Staring at a 200km or 300km ride on paper can feel overwhelming. But what if you didn't think about it as one massive ride? Chunking is a strategy used by many ultra-endurance cyclists to break a long ride into smaller, more manageable blocks. Instead of worrying about the whole day, you only need to think about the next chunk.
It doesn't work for everyone - some riders prefer a less structured, more intuitive approach, and that's fine. But for those who like a framework to plan around, chunking can turn an intimidating distance into a series of achievable sessions.
What Is Chunking?
Chunking is a technique borrowed from psychology - the idea that we handle complex tasks better when broken into smaller pieces. While widely used in coaching and supported by general cognitive psychology, it's not a scientifically proven "optimal" approach to cycling. It's a practical framework that many riders find helpful.
For cycling, it typically means dividing a long ride into blocks, each with its own plan for nutrition, effort, and logistics. There are several ways to chunk a ride:
Time-Based Chunking
The most common approach. Divide the ride into blocks of 3-5 hours. A flat, fast 120km in 4 hours is one chunk. A mountainous, slow 80km in the same 4 hours is also one chunk. You're thinking in terms of time, not distance.
Best for: Riders with power meters or HR monitors who can pace by time. Events with predictable conditions.
Distance-Based Chunking
Break the ride into segments between landmarks - towns, feed stations, mountain passes. "I just need to get to Bakewell, then I'll think about Buxton." Each segment has a clear destination.
Best for: Events with well-spaced checkpoints. Riders who find towns and landmarks more motivating than abstract time blocks.
Task-Based Chunking
Focus on specific tasks within short windows rather than distance or time: "For the next 30 minutes, I'm going to focus on cadence." Then: "For the next 30 minutes, I'm going to eat and drink properly." Then: "For the next 30 minutes, I'm going to check posture and relax my shoulders."
Best for: The really hard hours. When you're too tired for long-term planning, narrowing focus to a single task keeps you moving. Also useful for managing fatigue-related pacing errors.
Most riders use a combination - time-based chunks for overall structure, with task-based micro-chunks when things get tough late in the ride.
Connecting Chunking to Pacing
Chunking isn't just psychological - it's a practical tool for effort management. Each chunk should have its own intensity target, not just a nutrition plan.
Early chunks (hours 0-4): Ride at the lower end of your sustainable range. If you have a power meter, this might be 60-70% of FTP. It will feel too easy. That's the point - you're banking energy for later. (See our pacing guide for ultra rides for more on intensity ranges.)
Middle chunks (hours 4-8): Maintain a steady effort. Heart rate will drift upward at the same power - that's normal. Your focus shifts from "hold back" to "stay consistent."
Late chunks (hours 8+): Power will decline. Accept it. The chunk structure helps here - instead of thinking "I've still got 80km to go and I'm fading," you think "I just need to get through this chunk." Reduce intensity targets for late chunks when planning.
This matters because riders who chunk without pacing tend to ride each chunk at the same intensity - which means the early chunks are too hard. Match your chunk plan to a declining intensity curve.
Planning Your Chunks
Within each chunk, plan three elements:
Riding time: How many hours of actual pedalling? Be realistic about pace, terrain, and fitness level.
Rest stops: Plan 3-15 minutes depending on needs. A quick snack stop might be 3 minutes; a meal break might be 20-30 minutes. Include these in your total chunk time.
Nutrition targets: Aim for 60-90g of carbohydrates per hour during the ride. For a 4.5-hour chunk, that's roughly 270-400g of carbs total. Mix sports nutrition (gels, chews, bars) with real food (sandwiches, rice cakes, bananas) for variety and satiety.
Hydration: Plan for 500-750ml of fluid per hour, adjusted for heat and humidity.
Tip: A simple formula: for each chunk, calculate your calories (roughly 200-300 per hour for endurance pace), your fluid needs, and any gear changes needed. Write it all down - don't rely on memory when you're tired.
The Chunk Bag
The practical magic of chunking is preparation. Before the ride, you prepare a bag (or container) for each chunk containing everything you need:
- Food: Energy bars, gels, chews, sandwiches, rice cakes, fruit - whatever works for your stomach
- Drink: Pre-mixed bottles with electrolytes, or powder sachets ready to mix
- Spare kit: Arm warmers, gilet, rain jacket - gear for changing weather or temperature shifts
- Spares: Inner tube, CO2 cartridge, chain lubricant
- Personal items: Sun cream, lip balm, medication, blister treatment
When you finish one chunk and pull into your rest stop, you grab the next bag and you're ready to go. No faffing, no forgetting things. Each bag is self-contained, and the mental shift from "I just finished the first 4 hours, only 8 more to go..." to "I finished chunk 1, time to crack on with chunk 2" is surprisingly powerful.
Support Scenarios
How you set up your chunks depends on the type of support available.
Loop Routes
If your route loops back to a base (home, car park, hotel), you can leave chunk bags there. Ride out, come back, swap bags, head out again. This is common for audax-style training rides and events with a headquarters.
Escort Vehicle
With a support car following or leapfrogging ahead, the driver holds your chunk bags and hands them over at pre-arranged points. The driver can also prepare hot food, refill bottles with cold water, and hold spare clothing. This is common in events like RAAM (Race Across America) and LEL (London-Edinburgh-London) where supported riders have crew.
Self-Supported
For bikepacking or unsupported audax rides, you carry your chunk supplies on the bike. The chunk bag concept still works - organise supplies in separate ziplock bags or stuff sacks, one per chunk. When one's finished, move to the next.
Drop Bags
Some events let you send bags ahead to checkpoints. Pack each drop bag as a chunk bag - everything you need for the next section. Label clearly with your name and the checkpoint number. Include a "Plan B" food option in each bag in case your stomach rebels against your primary choices.
When Chunking Goes Wrong
Chunking is helpful for many riders, but it has failure modes worth knowing about:
Chunks too small: Breaking a ride into 30-minute or 1-hour blocks can become obsessive and stressful. You spend more time thinking about transitions than riding. If you're clock-watching every 45 minutes, your chunks are too granular. Exception: task-based micro-chunks (focus on cadence, focus on eating) work well at small timescales precisely because they're about attention, not logistics.
Chunks too large: If a chunk is 6-8 hours, it loses the psychological benefit. The point is to make each block feel achievable. For most riders, 3-5 hours is the sweet spot - long enough to make meaningful progress, short enough to feel manageable.
Ignoring body signals: The chunk plan should serve you, not the other way around. If your plan says "ride for 4 more hours before stopping" but your body says "eat now" - eat now. Rigid adherence to a plan when conditions change (weather, mechanicals, stomach problems, unexpected fatigue) is worse than no plan at all. Chunking is a framework, not a contract.
Same intensity every chunk: Planning four identical chunks ignores the reality that your body deteriorates over time. Late chunks should have lower intensity targets, more rest, and different food choices (simpler, easier to digest). See the worked example below.
A Worked Example
Here's how chunking might look for a 300km audax in 15 hours:
Chunk 1 (0-75km, ~4.5 hours): Target 60-70% FTP. 3 bottles, 4 gels, 2 flapjacks, 1 banana, arm warmers (early morning start - you'll need them). This chunk should feel easy. If it doesn't, you're going too hard.
Chunk 2 (75-150km, ~4.5 hours): Target 55-65% FTP. 3 bottles, 4 gels, 2 sandwiches, electrolyte tabs. Drop the arm warmers - it's warmed up now. RPE should be 4-5. You may start passing riders who went out harder.
Chunk 3 (150-225km, ~4 hours): Target 50-60% FTP. 3 bottles, 4 gels, 1 sandwich, energy chews. Add a gilet (afternoon cooling kicks in around the 200km mark). Power may drop 10% - accept it and keep eating.
Chunk 4 (225-300km, ~3 hours): Target whatever keeps you moving. 2 bottles, 3 gels, caffeine tabs (you'll need the boost), front light plus spare battery (if finishing in the dark). This is survival chunking - focus narrows to "get to the next town."
Total across all chunks: 11 bottles, 15 gels, 3 sandwiches, 2 flapjacks, 1 banana, electrolyte tabs, caffeine tabs, arm warmers, gilet, light, batteries.
Notice how each chunk is different? Early on you're adding layers; later you're adding caffeine and lights. Food shifts from sandwiches (when you have appetite and time) to gels (when you just want to keep moving). And crucially, intensity targets decline - chunk 1 is not the same effort as chunk 4.
How PitStopper Helps
Chunking becomes more powerful when combined with route planning:
- Identify refill points: Use PitStopper to find water taps, cafes, and shops within each chunk of your route. This tells you where you can top up without getting caught short.
- Clock time features: PitStopper's clock time feature shows when you'll arrive at each point - useful for knowing if shops will be open or if there's shade for a break.
- Export waypoints: Export your route with chunk boundaries marked as waypoints to your GPS device. You'll get alerts when each chunk is coming to an end, keeping you mentally on track.
- Split your route: Use PitStopper's split route feature to match your chunks, giving you distance and elevation stats for each segment. If chunk 3 has 1,000m of climbing, you might need more time or fuel.
Tip: Before your event, load your GPX route into PitStopper and add custom waypoints at each chunk boundary. Include the anticipated arrival time in the waypoint name (e.g., "Chunk 2 - 2:30pm"). When you export to your GPS, you'll have a clear timeline for the entire event.
Tips for Getting Started
- Start with your total ride time and divide into roughly equal chunks. A 12-hour ride becomes three 4-hour chunks. A 15-hour ride becomes three 5-hour chunks.
- Plan nutrition per chunk first. This is the most important element. Get carbs and hydration right, and everything else falls into place.
- Set declining intensity targets. Each chunk should be slightly easier than the last. If every chunk has the same power target, you're planning to blow up.
- Pack each chunk bag the night before. Label them clearly (Chunk 1, Chunk 2, etc.) so there's no confusion during the ride when you're tired.
- Practice on training rides. Test your chunk duration and nutrition plan before race day. A 300km audax is not the time to discover your stomach can't handle those particular gels.
- Be flexible. If you're ahead or behind schedule, adjust the remaining chunks. Chunking is a framework, not a prison.
- Include a bail-out plan. Know where you can cut the route short if needed - a train station, a taxi rank, a place to stay overnight. Ultra-distance cycling can take turns; have an exit strategy.
Conclusion
Chunking won't make the kilometres disappear, but for many riders it turns an intimidating distance into a series of achievable sessions. It's not the only way to approach ultra-distance cycling - some riders thrive on intuition, others on strict schedules - but it's a solid framework to start from, especially if you're new to long events.
The key is to use it as a tool, not a rulebook. Plan your chunks, plan your nutrition, set declining intensity targets - and then be willing to throw the plan out if your body tells you something different. The best ultra riders are the ones who can plan meticulously and adapt fluidly. Chunking gives you the plan; experience teaches you when to deviate.
