How to Fuel for a 100 Mile Bike Ride in the Heat

How to Fuel for a 100 Mile Bike Ride in the Heat

So a few weeks ago, I rode the 100 mile Katy Flatlands ride here outside of Houston TX. My previous experience with these kinds of rides is that you can’t start off fast for the first 30-50 miles because you will hit a brick wall when temperatures are in the 90’s. I did that one year and I paid the price and wasn’t able to complete the century.

Everything was going fine until about mile 90, when my right leg started to cramp. I immediately took a salt tablet (100mg of sodium) and was able to continue on. As I crossed the finish line and pulled my feet out of one pedal, a shooting muscle cramp in my quad almost made me fall over. It was like no cramping pain I ever had. I took my bike to the car, and as I changed shoes, my quads and hamstrings cramped again as I bent down to tie my shoe laces. It was as if the cramping was getting worse now that I had finished the ride.

I was a little disturbed by this so when I got home, I told ChatGPT what had happened. I asked the platform to ask me all of the relevant questions it needed to figure out where I had gone wrong with my nutrition. Just for the record, my sweat test shows 20 ounces of fluids lost per hour. This is what Chatty gave me:

💥 WHY YOU CRAMPED

You were losing more sodium than you were replacing, especially in that heat.

            •Sweat Rate: 20+ oz/hour × 6 hours = ~120 oz lost

            •Estimated Sodium Loss: If you’re an average-to-salty sweater (~800–1,200 mg sodium per liter), you lost ~2,800–4,300 mg of sodium during the ride.

            •Sodium Replaced:

            •4 salt tabs × 100 mg = 400 mg total

            •Gatorade (20 oz/hr × 6 hrs) = ~840 mg sodium total (about 140 mg per 12 oz)

            •Gels: Most contain ~50 mg sodium each × 5 = ~250 mg

👉 Total Sodium Replaced = ~1,490 mg max

            •Deficit = 1,300–2,800 mg, which is likely what triggered the cramps.

So I asked Chat Gpt to come up with a nutrition plan for me for my next 100 mile ride coming up in 2 weeks (August 23^rd)

✅ YOUR NEW ELECTROLYTE & FLUID PLAN

🔁 Hourly Targets

Nutrient	Target (per hour)
Fluids	20–24 oz (you’re doing great here)
Sodium	500–700 mg/hour (increase!)
Carbs	40–60g/hour (you’re on track)

🔧 Updated Plan for 100-Mile Rides

1. Electrolytes

            •Use a higher sodium electrolyte mix than regular Gatorade (Ex: LMNT, Precision Hydration 1000 or 1500, Skratch High-Sodium, or Nuun Endurance). I recently bought the Nuun and it tastes great.

            •Alternate idea: Stay with Gatorade and add 1 salt tab (100–200 mg sodium) every 20–30 min.

            •Aim for ~600 mg sodium/hour minimum.

2. Fluids

            •You’re drinking the right amount (~20 oz/hr), but in hotter conditions, increase to 24 oz/hour if possible.

            •Consider using a bottle with concentrated electrolytes and another with plain water to avoid flavor fatigue. Flavor fatigue is real my friends- at one point in the ride all I wanted was plain water because I was so sick of Gatorade.

3. Fuel

            •Keep doing what you’re doing: 4–5 gels over 6 hours is great. (Actually, based on what I've read, 2 gels per hour is more like it.)

            •Just make sure each gel has at least some sodium.

🚨 EMERGENCY CRAMP PROTOCOL

If you start to feel cramps coming on:

            •Take 200–300 mg of sodium immediately (1–2 salt tabs or a quick electrolyte shot like HotShot or pickle juice). Yuk I hate pickle juice.

            •Stretch gently if possible while riding or slow cadence.

            •Increase fluid intake by 2–4 oz in the next 15 minutes.

📋 Simple Checklist for Next Race

✅ Drink 20–24 oz/hour

✅ Hit 500–700 mg sodium/hour

✅ 1 gel every 30–45 minutes (aim for 40–60g carbs/hour)

✅ Pre-load sodium the night before-750–1000 mg with dinner (Now this I really didn't think about!)

✅ Take a salt tab right before the ride starts

✅ Use high-sodium mix or add extra tabs to Gatorade

As an iron distance coach I've seen many athletes bonk even after spending a ton of money on a sports nutritionists to get the perfect nutrition plan for their race. The key is to practice practice practice your nutrition in the same conditions as you will be riding. Your longest rides and runs are a great opportunity to test out your nutrition each hour and figure out what works well and what doesn't.

Have you downloaded my Complete Guide to Triathlon Nutrition? I go over everything you need to know for each distance race for nutrition and hydration. You can get it by clicking HERE.

Have you thought about hiring an experienced coach for your next iron distance event? Let's talk! Fill out this short form and I'll get back with you shortly to set up our call!

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Mary Timoney

Ironman Certified Coach

USA Triathlon Coach

ACSM Trainer