Triathlon Bike Nutrition/Hydration

I’m working on dialing in race nutrition/hydration and was hoping others may want to discuss. I’m 5’9”, 150lbs and primarily do mid-distance triathlons. Based on some previous posts in another thread on the forum, I’m going to experiment with upping my carbs, calories, and liquid intake per hour (to 100g/400cals/~30oz) in an effort to set myself up for a stronger run off the bike.

While I understand race day nutrition is highly variable among individuals, I’d love to hear others’ nutrition/hydration strategies on bike portion of triathlon. How many cals/carbs/oz per hour do you shoot for? If you use all liquid nutrition in the bike, what’s your go-to product?

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I don’t count the calories but I do consume 2 gels (Hammer Gels) an hour and 30 oz of Skratch Labs Lemon on the bike with water to fill in fluid intake. I keep the 2 gels going on the run and just use water or Gatorade. That probably is roughly 300 - 400 calories and hour.

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I use Hammer perpetuem caffe latte and go for two scoops per hour (270 cals, 54g carbs) augmented with a 21oz bottle of water per hour.

edit: added nutrition info

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I use Carbo Pro, which can be added to any preferred sports/electrolyte drink. It’s mainly flavorless unless you are drinking like 3-4 scoops alone then it is mildly sweet. I usually prep my mix of 3 scoops of that plus 1 scoop gatorade in a 20 oz bottle per hour. I might be able to ingest more liquid than that, but since I am racing xterra, I’ve found that I have to try hard to drink that much.

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Hey, sorry for the long time to reply, I was putting my strategy to the test at the Cozumel 70.3… and then I enjoyed the beaches and snorkeling for a week. :slight_smile:

I haven’t done a lab sweat test to determine my needs, but I used the questionnaire from Precision Hydration to estimate it, and then I’ve refined it on long rides and at events.

What I can tell you is that based on what I see other people do, versus what I seem to need, I am probably on the tippy top of high volume, salty sweat. Part of that is probably my weight right now (210lbs), which could use some adjustment but it will take some time to get back to what’s been my best racing weight (185lbs). But even when I was lighter, I put out a lot of sweat very easily.

Here’s what I can say after last Sunday: it’s really hard being a heavy sweater in a hot, humid race. It was so hot and humid (and honestly, even starting the race fully hydrated was challenging, because you sweat a lot without doing anything!), I went through: 1- my 28oz BTA bottle, 2- two 24oz bottles in my triangle (all of these had 10g carbs and 166mg sodium per 4oz liquid), 3- one package of Clif Bloks, 4- three bottles of Gatorade handed out on course (not Gatorade Endurance unfortunately), 5- a bottle of water handed out on course that I didn’t drink, but poured on myself to cool down. I was on course to do a bit better, like 2:50 or so, but I have some lingering fit issues and couldn’t hold my TT position the whole time.

I ended the bike starting to cramp hard, and I spent the first few km of the run walking while taking salt pills with water at the water stops. After I’d gotten 4-5 salt pills in (so 800-1,000mg sodium), the cramps started to ease up and I felt better. If I’d been able to get more of that sodium on the bike, instead of drinking the relatively low-sodium Gatorade, I would have been in better shape, I think.

In the future I think I will stick with my first three bottles as described (I use EFS Pro, 1 scoop per 4oz water), but I will have some of Precision Hydration’s high-sodium tablets to add to water I pick up on the course. I was also hitting about 80g of carbs per hour, and I have no complaints about that but I might throw in a second package of Clif Bloks to bring me up to 95g/hr.

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I’m signed up to do my first 70.3’s this year - doing a small one in Napa, then doing Santa Rosa and CDA. I’ve been road racing the past seven years and have gotten very comfortable nutrition wise on the bike… however when I combine swimming, which I seem to tend to ingest water doing (despite a decent swim background) I tend to have side stitch / stomach cramping issues while riding and especially running. Honestly outside of learning transitions, it’s the thing I’m most nervous about as I’m relatively comfortable with the distance/time/my fitness. I’ve heard @Nate_Pearson numerous time mention nutrition is the fourth discipline - Nate I like your planning heavy / OCD style of nutrition planning. I’d love to hear your thoughts hear or on the podcast about how you’d approach/ think about 70.3 fueling. On my bike I tend to be an under fueler while training, I think with Tri this year training my gut is going to be a big part of this…

Make sure you can do this in training before you try it on race day, but here’s what I’d do with carbs.

Load 8-10grams per kg of body weight for 2 days before the race.

400g morning of the race.

100-120g per hour on the bike and run.

Note: if you just try this on race day without prepping you’ll likely get diarrhea. This could be built towards in training and practiced at low priority races.


Thanks Nate, now I just have to learn to fuel while running, any random Half Marathons I’ve ever done I’ve just fueled before, but know for this I’ll need to be fueling as I go. I see some serious side cramp training sessions in my future. See you for the upcoming road season!

We are almost exactly the same weight and height. I usually shoot for about 300 cal per hour and carry enough additional energy to add if I feel good.

For a 70.3 I typically do a gel before the swim start (100cal) and another in T1. On the bike I carry about 1.5 Liter tailwind for a total of 600 cal. That I know I can stomach easily and it lands me almost spot on at 800cal in T2 after about 3 hours. Depending on how hot the race is I take on additional water in aid stations and might pop a salt tab or two. If I feel good I’m having another gel or two on the bike. Recently I’ve been more hesitant to take on more because I have had races where I felt weirdly full in T2. If I don’t I’ll have a small running bottle with about 150-200 cal worth of tailwind ready in T2 to take with me in the run for first km‘s.

The run is very dependent on weather conditions, but here I’m more concerned with hydration, usually taking a sip of water at every aid station. I often use Gels as a strategy to keep my mind occupied, e.g. I plan on having a gel at k15 as a small intermediate goal. If I feel the bonk coming I start drinking coke and Red Bull in aid stations and hope that it will be over soon.

For my next race I want to experiment with caffeine. Inspired by @Nate_Pearson I want to avoid caffeine all race until early in the run and then get serious with about 500-600mg to get through the run at full chat. I’m considering SIS hi caffeine gels (150mg each, one a few minutes before T2, another early on the run plus caffeinated water for another 200-300mg in T2. Could be great. Or I might soil myself, who knows :joy:


I’m 6’4" and at IMFL this year I was 195ish pounds. (193cm and 89kg). Anyways my strategy was to take in 100g of carbs an hour on the bike, and 75g of carbs an hour on the run.

For the bike I experimented with a maltodextrin and table sugar mix. (2/3 to 1/3 ratio) and that seemed to work quite well for me. I was able to get around 250g in a water bottle without it getting too thick or nasty, so I had two water bottles behind my saddle as my planned time was 5hr. I also put some electrolyte mix in there as well, mainly using sodium citrate. I marked off on the bottle where the levels should be for every hour on the bike and I did a great job hitting those marks. Then between my areo bars I had a bottle for just water that I was able to refill from the aid stations.

The big advantage I found with that strategy was that it was SO DAMN CHEAP!!! I bought a 25kg bag of maltodextrin for around $80, and table sugar is not all that expensive either, and used that instead of gels during pretty much any training ride over an hour and I still have many many kg left over. (25kg is 100,000kCal or 1,000 gels. At $1.50 each, it would cost $1,500 for the same amount of energy). This in turn meant I was really well fueled for my training, which meant good training, I was extremely tolerant of that mix, and I saved a boatload of money.

EDIT: On the run I did gels for the race and the 2-1.5 months or so leading up to the race just to reacquaint my body to them. For the rest of my run training I took my bike mix to save that $$$ since I already knew I could tolerate gels on the run.

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Naive question here, how can you determine if you are past the carbs/hour your stomach can handle for an hour or 2 hour trainer ride? Just wondering how quickly the stomach issues appear/if practicing/fueling like that for those shorter duration rides can hide the fact that you can’t handle it during a long race day.

I could handle more than I expected during my first run at high carbs during 2hr Boarstone (90g/hour). Does bumping up carb intake make sense, or do I need to confirm on something longer like 2.5hr Ochoco next weekend before upping my intake?

Thanks for laying this out - super helpful - When does fueling no longer make sense/ when should you stop fueling on the run - I’d imagine inside the last 45 minutes you’re not able to use much?

It depends how your day went, if you’re short on fuel you may bonk anytime, even within the final 45 minutes. If your day went well, then yes, it doesn’t make much of a difference. Still, if I feel good I basically keep eating, if it doesn’t help my race it helps recovery.

Gut issues can manifest very quickly if you go past what your stomach can handle, particularly if exacerbated by heat, dehydration, race day stress, etc. For that reason I’d take a different angle on nutrition to some of what’s been suggested above. I would work out how many calories you think you need, including a suitable buffer, and use that as your target. You might be able to handle 100 or even 120g/hour, but if you don’t need that much why put that extra load on the body and take the risk of giving yourself problems?

The way I approach it is:

  • Estimate total calorie consumption for the event. Swim is a bit of a guesstimate but if you have a PM for the bike and a running watch that is properly calibrated with your weight and HR zones you should be able to get a reasonably accurate number. Let’s say it’s 1000 calories/hour for a 5 hour finish time = 5000 calories
  • Estimate how many of those calories come from carbs. E.g. if half your calories come from fat burning then you’re burning 2500 carbs
  • Assuming you’ve carb loaded reasonably well you should have glycogen stores of ~2500 calories in your body at the start line
  • If all those estimates are spot on, and you wanted to cross the line just as you emptied the tank, you could do the race on water alone! Clearly that’s a terrible idea, you don’t want to be totally emptying the tank for both performance and recovery reasons, and your calculations are likely to be off somewhere. So let’s add on 1000-1500 calories to give you a decent buffer, that’s 2-300 per hour or 50-75g carbs/hours. That should be plenty enough to allow for any wrong assumptions (e.g. if fat only contributes 40% of your calories) and allow you to finish with some reserves.

Calculation will be different for everybody depending on weight, power, estimated finish time, etc. But a 70.3 isn’t actually that long an event, and I suspect very few people actually need to be taking on 100g carbs/hour or more. Nate might be at an extreme end of the spectrum as a heavy guy with a high FTP who will therefore burn through a lot more calories. He’s also somebody who has a lot of experience taking on very high amounts of carbs while racing and knows he can handle it (though I do think there is often a big difference between what you can handle on the bike and what you can handle on the run), so for him it may be pretty low risk taking on that much.

If the race is something like IM, Leadville or Dirty Kanza and you’re going to be out there for 8, 9, 10+ hours, then it’s a very different proposition. Those races are long enough that your glycogen stores need to be eked out much more carefully, which means you need to be much closer to replacing all the carbs you’re burning during the race.