You need more water, and don’t worry about the deficit in calories. You can never eat as much as you use. You already have too much fuel and not enough water to process it.
With only 2L of water, which is actually less if you’re adding mix to it, you will be quite dehydrated. Divided by 4 hours those 2L of mix water is only roughly 0.4 L (14oz) an hour and that’s not nearly enough.
Personally I’d say it’s too much. Taking on >500 cals/hour while riding at race pace is pretty aggressive fuelling, and I don’t think it’s necessary for an event that is “only” 4 hours. You’re going to get a good amount of those ~3000 calories from fat stores, maybe as much as half. So a more conservative 80-100g carbs per hour should be more than enough to see you through without getting anywhere near being glycogen depleted.
For a race that long I’d drop the rice cakes and just go with liquid calories and gels. Would probably have a banana or two between breakfast and the start as well, and a gel just before the start just to keep calories topped off. Hydration is definitely a concern though - are there any places on the course where somebody can hand you a bottle? If it’s a warm day then I think a highly concentrated bottle can risk GI distress, so would be figuring out where you can get extra water from, either by carrying it (extra bidon in back pocket?) or on course.
I think pushing the boundaries of how many calories you can take on is more necessary for the really epic events like Unbound, Leadville, Ironman, where you’re out there for 2-3x longer than you’ll be racing. In those events you’ve got to get much closer to fully replacing the glycogen you’re using, plus you’re at a lower intensity so your body has more capacity to spare for absorbing calories, plus fuelling for that long you can get palate fatigue and need to include some savoury and solid foods and not just gels.
Does this century have rest stops / support stations? In the couple of centuries I have done, one of which was “competitive” to meet a personal sub-five-hour goal, I used only carb and electrolyte mix for fuel. I carried gels in case of an emergency to ward off a bonk but never needed it. I started with two full bottles and carried the carb powder and gels in my jersey pockets. At aid stations / water fountains you can fill up and use the restroom in under five minutes. For a five hour century you should be able to get away with four 1L bottles, depending on the heat.
If there aren’t aid stations then I recommend seat-mounted bottles in a tri setup like you mentioned. Lack of hydration will be more detrimental than lack of fuel, but both would be bad.
For breakfast I’m a huge fan of oatmeal. Throw in a banana and keep the raisins (fiber) and nuts (fat) to a minimum. Pancakes are also a good alternative / addition.
If you’re able to drink it without GI issues, it’s being absorbed. Try drinking more. High osmo will only cause absorption issues and the first symptom = gut distress. Drink more water and see what happens.
i got this to use on a longer, solo rides where there isn’t water stops available or i didn’t want to spend time stopping. Works great and you can even attach a seat bag through the frame of the bottle holder so you don’t lose your repair kit.
Make sure you have tight bottle cages attached to it though. I launched a bunch of bottles before i got it sorted
It depends?! Last night on a flat & fast group ride I pre-hydrated and ended up drinking 4 bottles over 2.5 hours, temps were 82F / 28C. Some people don’t sweat as much or need as much water and can do that on 1 bottle.
Perfect to start the day with some rice, you could also add some chocolate powder for some sugar, as well as some greek yoghurt for some protein (big glass of milk also works).
For fuelling during. Since you mention no stops, and that you might be thirsty, I’d make it easy for yourself: 2 gels an hour, and just water in the bottles. No need to time the drinking to anything, you drink when you feel like it, and with the 2 gels an our you can just down them fast and get it over with.
Thanks all. I have ordered 2 x Inov-8 bottles, they are a flat profile and can hold 500ml each. I plan to keep them in my jersey giving me 3L of fluids total. I’ll temper down the carbs to ~50% of energy expenditure and I’ll probably try to skew it more in favour of the Iso gels, to keep the maximum amount of water available from the bottles.
Sweat rates vary a lot between individuals. If it’s hot I really suffer if I’m not drinking enough. I have sometimes gone through two 750mL bottles (in an hour) when it’s really hot in the middle of the day. I’m Northern European and not adapted to heat, anything over 25C and I’m melting. Conversely it can be 7C and I’m still wearing shorts. I’m cold adapted.
Hydration is very individual, something to be learned by trial and error. I had my biggest Waterloo experiences in racing with drinking too much, not with too little. And over the years I drink less and less while increasing the carb intake. Of course, it depends on the conditions.
For a 4 h race I would probably go with 90-100 g/h and 2 L of solution. Perhaps dilute it a little more and put some soft flasks in my jersey pockets. Furthermore, for 4h race you don’t have to feed until the last minute. And you can feed until right before start. This means you don’t have to stuff the carbs for the entire 4 hours.