There is a stat I come back to every time I sit down with a new athlete in the Roadman community: the gap between what most amateur cyclists eat on the bike and what the cycling nutrition research says they should eat. It is not a small gap. It is not a rounding error. It is, in most cases, a factor of two.
The average age-group rider consumes somewhere around 30-40g of carbohydrate per hour during a hard ride. The current evidence — from Jeukendrup, Podlogar, Impey, and every World Tour nutritionist who has been on the podcast — points to 60-90g per hour for sustained efforts, with the upper end increasingly achievable through gut training. Some elite riders are now hitting 120g per hour in racing. The amateur is eating half what they should, then wondering why they fade in the last third of every ride, bonk on sportives, and feel wrecked for two days afterwards.
This is not a knowledge problem for everyone. Some riders simply do not know the targets. But most have heard the numbers. They have read the articles. They just have not built the habits, trained the gut, or created a plan they can execute under pressure. Knowing the science and doing the science on the bike at kilometre 130 are different skills entirely.
The Fuelling Self-Assessment was built to close that gap — not by telling you what to eat, but by scoring where your current practices fall short and showing you which fix matters most. This guide walks through the science behind each scoring category, explains the real costs of getting it wrong, and gives you the framework to build a fuelling strategy that works on race day, on training days, and on the days in between.
The Real Cost of Under-Fuelling
Under-fuelling on the bike is not just uncomfortable. It is performance-destroying, health-damaging, and self-perpetuating. Most riders think of it as a bonking problem — run out of glycogen, hit the wall, crawl home. That is the visible symptom. The invisible damage is worse and accumulates over months.
The Performance Cost
When muscle glycogen drops below a critical threshold, the body does not simply slow down — it protects itself by reducing the intensity it will permit. Power output falls. RPE climbs. The same wattage that felt sustainable an hour ago now feels impossible. This is not fatigue in the traditional sense; it is a central governor response, the brain dialling down motor unit recruitment because the fuel supply is compromised.
The data from Sam Impey's work with World Tour teams shows that riders who sustain 80-90g of carbohydrate per hour during stage racing maintain higher power outputs in the final hour of racing compared to riders at lower intakes — even when total calorie intake across the day is similar. The timing and the rate of delivery matter independently of the total.
For amateur cyclists, the performance cost is worse because the baseline is lower. A World Tour rider under-fuelling from 90g to 60g per hour is still above most amateurs' maximum. An amateur dropping from 30g to 15g per hour — which happens every time they skip a feed or cannot stomach a gel — crosses the threshold where meaningful performance degradation begins.
The Recovery Cost
Under-fuelled rides are expensive rides. Not in the moment, but in the hours and days that follow. Glycogen replenishment is a rate-limited process, and starting that process from a deeper deficit takes longer. A rider who finishes with severely depleted glycogen stores needs 24-36 hours of adequate carbohydrate intake to fully restore them. A rider who maintained intake during the ride — even imperfectly — starts recovery with a partial tank and needs significantly less time.
The downstream effect is cumulative. Under-fuel on Tuesday, and Wednesday's session is compromised. Under-fuel on Wednesday too, and Thursday is a write-off. Over weeks, this pattern erodes the consistency that matters more than any single session. You are not just losing the quality of the ride you under-fuelled. You are degrading the quality of every ride that follows it until the debt is repaid.
The Immune Cost
Hard exercise suppresses immune function for a window of 3-72 hours post-ride — the so-called "open window" that makes endurance athletes disproportionately susceptible to upper respiratory infections. Under-fuelling extends that window and deepens the suppression. Nieman's research has shown that carbohydrate intake during exercise measurably reduces the post-exercise cortisol spike, the drop in circulating lymphocytes, and the inflammatory markers associated with immune suppression.
The practical implication: riders who under-fuel chronically get sick more often, lose more training days to illness, and build fitness more slowly — not because of any single ride, but because of the accumulated immune cost of dozens of under-fuelled sessions across a season.
The Hormonal Cost: Energy Availability
This is where under-fuelling crosses from performance problem to health problem. Energy availability (EA) — the energy remaining for normal body functions after subtracting exercise expenditure — is the metric that connects daily nutrition to hormonal health. The threshold is 30 kcal/kg of fat-free mass per day. Below it, the body begins downregulating systems it considers non-essential: reproductive hormones, thyroid function, bone metabolism, immune capacity.
This condition, now termed Relative Energy Deficiency in Sport (RED-S), is not exclusive to underweight athletes or those with eating disorders. It affects amateur cyclists who are training hard, eating what they think is enough, and running a chronic deficit because they underestimate exercise expenditure, overestimate dietary intake, or both. The Energy Availability Calculator puts a number on this. Use it.
"The athletes who struggle most with fuelling are not the ones who eat too little — they are the ones who eat enough total calories but at the wrong times. They starve the performance and flood the recovery."
— Dr Sam Impey, World Tour nutritionist (Roadman Cycling Podcast)
The Four Pillars of Smart Fuelling
The Fuelling Self-Assessment scores four categories because fuelling is not one thing. You can get the total grams right but take it all in at the wrong time. You can time it well but use the wrong carbohydrate sources. You can have the perfect plan on paper and fall apart when your gut refuses to cooperate at hour three. Each pillar addresses a distinct failure mode, and most riders are weak in at least two.
Pillar 1: Timing
When you eat matters almost as much as what you eat. The most common timing mistakes I see in the community fall into a predictable pattern:
Pre-ride: Eating too close to the start (causing GI distress) or too far out (arriving glycogen-depleted). The window is 2-3 hours before hard sessions, with a small top-up of 20-30g of easily absorbed carbohydrate in the final 15-20 minutes.
During the ride: Waiting too long to start eating. Most riders feel fine for the first 60-90 minutes and delay their first intake until they start to feel the effort — by which point glycogen depletion is already underway. Start eating within the first 30 minutes of any ride over 90 minutes. The early feeds are the easiest to absorb and the most valuable for delaying the onset of fatigue.
Post-ride: The recovery window is real but widely misunderstood. The 30-minute post-ride window is not magical, but glycogen synthase activity is elevated immediately after exercise, and consuming 1-1.2g/kg of carbohydrate with 0.3-0.4g/kg of protein in the first 30-60 minutes accelerates replenishment measurably compared to waiting two hours. For riders training again within 24 hours, this timing matters. For those with 48 hours between sessions, total daily intake matters more than the exact minute of the post-ride meal.
Pillar 2: Quantity
This is where the biggest gap lives. The targets, by ride type:
- Easy rides under 60 minutes: Water. Possibly nothing else.
- Moderate rides 60-90 minutes: 30-40g/hour if the session includes intensity. Water and a gel or a banana will cover it.
- Hard rides over 90 minutes: 60-90g/hour. This is the range where most amateurs fall short by half.
- Racing and very hard sessions: 80-120g/hour. The upper end requires trained gut and glucose-fructose combinations.
The numbers are not arbitrary. They track the maximum oxidation rates of exogenous carbohydrate. Glucose alone maxes out at roughly 60g/hour because the SGLT1 intestinal transporter saturates. Adding fructose, which uses a separate transporter (GLUT5), opens a second absorption pathway and pushes the ceiling above 90g/hour. This is why every World Tour drink mix and gel now uses a glucose-fructose or maltodextrin-fructose blend — it is not marketing, it is physiology.
Use the In-Ride Fuelling Calculator to set your target. Then use the Calories Burned Calculator to understand the total energy cost of your sessions and ensure your daily intake supports it.
Pillar 3: Composition
Not all carbohydrates are equal during exercise. The composition of what you eat determines how fast it clears the gut, how rapidly it enters the bloodstream, and how much GI distress it causes.
Glucose-fructose combinations are the gold standard for high-rate fuelling. The optimal ratio sits between 2:1 and 1:0.8 (glucose to fructose). Maltodextrin — a polymer of glucose — is often used in place of pure glucose because it has lower osmolality, meaning it moves through the stomach faster and causes fewer issues.
Gels deliver a precise, fast-absorbing dose. Their weakness is monotony and the cloying sweetness that becomes intolerable after four hours.
Drink mix is the most efficient delivery method because it combines hydration and fuelling. The risk is getting the concentration wrong — too concentrated, and it sits in the stomach; too dilute, and you cannot hit your gram target without overloading on fluid. Use the Hydration Calculator to get the fluid side right.
Real food — rice cakes, dates, jam sandwiches, fig bars — adds palatability and psychological variety on rides over three hours. It absorbs more slowly than gels and drink mix, which is fine when you are eating consistently and not trying to catch up from a deficit. The homemade race fuel recipes on the site cover this in detail.
Fibre and fat have no place in your on-bike nutrition. Both slow gastric emptying. Both increase the risk of GI distress. Keep them for meals either side of the ride.
Pillar 4: Practice (Gut Training)
This is the pillar most riders skip entirely, and it is the one that makes the other three possible.
Gut training is not a metaphor. It is a measurable physiological adaptation. Jeukendrup's research — and the subsequent work by Podlogar, King, and others — has demonstrated that the intestinal transporters responsible for carbohydrate absorption (SGLT1 for glucose, GLUT5 for fructose) upregulate in response to regular carbohydrate feeding during exercise. The capacity of the gut to absorb and tolerate high carbohydrate loads is trainable, in the same way that VO2max and lactate threshold are trainable.
The protocol is simple:
- Establish your current tolerance. Whatever you are eating per hour right now without GI distress is your baseline.
- Increase by 10g per hour per week. If you are at 30g/hour, aim for 40g next week, 50g the week after.
- Practise on training rides, not races. Gut training adaptations need 2-4 weeks of consistent exposure. Build them into your normal training well before any target event.
- Use glucose-fructose combinations from the start. The dual-transporter approach is more tolerable at high rates than glucose alone.
- Practise with the products you will use on race day. GI tolerance is partly product-specific, not just quantity-specific.
The riders who skip gut training are the ones who try 90g/hour on race morning, spend 40 minutes in a portaloo, and conclude that high-carb fuelling "does not work for them." It works for almost everyone. But it requires practice, exactly like threshold intervals or long endurance rides.
Common Fuelling Mistakes by Rider Type
Over the past five years of coaching and running the community, I have seen the same fuelling mistakes cluster into recognisable profiles. Most riders are a blend of two or three. The value of naming them is recognition — you fix what you can see.
The Dieting Rider
This rider is trying to lose weight and fuel hard rides at the same time, usually by restricting carbohydrate across the board. The result is chronically low glycogen stores, poor session quality, elevated cortisol, and — paradoxically — slower body composition progress because the hormonal environment they create is one that fights fat loss and promotes muscle breakdown.
The fix is fuel for the work required. Eat around your hard sessions. Create the deficit on easy days and rest days, where reduced glycogen stores have minimal performance cost. The concept is covered in depth in the FFTWR guide and the body composition calculator can help set the numbers.
The "I'll Eat When I Stop" Rider
This rider carries food but does not eat it until a cafe stop or the halfway point of a sportive. By the time they eat, they are already in a glycogen hole that the food they consume cannot dig them out of quickly enough. Gastric emptying slows when exercise intensity is high, so the large feed they take at the stop sits in their stomach and causes more distress than the steady drip of smaller feeds would have.
The fix is an alarm. Set a timer on your bike computer for every 20 minutes. When it goes off, eat something. Not a big meal. A gel. A few sweets. A mouthful of drink mix. Frequency and consistency beat volume.
The Gel-Only Rider
This rider has the discipline to eat regularly but relies exclusively on gels. By hour three, the sweetness is nauseating and they stop eating — reverting to the "I'll eat when I stop" pattern. Gel fatigue is real, and it is entirely avoidable with a bit of variety.
The fix is a mixed approach. Two-thirds of your carbohydrate from drink mix and gels, one-third from real food (rice cakes, dates, savoury options). The variety in flavour and texture keeps you eating when pure sweetness would shut you down.
The Real-Food Purist
This rider distrusts processed sports nutrition and fuels exclusively with "real" food — homemade bars, fruit, sandwiches. The food is fine. The problem is rate of absorption. Solid food absorbs more slowly than gels and drink mix, and the fibre content of some real foods slows gastric emptying further. At moderate intake rates (40-50g/hour), this works. At 80g+ per hour, the rider hits a ceiling they cannot break through with solid food alone.
The fix is not abandoning real food — it is supplementing it. Use drink mix as the foundation (30-40g/hour of your total) and top up with real food. This gives you the absorption speed when you need it and the palatability benefits of solid food.
The Under-Hydrated Fueller
This rider gets the food right but the fluid wrong. Dehydration as mild as 2% of body weight impairs gastric emptying, which means the carbohydrate they are consuming sits in the stomach instead of reaching the intestine where it can be absorbed. The result is GI distress, reduced absorption, and the false conclusion that they "cannot tolerate" high carbohydrate intake.
The fix is separating the two calculations. Use the Hydration Calculator to set your fluid target independently of your carbohydrate target, then build a plan that delivers both. In hot conditions, err on the side of slightly more fluid — the GI benefits of adequate hydration compound with every gram of carbohydrate you consume.
Building a Race Nutrition Plan From Scratch
A race nutrition plan is not a luxury reserved for elite athletes. It is a checklist that removes decision-making from a moment when decision-making is compromised by fatigue, adrenaline, and pain. Here is how to build one.
Step 1: Set Your Carbohydrate Target
Use the Fuelling Calculator with your estimated race duration and intensity. For a 3-hour sportive at threshold-adjacent intensity, you are looking at 60-80g/hour. For a 5-hour event with variable intensity, 70-90g/hour during hard phases and 40-50g/hour during easy phases.
Step 2: Choose Your Sources
Split the total across three delivery formats:
- Drink mix: 30-40g/hour (the constant baseline)
- Gels: 20-30g as bolus feeds every 30-40 minutes
- Solid food: 10-20g/hour from rice cakes, bars, or dates (first half of the race only — shift to liquid and gels as intensity rises)
Step 3: Map It to the Course
Print or write down a feed schedule tied to time, not distance. Every 20 minutes, something goes in. Mark the feeds on your top tube or programme them as intervals on your bike computer. Account for feed zones if the race provides them, and carry enough to be self-sufficient if they run out of what you need.
Step 4: Set Your Hydration Alongside It
Use the Hydration Calculator to estimate fluid needs based on expected temperature, humidity, and your sweat rate. Two bottles per hour in heat, one in cool conditions, adjusted by feel. Take electrolytes with every bottle — sodium is the main loss in sweat, and replacing it maintains plasma volume and gut absorption.
Step 5: Rehearse the Whole Plan
Race-day fuelling that has not been practised is a guess. Run the full plan — products, quantities, timing — on at least three training rides of similar duration and intensity before the event. This is where gut training and race rehearsal overlap: you are training your gut and testing your logistics at the same time.
Daily Nutrition: The Fuel You Burn Off the Bike
In-ride fuelling gets the attention, but daily nutrition is the platform everything else sits on. A rider who nails 80g/hour on the bike but chronically under-eats total calories, protein, or micronutrients is building on a cracked foundation.
Energy Availability: The Non-Negotiable
Energy availability (EA) is the single most important metric in daily nutrition for any endurance athlete. The formula:
EA = (Energy Intake − Exercise Energy Expenditure) ÷ Fat-Free Mass
The minimum threshold for maintaining normal physiological function is 30 kcal/kg FFM/day. Below this threshold — consistently, over weeks — the body begins shutting down non-essential systems. Menstrual function in women. Testosterone production in men. Bone metabolism. Immune capacity. Thyroid output.
This is not theoretical. It is documented extensively in the RED-S literature and covered in the energy availability guide on this site. For a 75kg male rider with 15% body fat (63.75kg FFM), the minimum daily energy intake after accounting for exercise expenditure is approximately 1,912 kcal — and that is the floor, not a target. Optimal EA for performance and health sits at 40-45 kcal/kg FFM/day.
Use the Energy Availability Calculator to check your numbers. If you are training hard and sitting below 30 kcal/kg FFM/day, nothing else in this guide will work properly until that deficit is corrected.
Protein: Timing and Distribution
Endurance cyclists need 1.6-2.0g of protein per kilogram of bodyweight per day. The upper end applies when training load is high, when you are in a caloric deficit (to protect muscle mass), or when you are over 40 (to counteract anabolic resistance).
But total daily protein is only half the equation. Distribution across meals matters. The muscle protein synthesis (MPS) response has a refractory period — dumping 80g of protein at dinner and eating 10g at breakfast is less effective than spreading 30-40g across four meals. The post-ride feed should include 0.3-0.4g/kg of protein alongside carbohydrate. A pre-sleep dose of 30-40g of casein-rich protein (cottage cheese, Greek yoghurt, or a casein shake) extends the overnight MPS window — a tactic covered in the bedtime protein protocol.
Periodising Daily Nutrition
The concept of nutrition periodisation — adjusting daily carbohydrate intake to match the demands of each training day — is borrowed from the World Tour and adapted for amateurs. The principle:
- Hard training days and race days: High carbohydrate (6-10g/kg/day). Fuel the work. This is not the day to create a deficit.
- Moderate training days: Moderate carbohydrate (4-6g/kg/day). Enough to support the session and recovery.
- Easy days and rest days: Lower carbohydrate (3-4g/kg/day). If you want a deficit, this is where to put it.
This approach — fuel for the work required — protects training quality on the days that drive adaptation while creating space for body composition goals on the days that do not carry a meaningful training stimulus. The nutrition periodisation guide covers the framework in full.
Caffeine: The Legal Ergogenic That Most Riders Waste
Caffeine at 3-6mg/kg bodyweight, consumed 30-60 minutes before exercise, improves endurance performance by 2-4% in controlled trials. For a 75kg rider, that is 225-450mg — roughly two strong coffees or three standard caffeine gels. The evidence is about as strong as it gets in sports nutrition.
The problem is not that riders do not use caffeine. It is that they use it indiscriminately. Three coffees a day, every day, year-round. By the time race day arrives, their tolerance is so high that the ergogenic dose barely registers.
Caffeine Periodisation
The fix is periodisation. Reduce daily caffeine intake to under 50mg per day (roughly one weak cup of tea) for 7-10 days before a target event. This is enough time for adenosine receptor sensitivity to partially reset. Then take the full dose — 3-6mg/kg — on race morning. The subjective and objective effects are markedly stronger in a rider who has pulled back than in a rider who has been drinking four espressos a day for the past six months.
Practical notes:
- The withdrawal period is uncomfortable. Headaches, fatigue, irritability for 2-4 days. Plan it during a recovery week.
- You do not need to go to zero. Cutting from 400mg/day to 50mg/day is enough to restore most of the sensitivity.
- Caffeine gels work faster than coffee because the caffeine is absorbed in the mouth and upper GI tract rather than having to clear the stomach.
- Late-race caffeine (a gel with 75-100mg caffeine at the 2/3 mark) can provide a second lift if the event is over 3 hours.
The Supplements That Actually Have Evidence
The supplement industry sells thousands of products to endurance athletes. The number worth buying is small, and all of them come with the same caveat: they work only if there is a deficiency or a specific physiological rationale, and most require blood work to know whether you need them.
Vitamin D
Vitamin D is involved in muscle function, immune regulation, bone metabolism, and inflammatory response. Deficiency is common in athletes who train indoors, live at higher latitudes, or have darker skin. Target blood levels above 75 nmol/L (30 ng/mL). Below that, supplementation with 2,000-4,000 IU/day through winter months is standard practice. Get tested annually — the dose should be guided by your actual levels, not a guess.
Iron
Iron deficiency is the most common nutritional deficiency in endurance athletes, especially women and athletes who restrict red meat. Symptoms — fatigue, elevated heart rate at low intensity, poor recovery — overlap with overtraining, which is why so many cases go undiagnosed. Test ferritin and serum iron with a full blood count. Do not supplement without confirmed deficiency — excess iron is toxic and the body has no mechanism to excrete it.
Omega-3 Fatty Acids
EPA and DHA (the omega-3 fats found in oily fish and algae supplements) have anti-inflammatory properties that support recovery, reduce exercise-induced muscle damage markers, and may improve heart rate variability. The evidence is not as strong as for vitamin D, but it is reasonable. Aim for 2-3g combined EPA/DHA per day from diet or supplementation, particularly if your diet is low in oily fish.
Everything Else
Creatine has emerging evidence for masters athletes (covered in the 30-day experiment). Beta-alanine has modest support for short, high-intensity efforts. Beetroot juice (nitrates) has some evidence for time-trial performance. Beyond those, the supplement aisle is largely marketing.
The money most cyclists spend on supplements would be better spent on blood work (to know what they actually need) and food (to close the gaps). One blood test per year — ferritin, vitamin D, full blood count, thyroid panel — costs less than three months of random supplement purchases and tells you exactly where to invest.
Using the Fuelling Self-Assessment
The Fuelling Self-Assessment scores twelve questions across the four pillars — timing, quantity, composition, and practice. Each question is scored 0-3, giving a total between 0 and 36. The scoring bands:
- 0-12 — Fuelling Deficit (Red): Your fuelling practices are significantly below the evidence-based targets. The performance and health costs are almost certainly active. Start with the pillar where you scored lowest and make one change per week.
- 13-22 — Fuelling Gaps (Amber): You have the basics in place but meaningful gaps remain. Most riders land here, and the fixes at this level deliver the biggest return — you are close enough to good practice that small changes produce visible results.
- 23-30 — Good Fuelling (Green): Your fuelling is solid. The gains from here are marginal and come from refinement — race rehearsal, product optimisation, and periodisation.
- 31-36 — Dialled Fuelling (Blue): You are doing this well. The only question is whether you are executing this consistently under race pressure and in varied conditions.
Take the assessment before and after building your fuelling plan. The number tells you where you were, but the distribution across pillars tells you where to focus. A rider who scores 24 overall but has a 2 in gut training needs a different intervention than a rider who scores 20 with consistent weakness across all four areas.
Pair the results with the Fuel Planner to turn the diagnosis into a week-by-week nutrition calendar, and with the Hydration Calculator to get the fluid side dialled separately from the carbohydrate side.
What to Do Next
If you have read this far, you know more about fuelling than most amateur cyclists will ever absorb. The question is whether the knowledge converts to practice. Here is the sequence that works:
- Take the Fuelling Self-Assessment. Score yourself honestly across all four pillars. The number is a starting point, not a verdict.
- Fix the lowest-scoring pillar first. One change, one week. If timing is your weakest area, set a 20-minute feed alarm and nothing else. If quantity is the gap, increase your intake by 10g/hour on your next hard ride. Do not try to fix everything at once.
- Start gut training immediately. This has the longest lead time and the highest payoff. If your target event is 8 weeks away, start this week. If it is 4 weeks away, start today.
- Check your energy availability. Use the calculator. If you are below 30 kcal/kg FFM/day, fix that before worrying about anything else.
- Build a race nutrition plan and rehearse it. Three full rehearsals minimum. Adjust after each one.
- Get blood work done. Once per year. Vitamin D, ferritin, full blood count, thyroid. Stop guessing.
The riders who get faster every year are not the ones who find a magic supplement or a secret gel. They are the ones who eat enough, at the right times, with trained guts, and do it consistently across hundreds of sessions. Fuelling is boring. It is also one of the last free speed gains available to an amateur cyclist, and the Fuelling Self-Assessment is the fastest way to find where your practice falls short.
If you want structured support building this into your weekly routine — accountability, a coach reviewing your fuelling plan alongside your training plan, and a community of riders working through the same problems — that is what Not Done Yet is built for.