Here we discuss the most critical factor in your ride on the longest day, in terms of affecting your ability to complete a 200 mile coast-to-coast route. Chase the Sun founder and experienced long distance rider Olly Moore shares a conversation with our expert personal trainer and nutrition advisor Abby Boswell, to find out how, why, and what, to fuel your body with for such an epic endeavour.
Olly: Hi Abby, Firstly thanks for taking the time to chat, and I hope this conversation can help our Chase the Sun riders prepare and succeed in their coast to coast challenge this year. Your expertise is in training and preparing for endurance events, perhaps you could start with a few words about your approach and how it can apply to a longest day ride such as Chase the Sun?
Abby: Thanks Olly! I’m a triathlon coach and personal trainer, so a focus on long events where athletes are juggling pacing, being comfortable for long durations on the bike and ensuring they’re hydrating, and fuelling, well are my bread-and-butter (pun not intended!). My philosophy is to put health, enjoyment and wellbeing first and performance will follow. In an event like Chase the Sun, most riders will be working right on the limits of their endurance capacity so the hydration and fuelling aspect is really critical.
Olly: The most common tip for success I suggest to Chase the Sun riders is to focus on their nutrition. Fuelling and hydrating over such a long ride is where the majority of people riding Chase the Sun struggle, which then I think in turn affects their performance and mentality on the bike too. Is there a kind of exponential importance of nutrition over longer distanced events?
Abby: Yes, that’s a really good tip, I agree this is likely to be one of the biggest challenges with ultra-endurance. Many people don’t realise how much they need to consume. Also not to forget hydration – in endurance sports we spend a lot of time worrying about energy intake but inadequate hydration presents a much greater acute risk: it is more likely to lead to having to abandon – and possibly seek medical help – than inadequate energy intake on a given day. Plus, you need fluids in the gut in order to absorb fuel.
In longer rides, even if you are topping up carbohydrate stores from the outset, the longer you go on, the higher the risk of energy expenditure being greater than the sum of energy intake plus energy broken down from stored sources (glycogen and fat). This can be a tricky equation to calculate because energy broken down from stored sources is dependent on your fitness profile and how hard you are working. To generalise, the fitter you are in terms of being trained for endurance, the better you are at oxidising fat for energy, although there are some nuances to this. The harder you work, the higher the ratio of glycogen:fat used and this is what is exponential. Then there is the fact that there is a limit to how much carbohydrate your gut is capable of absorbing. This is seen as a key limiting factor because if you go over a certain intensity level (let’s say threshold or FTP) then you will start to oxidise glycogen very quickly and faster than you can possibly absorb glucose so that’s a one-way-ticket to zero-energy, or a ‘bonk’.
In terms of an exponential relationship between nutrition and longer-distanced events, in fact you could argue the opposite since the longer you go on, the lower the intensity normally is and so the less energy is needed per hour. However the risk of running out of energy does increase exponentially in longer-distance events because small deficits each hour that gradually accumulate can turn into a really big deficit over the longer duration.
Olly: Eating and drinking on-the-go is, I would say, a key skill to train on the build-up to the Chase the Sun ride. Becoming time-efficient, and self-sufficient (i.e. not relying on your ride buddies to agree to a stop in order to re-fuel) goes a long way to facilitating beating the sun, by minimising stops, and pedalling while you eat. A mantra that seems to have served me well is little and often, ‘eat before hunger, drink before thirst’. Is there any more scientific approach to how much to eat, and when?
Abby: Yes, I’d say learning to eat on the bike is almost essential for a ride like this. You’re right to say eat before hunger – but what does that mean in practice? Well, you need to start nibbling almost from the outset, so you’re always ahead of the game, always ‘in the black’ with energy levels, not taking out a loan for an hour or more and then paying it off with a bigger snack. This also means you’re not taxing a stressed digestive system with a lot of bulk in one go. Eating while riding makes this possible.
From personal experience I know with more technical riding or busy roads it can be easy to intentionally or unintentionally delay your next bite, so make it as easy for yourself as possible to get food in. Strategies like opening wrappers before you set off, taping bars to your top tube or stuffing gels up the leg of your shorts where they’re in easy reach are all worth a try (I have seen people tape a literally naked bar to the top-tube, no wrapper at all but it depends on your hygiene standards!) . You can also get what’s known as a ‘bento box’ which is a small bag or case that usually fits to your top-tube right behind the steering column to stuff with tasty snacks – just make sure it’s closed before any bumpy or fast descents or your favourite energy ball can get whipped out by the wind!
In terms of how much to eat – it is individual, but also trainable. The ACSM guidelines recommend 30g – 60g of carbohydrate per hour with an upper limit of 90g. Riders need to figure out in training through a process of trial and error what amount is right for them, but start on the low and and work up. If it’s too low, you may find after a number of hours you start to experience the ‘bonk’ and if it’s too high you’re likely to experience gastro-intestinal distress – think bloating, gas but possibly also a toilet stop. If your ride is on a very hot day, you might find you can absorb less than you have in training, so take this into account, you might need to take the intensity a bit slower to balance it all out.
If you’re going with something that has a mix of carbs, proteins and fats (i.e. something that looks like food), then 3 kcal per kg bodyweight per hour is a good rule of thumb (if it were all carbohydrates, this would equate to about 60g per hour for a 70kg athlete). This is likely only half the energy you will actually use, the rest comes from fat oxidation.
Since I cautioned against getting hydration wrong, I should also explain a bit about how to get it right. A lot of riders use an energy drink, so you’re getting hydration and fuel in one, easy to swallow, easy to digest format, right? Maybe. However, for optimum rehydration, a concentration of sodium and sugars (not artificial sweeteners!) that matches the blood is absorbed most quickly.
If the sodium content in particular is too low, there is a risk of hyponatremia, a dangerously low level of sodium in the blood caused by consuming too much water with little or no sodium. On the other hand if the sugar concentration is too high, water absorption through the gut is slowed down and gut symptoms can occur too. If you separate out your fuel from your hydration by putting an isotonic drink in your bottle and carrying fuel separately, then you have a bit of flexibility to react to the conditions and how you’re feeling on the day, for example if it’s hotter than expected you can drink additional isotonic without worrying about how you will absorb lots of extra carbohydrate exceeding the threshold of what you know you can handle.
You can make your own isotonic drink with about 10g sugar and 1g salt per litre of water (the sugar component could be table sugar, maple syrup or similar) – flavour as you like but be aware that less acidic is easier on the digestive system.

Olly: What to eat is no doubt a matter of personal taste. But do you have any general considerations to recommend? For example, I have never been a fan of sticky energy gels, with a preference is to eat a mix of fruits, sandwiches, and salty snacks such as crisps at off-bike stops, and a variety of easy to handle flapjacks and similar whilst moving on the bike. Is there a magic formula of types of food to minimise the risk of digestive issues, whilst also providing the right energy mix to fuel a long ride?
Abby: For a ride as long as CTS I would say try to consume a fair amount of ‘real food’ if you can stomach it. The novelty of flavoured gels wears off pretty quickly when you’re riding all day, so plan to give yourself instead something textured and tasty to look forward to and help avoid the dreaded ‘palate fatigue’. There are also some studies suggesting a small amount of protein in your energy intake helps keep you going for longer. Gels and energy drinks are also known to be terrible for your teeth, so although your dentist will likely be none the wiser about what you consumed in a one-day event, it’s a factor worth considering if you’re using them frequently over the long-term during training and so forth. But, do pack at least a couple of gels or glucose tablets to get yourself back in the saddle quickly in the event of a ‘bonk’.
If digesting real food on the bike is intimidating, just build up to it. We now know the gut can be trained to tolerate a variety of foods during exercise, so the more you practise in training, the easier it will get.
Flapjacks and small sandwich bites made with soft white bread are a classic, some people swear by malt loaf, you could make dried fruit and nut balls if you have a food processor at home, or ‘rice cakes’ made from sticky rice or sushi rice are quite popular among cycling teams and are gluten-free – you can flavour them with pieces of fruit, cheese, ham – whatever takes your fancy. Bear in mind that the harder you’re working, the higher the ratio of carbs to fats and protein needs to be. Avoid anything to dry or crispy as this can be a choke hazard with the heavy breathing you’re likely to be doing at the same time.
Olly: So what is the theory to avoiding the dreaded ‘bonk’? Because as I have found out from painful experience, sometimes things just don’t go to plan! If so, is there any coming back from the brink? If the worst has happened, your fueltank is empty, the legs are lead and the pedals are grinding to a slow crawl… Yet it is still an apparently now insurmountable distance still to reach the coast finish. What can one do then to try and get back on track?
Abby: Ooh, good question! If your readers haven’t heard the term ‘bonk’ before in a cycling context, it’s the sudden feeling of being weak and spaced out or dizzy that happens when your muscles become completely depleted of glycogen. It is described as the body’s protection mechanism for the brain which needs glucose to function – making you stop before brain function is seriously impaired. Some athletes experience tunnel vision so it can be quite alarming and it’s not hard to imagine how difficult this makes it to keep riding! However, a concentrated dose of glucose in the form of a tablet or gel is likely to make you feel a lot better quite quickly, so plan to come home with some spares in your pocket so you’re never caught short.
The first thing to consider at the time is – if it’s definitely under fuelling that’s the issue and not under hydrating? If you’ve become so dehydrated that you feel you can’t turn the pedals, your heart-rate is also likely to be running higher than you’d expect, you will need to rest for a few hours before you can go again, simply ingesting water or isotonics at this point is not enough. But assuming you’ve been paying attention to the hydration and it’s fuelling too little that’s caught up with you, the fix is more straightforward. Take on some glucose, either in the form of a gel or a glucose tablet (these are handy for ultra endurance as they’re space-saving compared to other energy sources) The glucose will swiftly get you feeling more normal again, then consume something more substantial which will give you more sustained energy such as an energy bar or carbohydrate-rich real food, such as dates, jam sandwiches on white bread etc. You will probably need to reduce the intensity of riding to a minimum until you’re feeling better, but if you’re riding all day then don’t feel bad about a quick pit-stop, it might give you the mental and physical boost you need.
The key takeout for prevention here is to keep the intensity easy and even to avoid straying into a zone where you’re oxidising significant amounts of glycogen as this is going to significantly increase the chances of running out of steam later on. Forget town sign sprints and don’t be a hero on climbs, use your gears to get to the finish in your best possible time.
Abby has been running a full-time fitness coaching business since 2015. She is a qualified Personal Trainer and started her coaching journey with British Triathlon. Abby is based in London, providing multi-sport coaching programmes with training and event nutrition advice alongside personal training sessions.
You can contact Abby at Foundation Fit on abby@foundation.fit
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