your runner moving, fed, lit and safe, and to absorb every decision they are no longer capable of making. That is the whole role, and it is why temperament matters more than speed. Before anything else, read the race's pacer rules, because the two things people get wrong are both rulebook problems: where pacing is allowed to begin, and whether you are permitted to carry anything for your runner. Pacer start points vary widely, commonly somewhere around halfway but not always, and muling is explicitly a disqualification at some races and completely fine at others. After the rules, the job is three clocks (fuel, time, motion), one night-kit checklist, and one conversation you need to have before the race rather than at mile 78.

Read the rules first

Every 100-miler publishes pacer rules, and they are not interchangeable between races. Find and confirm these before you commit:

• Where pacing starts. Many races open pacing at a specific aid station or mileage; some allow it only after dark; some do not permit pacers at all.
• Whether pacers must register, sign a waiver, check in, and wear a bib.
• Muling policy. Carrying your runner's water, food or gear is banned at some races and permitted at others, and the penalty at the strict ones can be disqualification for your runner. Do not guess, and do not rely on what a friend told you about a different race.
• How many pacers may accompany the runner at once. One at a time is the near-universal answer.
• Whether pacers may take food and drink at aid stations. Some races feed pacers; some ask you to be entirely self-sufficient. Assume the second and be pleasantly surprised.
• Course rules that now apply to you: no cutting switchbacks, no outside aid away from stations, pack out your own trash, yield to runners still racing.

If anything is ambiguous, email the race director. A one-line answer in writing is worth more than an assumption at mile 62.

Are you the right person for this segment?

Look honestly at the segment you have been asked to cover. Twenty-five miles at a runner's late-race pace sounds easy and is not: you will start cold, in the dark, on unfamiliar trail, at a pace slow enough to be biomechanically awkward, for six to nine hours, with no adrenaline of your own. A reasonable fitness bar is that you could cover the distance comfortably as a training day and still be pleasant company at the end of it.

Temperament is the real qualification. The best pacers are calm, relentlessly practical and immune to being snapped at. If you need to be thanked, or you tend to get competitive, this is not your job.

Study the course either way. Download the GPX, know where the aid stations are, know the climbs, and know the cutoffs. You are the navigation system now.

The pre-race briefing

Have this conversation days before the race, not at the handoff. Write the answers down.

• What do you want me to do when you say you are quitting?
• Do you want conversation, or silence?
• What are your fueling targets, and what can you not stand the taste of?
• What are your known problems: feet, stomach, knees, sleepiness?
• Any medical information I should have: allergies, asthma, medication, conditions?
• What is your actual finish goal, and what is your fallback goal?

Then collect the logistics: crew phone numbers, the aid-station schedule with cutoffs, the runner's bib number, where you will meet, and the plan if they arrive two hours later than expected. Make yourself a cutoff card for your segment, on paper, in a pocket.

The pacer's kit

Assume you are carrying everything you need and getting nothing from the race. That means a vest, not a handheld. A 10 to 12 litre vest like the Nevo Rhino 12L is the right size if you will be carrying spares and a warm layer for a long night segment; if the race forbids muling and you are only carrying your own kit for a shorter leg, a simpler zip-pocket vest such as the RKV86 does the job for much less money.

In it:

• Two headlamps. A bright primary such as the Petzl Actik Core, which runs a rechargeable battery pack with a fallback to AAA cells depending on version, plus a small backup like the roughly 45-gram Nitecore NU25 that lives in a pocket and never comes out unless something fails. The reasoning behind beam patterns and burn times is in the headlamp guide.
• A power bank and the right cables, plus spare AAA cells if your lamp takes them.
• Your own food for the full segment plus two extra hours, and your own fluid.
• A warm layer, gloves and a hat for yourself. You will be moving slower than you are used to and you will get cold.
• Phone, fully charged, with an offline map of the course.
• Small first-aid basics, a whistle, an emergency blanket, and tape.
• A watch with enough battery life to cover the whole segment and show elapsed time and time of day.
• Paper: the cutoff card, and the runner's answers from the briefing.

If muling is permitted, add spares your runner is likely to need: a warm layer, gloves, a headlamp battery, and food they can face. If it is not permitted, carry those things only for yourself and know exactly where the line is.

The three clocks you run

Fuel. Your runner has lost the ability to track this. Do not ask whether they are eating; ask a specific question with a specific answer, every 20 to 30 minutes: what are you eating in the next ten minutes? Keep a running tally out loud. Do the same for fluid and for salt, using their plan rather than yours, and remember that intake needs to keep going in the dark when nothing tastes good; the options are in the aid-station food guide. If they are bloated, nauseated, with puffy fingers or a tight watch strap, stop pushing fluid and read the hyponatremia section of the electrolytes guide before doing anything else.

Time. You own the cutoff arithmetic so they do not have to carry it. Convert it into a single sentence: we have two hours ten to cover the next six miles, and we need to be moving in twenty minutes. Never share a calculation that sounds like panic, and never lie about the numbers. A watch that will survive the whole night, like the COROS Pace 3, matters here for the boring reason that a dead watch means you are doing time math on a phone in the cold.

Motion. Pick the line, set the hiking pace on climbs, call out when a section is runnable, and count out short efforts: run to the next switchback, hike to that rock. Run behind them unless they ask otherwise; it is usually the rule and it is always the courtesy, because it means your beam lights their ground rather than their shadow.

Night craft

Two lamps in a group light the trail better than one, so use yours to throw a wider pool rather than aiming it where theirs already points. Turn your head away before you talk to them, because a face full of 500 lumens at 3 a.m. is a genuinely miserable experience. Drop to a low mode when you stop, both to save battery and to keep some night vision.

The 2 a.m. to 4 a.m. window is the hardest part of any hundred, for both of you. It is colder than the numbers suggest, and sleepiness arrives as stumbling, slurred speech and wandering off the line before it ever arrives as a complaint. Fixes in order: caffeine in whatever form they practiced with, food, a layer, faster movement, and if none of that works, a deliberate ten-minute trail nap with an alarm. Sunrise fixes almost everything, and telling them how long until first light is one of the most useful things you will say all night.

Some things are not sleepiness. Confusion that does not clear after eating, shivering that stops in a cold runner, chest pain, wheezing, or a stumble that looks neurological rather than tired are all reasons to get to an aid station and hand over to medical. You are not the hero of this story, and no buckle is worth a bad outcome.

The low point, and the quitting conversation

Every hundred has at least one. Almost all quitting talk happens inside a low point, and it is a symptom rather than a decision.

Do not argue and do not give a speech. Diagnose instead: are they cold, hungry, nauseated, sleepy, chafed, blistered? Fix the fixable thing first, because a fed, warm runner usually stops talking about dropping within half an hour. Then shrink the horizon: not the finish, not the next ten miles, just the next aid station or the next twenty minutes.

Agree the rule in advance, at the pre-race briefing, and hold it on the night: nobody quits between aid stations, and nobody quits sitting in a chair before they have eaten something warm and been upright for ten minutes. Most drops that survive that test are real, and the ones that do not survive it were never real.

The exception is medical. If they are hurt in a way that running will worsen, showing signs of hypothermia or heat illness, or genuinely unwell, your job flips entirely: you become the person advocating to stop, and you say so plainly.

Handoffs and the crew

Arrive at your handoff station an hour before the earliest possible time your runner could get there, warm, fed and dressed. Runners arrive early far more often than crews expect.

Coming into a station with your runner, walk in with a report for the crew: what they have eaten and drunk in the last hour, what hurts, the state of their feet, and what they need out of this stop. Then let the crew be hands while you restock your own kit and eat something yourself, which pacers forget constantly. The division of labor is in the crew guide and the stop itself should follow the 90-second routine.

If another pacer takes over, brief them in thirty seconds: fuel status, mood, problems, what worked. Then go find food and sleep, and be at the finish line.

Things good pacers never do

• Set a pace the runner cannot hold, or drift ahead and make them chase.
• Say you look great to someone who visibly does not.
• Talk about their own races.
• Take aid they are not entitled to, or cut a switchback because the runner did.
• Make the low point about their own feelings.
• Leave after the finish. Get them warm, off their feet, and fed, and then take the credit you will never be offered.