I’m in training for a long (c. 200 miles) endurance climbing event (c. 30,000ft elevation gain at endurance pace) that will take around 21-22 hours to complete. This insane challenge entails riding a series of 15 minute laps on the same hill (around 11 minutes up and 3 minutes down) . According to my power meter, I’m expending around 440 calories per hour. I’ve been doing long training rides, doing lots of slow hill reps at IF 0.65, which is my target intensity.
I’m still working on developing a nutritional strategy but am not sure whether I should be prioritising calorie intake over carb intake or vice versa. Currently, I’m trialling Tailwind and like the light, clean taste.
If I take on board the necessary calories per hour (c. 440) from either food or drink (or a combination of both), my carb intake feels too high and I feel full up and my appetite diminishes. If I concentrate on taking on adequate carbs (60g - 70g per hour), I don’t match my expended energy/cals.
For an endurance paced ride of this length, should I be concentrating on replacing calories or carbs? Or is there a sweet spot between the two that I’ve not yet discovered?
I’m not a nutritionist. However, I sometimes play one on the internet 
That said, this is very individual. Common recommendations are 60-90g carbohydrate per hour. I believe this is the limit of what the body can actually absorb/use per hour. 1g carb = 4 cal Thus, 240-360cal per hour.
You could do this with solids, liquids, or some combination of the two. You will need to experiment in training with your choices to make sure that you can literally “stomach” your plan.
For example, I do 1 bottle of carb mix and 1 gel per hour which puts me in the 60-90g range. I did this yesterday for a ride over 6hrs w/~3300m of climbing. I never felt hungry. I never cramped. Energy was great. Had it been hotter, I probably would have taken on some additional water.
Again, make some choices, and test them in your training. You do not want to find out on race day that your stomach does not agree w/your plan.
edit: I missed the part about 21-22hrs. Wow! In this kind of event, do people stop for meals?
Agree with KickrLin.
What food have you been eating in training? In my experience 440 kcals of carbs would be a lot LESS filling than protein or fat.
Also, I’m no expert, but I don’t think you need to worry so much about replacing the exact amount of calories every hour. I’d just focus on the g/kg of body weight per hour of carbs and mix in other foods (protein and fat) based on what real food you fancy eating during the day
I’ve never done an event of that length. However, maybe @brendanhousler will chime in. I believe his recent ride/race was a 300mi gravel ride. 
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For the purposes of a 22 hour race your body effectively has an unlimited supply of fat. Even if you’re <10% bodyfat, you still have plenty. 440 calories per hour is 9,680 in 22 hours. Let’s assume half of that comes from fat, half from carbs, that’s 4,840. A pound of fat is 3500 calories, so that’s less than 1.5 pounds of fat, even Mo Farah has that much to spare.
So from a pure nutrition perspective you need to focus on the carbs (caveat - 22 hours is a very long time and you may well crave some variety and some “normal” food rather than just sports nutrition products). And you don’t need to take on 440 cals/hour, since as above a decent proportion of the calories will come from fat. Furthermore, assuming you’re fully fuelled when you start the race, you’ll have 1500-2000 calories of glycogen in your muscles and a bit more in your liver. If we assume the 50:50 fat:carb burning ratio is correct (could be higher or lower for the individual) and that you had 2000 cals of glycogen stores, then you’d “only” need to take on 2,840 calories of carbs during the race, or less than 150 per hour. In practice there are a few estimates involved here so you don’t want to cut it too fine, but something in the region of 250 calories per hour should give you enough of a buffer and is an amount that you should be able to absorb without developing GI or other issues.
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Thanks @KickrLin. So you’re prioritising carbs over cals? 60-90g carbs per hour is my understanding too.
During the event (it’s self-supported), you can stop as often and for as long as you want/need.
I’ve been breaking down the training rides into a series of stages and laps on the hill where the event will take place. One lap = once up and down the hill (c. 15 mins), one stage = six laps (90 mins). 10 minute rest at the end of every stage to take on more food and drink. One 750ml bottle every stage. I’ve been experimenting with the strength/carb content of my drink (and trying out a few different brands), and eating a quarter of an energy bar every descent (every 15 mins). I cut up energy bars into quarters and carry enough in my jersey pocket to last a stage. The ones I’ve settled on for (for taste, texture, nutritional values, etc.) are Wiggle energy bars, Veloforte bars and Chia Charge bars (all UK brands).
Good answer @cartsman. Very informative. Thanks!
disclaimer: i only made it 200 miles on gravel cause di2 battery died.
carbs if you can handle it! Not to push this product, but Science in Sport BetaFuel has 80g of carbs in one packet, so you get almost ALL the carbs your body can absorb in one hour in a bottle. It’s amazing, it makes nutrition almost brainless for some hours.
Then it’s eat whatever you can digest. 22h is a long time.
Best of luck!!!
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Assuming you can stash as much food as you want at the rest point, I would strongly recommend having some variety in there in case you need it! Even the best tasting bars will get pretty boring after 20 hours. Personal favourites include Haribo (the tangy flavours that are crusted with sugar are the best) and nuts, either salted or honey roasted. A friend swears by peanut butter and jam/jelly sandwiches.
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It’s not so much prioritizing as it is I never thought about using calories. I had always read or been told XX carbs/hr.
Definitely experiment. As for the bars, they work for me as well. It’s also nice to chew on something every so often. I’ve been doing gels lately since it’s less bulky. With something like a Cliff bar, I typically do 1 bar and 1 gel per hour carrying only water. Otherwise, breaking the bar into quarters or thirds to complement your carb drink is a good option as well.
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Yep, support van strategically parked, packed with a variety of food and drink.
I agree with the thrust of what people have said here.
Worry about carbs on the day, to fuel you enough to get through the event. I’ve done (or nearly done) an everesting challenge, and one thing I now wish is that I’d taken more energy drink and gels, because boy, “real” food was hard to chew and swallow between laps. Even rice cakes were like eating cotton wool.
Worry about calories the day after, with a delicious and massive meal of your choice. One of those times when pizza and beer is probably not just excused, but called for.
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Good answer @martinheadon, thanks. Good point about carbs on the day and calories the day after.
Agree wholeheartedly about chewing food between laps. I’ve done several half Everests as part of my training, and towards the end of a couple of them I found it so hard to physically chew - even though I was only trying to eat a quarter of a bar. It was as if my jaw wouldn’t work. Mind you, I’d been having a quarter of a bar every 15 minutes for the previous 8-9 hours, so maybe it was just fatigued 
On my next big training ride, I might try food and energy drink earlier on, then switch to gels and energy drink towards the end.