Why Your Energy Crashes Halfway Through Every Ride

The Crash Is Not Random — It Has a Pattern

Mid-ride bonking has gotten complicated with all the conflicting nutrition advice flying around. Eat more fat. Go keto. Carbs are king. No wonder riders show up to their Sunday loop completely unprepared for what their body actually needs.

As someone who spent two full seasons bonking on the same stretch of road every single weekend, I learned everything there is to know about why energy crashes happen on the bike. Today, I will share it all with you.

Here’s the thing — a crash that happens at roughly the same point every ride isn’t bad luck. It’s a repeating cause. Three culprits account for nearly every mid-ride collapse I’ve seen or personally suffered through: glycogen stores running dry, blood sugar swings from poor carb timing, and dehydration that snuck up so gradually you never saw it coming. Let’s figure out which one is wrecking your rides.

Cause 1 — You Are Running Out of Stored Glycogen

Your muscles store somewhere around 90 minutes of fuel at moderate-to-hard effort. Maybe slightly more if you’re a larger rider or exceptionally fit. Maybe less if you’re grinding near threshold the whole time. When that tank hits empty, your legs send a very clear message.

But what is glycogen depletion, exactly? In essence, it’s your muscles running out of their primary stored fuel source. But it’s much more than that — it affects your brain, your coordination, your ability to hold a line. The legs go heavy in a specific way. Not just tired-heavy, but genuinely weighted down, like someone clipped ankle weights on while you were coasting. Your thinking goes foggy. The snap disappears from your pedals entirely. You start downshifting without consciously deciding to.

The mistake most riders make — and I made it for an embarrassingly long time — is waiting until hunger shows up before eating anything. Hunger is a terrible fueling signal on a bike. By the time it arrives, the glycogen tank is already drained. You’re already crashing, not approaching the crash.

Riding longer than 75 minutes without taking in any calories almost always points here. The fix isn’t glamorous. Start fueling at the 30- to 45-minute mark, before you feel hungry, before anything feels wrong. I spent an entire summer bonking around mile 20 on my 25-mile Sunday loop — roughly 75 minutes at my comfortable pace. I wasn’t eating a single thing until mile 18. I switched to taking a Maurten 100 gel at mile 8 and another at mile 16. The crash disappeared completely. Same route. Same fitness level. Totally different fueling plan.

Cause 2 — Your Carb Choices Are Spiking Then Dropping Your Blood Sugar

This one is sneaky. You’re technically eating enough carbs — the problem lives in the spacing.

You take a gel or a big swig of sports drink. Blood sugar spikes hard and fast. Your pancreas responds with insulin. Blood sugar drops. Twenty minutes later you’re in the basement wondering why you feel worse than before you ate. Then you eat again, spike again, crash again. That’s what makes erratic fueling so brutal — it punishes you for eating, which is the opposite of what’s supposed to happen.

Probably should have opened with this section, honestly. Blood sugar crashes feel almost identical to glycogen crashes on the bike, and most riders never realize their timing is the issue until they actually start writing down when they’re eating. I ate three Clif gels in ten minutes on a 4-hour group ride once because I was panicking about bonking. Then I didn’t eat again for nearly an hour. The spike-crash cycle that followed was genuinely miserable — foggy, shaky, irritable at mile 35.

The fix is spreading carbs across the ride instead of stacking them. Aim for 30 to 60 grams per hour depending on your size and effort. Pair fast carbs with something slower — a gel plus half a bar, a sports drink plus a handful of rice cakes, two gels with 30 minutes between them. What doesn’t work is dumping 90 grams into your stomach in one go and hoping for the best.

Cause 3 — You Are More Dehydrated Than You Think

Dehydration doesn’t always feel like desperate thirst. At just 2 percent body weight loss, you’re already seeing measurable performance drops and mental fog. Most riders don’t notice anything until they’re sitting at 3 or 4 percent — well past the point where the damage is done.

A dehydration crash has its own distinct signature, which is useful for diagnosis. You get a headache that wasn’t there 20 minutes earlier. Your legs feel heavy and hot and sluggish rather than empty. Perceived effort climbs even though your speed hasn’t dropped. You overheat easily. You might feel slightly dizzy accelerating out of a corner or standing up on a climb.

That’s what makes dehydration different from the other two causes — it feels like you’re cooking from the inside rather than running out of fuel. Your fitness is fine. Your carb timing might be perfect. But your blood volume and core temperature regulation are off, and your body is burning extra resources just to keep up.

I’m apparently a heavy sweater — around 900 milliliters per hour in warm weather — and carrying two 750ml Specialized Purist bottles works for me while a single bottle never, ever lasts. Don’t make my mistake. I learned this during a 90-minute tempo session in July. I was drinking whenever I happened to remember, which worked out to maybe 300 milliliters total per hour. Around minute 65, I crashed hard. Headache, overheating, a weird sluggish heaviness that felt completely different from any bonk I’d hit before. I started using a 15-minute phone alarm to remind myself to drink regardless of thirst. The crashes stopped.

On a moderate ride in normal weather, aim for 500 to 750 milliliters per hour depending on your size and conditions. Hot day, hard effort — bump that to 750 to 1000 milliliters. A standard bottle runs 600 to 750 milliliters, so the math is pretty straightforward from there.

How to Build a Pre-Ride and On-Ride Fueling Plan That Stops the Crash

So, without further ado, let’s dive in. While you won’t need a sports dietitian on retainer, you will need a handful of actual systems — not vibes, not guesses, not “I’ll eat when I feel like it.”

Pre-Ride Meal Timing

Eat a normal meal 2 to 3 hours before your ride. This is the glycogen-loading foundation everything else builds on. Oatmeal with a banana and peanut butter. Toast with eggs. Pasta with marinara. Nothing exotic or complicated. You want carbs with some protein and fat to slow digestion down — eat until comfortably full, not stuffed and sluggish.

First, you should eat something light 30 to 60 minutes before your ride — at least if you’re heading out early and a full meal isn’t realistic. A banana, a plain bagel, a Larabar. That small amount tops off liver glycogen, which stabilizes blood sugar in the opening miles when your body is still warming up.

On-Bike Fueling Timeline

Set a phone timer for 30 minutes after you roll out. Take your first calories right then. Before hunger. Before anything feels off. For rides under 90 minutes, that might be your only fueling stop. For longer rides, take calories every 30 to 45 minutes after that first alarm.

Carry enough to cover the full ride plus a 20-minute buffer. That’s roughly 120 grams of carbs for a two-hour ride — two gels and a bar, or three gels and a drink mix, or two Bobo’s bars and a bottle of Skratch. For three hours, double it. A frame bag holds all of this without issue. Jersey pockets work fine too if you’re running minimal kit.

Hydration Pacing

Fill your bottles before you leave. Set a separate alarm every 15 to 20 minutes — not thirst-based, schedule-based. A few genuine sips each time, not a symbolic mouthful. This spreads fluid intake across the ride and prevents the dehydration lag that catches riders off guard around the 60-minute mark.

A sports drink with carbs and electrolytes might be the best option for hot days, as endurance riding requires consistent sodium replacement. That is because sweat contains sodium, and plain water alone doesn’t replace what you’re losing — especially on efforts over 90 minutes in warm weather. Liquid calories also count toward your carb targets, which takes some pressure off solid food.

The Reality Check

The mid-ride crash is not a fitness problem. Your engine works. Your legs are fine. The logistics had gaps. Most riders solve this within two or three rides once they have an actual structured plan instead of winging it every time. That’s what makes this fixable — it’s repeating, which means it’s predictable, which means it responds to a repeating solution.

Start simple. Rides over 75 minutes? Eat something at the 30-minute mark. Drink on a timer, not on demand. Space carbs out across the ride instead of front-loading them. Write down what you ate, when you ate it, what you drank, and whether the crash showed up. One variable at a time. The pattern becomes obvious fast.