⏵ Course guide · San Antonio loop ultra
The Alamo City Ultra runs repeated loops of Eisenhower Park's rocky, rooty singletrack in San Antonio, 425 feet of gain per lap, with a 50K, 25K, 10K, and 5K all built from the same course. I will walk you through the loop structure and cutoffs first, then give you a pacing and fueling plan built for a hard 4:45 PM final-loop deadline, plus free tools to dial in your own numbers.
These facts come from the official Rise Racing Co. race page. Check the current year details, cutoffs, and aid stations before you commit. Race logistics change year to year.
Every distance is built from the same Eisenhower Park loop: the 50K runs it 6 times, the 25K 3 times, the 10K twice, and the 5K once. Rocks and roots dominate the natural trail sections, with some smoother greenway trail closer to the finish.
The official course description puts gain at 425 feet per loop. There is no single climb to plan for here: the challenge builds from technical footing on repeated laps rather than elevation. By your fourth or fifth loop on the 50K, the same roots and rocks you handled easily on lap one will demand real attention.
Aid sits at roughly 3.1 and 5 miles into each loop for the 50K and 25K, and at the finish line (mile 3.2) for the 10K. Because you pass aid multiple times per loop on the longer distances, you get frequent resupply chances rather than needing to carry a full race's worth of food and drink.
Alamo City Ultra also runs a ruck division: under 150 lbs body weight requires a minimum 20 lb ruck (without consumables), and over 150 lbs requires a minimum 30 lb ruck. If you are considering the ruck option, weigh in before race day to make sure you meet the minimum.
The real constraint on the Alamo City Ultra is not the overall 12 hour clock: it is the hard rule that you cannot start a new loop after 4:45 PM.
For the 50K, figure out how many of your 6 loops you need to complete before 4:45 PM to guarantee you can start your final lap. A race-time calculator projection gives you an average per-loop pace, but check that projection specifically against the 4:45 PM gate, since finishing "on time" overall means nothing if you miss the cutoff to start your last loop.
A grade-adjusted pace target for the rocky, rooty sections gives you an honest number for what you can hold across multiple laps, not just your fastest single loop. Runners who push hard on loop one often lose more time to fatigue-driven mistakes on the technical footing later than they gained early.
⏵ Free tools to pace this course
Late January in San Antonio usually runs cool to mild, but a 6:45 AM start on the 50K means you could still see a wide temperature swing across a full day on course.
Aim for roughly 60 to 90 grams of carbohydrate per hour on the 50K and 25K. Both aid stations are described as "full" and stocked with a wide range of Texas-style food, sweet and salty, plus hot food like quesadillas, soups, and ramen for anyone still out after dark. Use that variety to keep eating real food across multiple loops rather than relying only on gels.
Sodium in the 300 to 700 mg per liter range covers most runners in mild San Antonio winter conditions. Since this is a cupless race, bring your own bottle or reusable cup for every aid stop, since none will be provided.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a mild January San Antonio day with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a race-day plan built around YOUR fitness, this exact 425 ft loop profile, and your projected per-loop splits. Summit Line reads your real training, builds a plan for repeated technical loops, and rehearses your fueling so race day is something you execute, not guess at.
The official course description calls it "a fun and challenging" loop with 425 feet of elevation gain per lap, run on natural trail through lots of rocks and roots with some greenway sections near the finish. It is not a mountain course, but repeating the same technical loop up to six times for the 50K rewards familiarity with the footing over raw fitness alone.
The official race page states 425 feet of elevation gain per loop. The 50K runs 6 loops, the 25K runs 3, the 10K runs 2, and the 5K runs 1, but the site does not publish a total gain figure per distance, so treat 425 ft per loop as your building block rather than a confirmed total.
This is a cupless race, so bring your own reusable cup, bottle, or hydration pack. The two full aid stations are stocked with Gatorade, water, and electrolyte mix, plus sodas, cookies, candy, peanut butter, Nutella, Pringles, trail mix, chips, PB&Js, bean burrito rolls, and fresh fruit, with hot food like quesadillas, soups, and ramen for the PM hours. Aim for roughly 60 to 90 grams of carbohydrate per hour on the 50K and 25K, and sodium in the 300 to 700 mg per liter range. Build your own numbers with the free ultra fueling calculator before race day.
The overall event cutoff is 12 hours, but the harder constraint is that you cannot start a new loop after 4:45 PM, no exceptions. On a 6-loop 50K, that means your pacing has to keep you on track to begin your final loop well before the 4:45 PM gate, not just finish inside 12 hours on paper.
Distance changes are allowed online until the Wednesday of race week through UltraSignup, with a small fee to move up and no refund of the difference to move down. Once your race begins, though, you must finish the distance you started: there is no dropping down mid-race, and doing so counts as a DNF for your original distance regardless of the reason.
The loop format (6 laps of the same course) means frequent access to the main aid station and easy crew logistics, which is friendlier for a first ultra than a remote point-to-point race. With a 400 runner cap and only 425 feet of gain per loop, this is an approachable Texas ultra for a first attempt, as long as you respect the hard 4:45 PM final-loop cutoff.
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<a href="https://runsummitline.com/guides/alamo-city-ultra">The Alamo City Ultra course guide</a><iframe src="https://runsummitline.com/embed/race/alamo-city-ultra" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Alamo City Ultra course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.
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