Only solids on the bike during full Ironman?

I’ve been doing full IM races for the past 10 years and I’ve been very successful on the swim and bike but have always had major GI issues on the run. My nutrition on the bike has historically consisted of Ucan drink supplemented with gels and that combo has been successful while I’m on the bike but after about the first mile on the run, I begin having major GI issues to the point that I’m on the verge of puking. I’ve even experienced diarrhea on two races. I rethinking and my nutrition on the bike and wondering if anyone has ever tried having only solids with electrolyte drink on the bike. I completed a 86 mile MTB race two years ago taking in only Nature’s Bakery fig bars and electrolyte drink and had absolutely no GI issues and never bonked. But with no run following the race, I can’t decipher whether I can take that approach in a full IM. Anyone every tried only solids on a full IM? Any success stories out there from other racers that have overcome this?

This is interesting, and makes me think there is more to it than simply what you are taking in on the bike. A couple follow-up questions:

Do you train using the Ucan drink? What kind of nutrition do you take during your long training rides and brick workouts?

What is your nutrition like leading up to the race? Do you eat the same things a few days out and especially the night before as you do before big training weekends? Is your breakfast the same as it is before big workouts?

I use a mix of solids and liquids on the bike and have had good gut performance in two IM’s, but I think it’s less about what you are doing and more about trying to keep it consistent during training. If I have big weekend rides/runs, I will try to have the same dinner the night before as I would before race day. Same with breakfast. And a day or two before the race I will start to reduce fiber in my diet (typically eat lots of raw veggies and a high fiber diet. I reduce this before race day)

There is certainly a school of thought that says “eat your calories, drink your electrolytes / hydration”.

I’ve personally never done it, but it is worth experimenting with. You might want to consider a “long day” of training to experiment…do a 5 hour ride using the solid fuel strategy and then do a 2+ hour run and see how you feel. This attempt should be preceded with sufficient “stomach training” for you to get used to that much solid food on the bike…and of course needs to be properly timed in your training cycles.

I have completely cut Ucan out of my training and racing nutrition plan because I assumed, it being my largest source of calories and carbs on the bike, that it was the source of my GI issues. This is why I started this quest to find the best nutritional plan for myself moving forward. I eat normally coming into a race (I follow a paleo / higher fat diet) and load up on good carbs the night before and oatmeal & banana that morning of any race.

Like I stated, I’ve done long MTB races with all solids and had no issues and in fact, it’s been very successful. I’ve done 100+ mile rides with all solids as well. But there’s no marathon after these rides so it’s hard to say whether only solid foods on the bike during an IM will be successful. Like @Power13 stated, I guess I’ll just have to test with a simulation and see how I respond. But I was hoping other athletes would have success stories giving me hopes that an all solid bike nutrition plan can be successful because I hear and read is “liquids on the bike”.

I see. I think it may be hard to pinpoint a single source of GI distress, but it is possible that it is UCan. But I think the most important thing is that this is trainable- trying a long simulation workout is a great idea. But I would suggest that every brick workout you do, you try to follow race day fueling strategy. So even for shorter stuff, do solids on the bike and run and see how you feel

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When you say major GI issues, are we talking that once you start running you NEED to go. Or is that you need to constantly go during a run, or pain, or something else?

Put simply, your gut doesn’t care as much about solid vs. liquid with regard to kcal or electrolytes.

It cares about resultant concentrations and consumption rates.

  • Kcal consumption rate. (kcal/hr)
  • Kcal density (kcal/L) or concentration (grams/L, where grams is grams of carbs, since that’s ideally all you’ll consume)
  • Osmolarity (conceptually, molecules/L)
  • Glucose consumption rate. (grams/hr)
  • Fructose consumption rate. (grams/hr)

Whether you manage all the above via solid or via liquid, your gut won’t care much. Gut limits for all the above might be slightly lower if the “solids” approach is undertaken. Probably only very slightly, assuming that your solids approach contains no fiber, no fat, and no protein. Maybe more than slightly if there is substantial fat, fiber or protein in your solid food choices.

Perfect example…I did IM Boulder in 2019 and had a great swim and bike. I started the run, feeling really good for about two miles, and then my stomach started cramping. It was all stomach with nothing major happening in my lower GI. At about mile three, I had to stop running completely because I thought I was going to puke and then it was a death march for much of the remaining run. I stopped eating completely hoping I would digest everything in my stomach and then I could resume taking in nutrition but by that point I had lost focus on the race and was in survival mode. I did keep driving water throughout this entire process because I didn’t want to compound the issue with dehydration.

I see.
It really sucks.

IM are no joke. They strain your body in ways nothing else can.
Do you have this problems when you do your normal training runs?
Or bricks?

This could be a pacing issue, as well…as the old saying goes, there is no such thing as a great bike if you fall apart on the run. And too high a pace on the bike can definitely lead to stomach problems on the run…if you are going too hard on the bike to digest your intake, it can show up pretty quickly on the run.

This is the huge challenge of IM…figuring out proper pacing vs. nutrition. I never successfully did it in a full IM, but managed to figure it out for 70.3’s. A full is just a different beast altogether…

You bring up a good point @Power13. I do know if an athlete pushes too hard on the bike that the overexertion can shut down digestion and then the athlete’s bike nutrition sits in their stomach until they come into T2. Then the GI issues start because of gut rot. Something to think about.




Do you take the same supplements when training and doing brick runs?

Maybe an allergy to something you are taking on the bike?

I know that sometimes I get craps and gi issues AFTER a long run where I went out too fast or didn’t had proper nutrition.

I always did take down the same nutrition and don’t think I have any allergies. I’m on a mission to solve this because I can’t take another disaster run after a solid swim and bike. So if I have a breakthrough, I’ll post it here and hopefully we can all glean something from my n=1 results.

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Best of luck.

This is not a nice problem to have. Specially if you don’t have the same issues while training,

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Are you trying to KQ or just put together a solid overall performance?

If the latter, I’d suggest potentially “burning” a race and riding a VERY conservative bike leg and seeing how that plays out on the run. Worst case scenario is you have “slow” bike (relative to expectations) but a strong run, which will still net you a faster finishing time.

You can build up from there…

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I’ve had a lot more success with fluid only for IM with the recent reintroduction of a couple of maurten caffeine gels for the run.

I used to have real issues during IM’s but fluid only has erasures this. This includes for pre race breakfast. If there is nothing in there, there is nothing to digest ( no blood flow requirement) and nothing to come out.

It sucks a bit and I would love to be one of those guys who can eat a snicker whilst running. But I’ve accepted that’s not me and as I want to be competitive this is going to be the way I need to go.

On the plus side, whilst going down this route, I’ve found it much easier to get c100g carbs down per hour on the bike and 60 or so on the run. Which is as big a performance gain as not having a dodgy stomach I reckon!

And it makes a post race pizza, burger and beer even better!

So if you don’t mind me asking @nicco, what liquid are you using on the bike?

No probs at all.

I’ve varied from maurten and sis beta. Can take either equally as well although I find maurten slightly harder to work with as it clumps / thickens a bit more easily I find.

For training I tend to just go with sugar, water and dump some electrolytes in there for flavour and the obvious other benefits.

Come race day, I have a large front bottle (giant trinity) that I fill up from an aero bottle on the frame and also from slightly over concentrated bottles on the rear. So I have about 3.5 litres on the bike and I can add water as needed. Few gels for caffeine on the bike (love the maurten gel texture) and that’s about it.

For ‘breakfast’ I will have a strong coffee to help get things moving and start the caffeine train. But otherwise I’ll have a small energy bar or a small white plain bagel. I’ll take an energy drink into transition and drink that plus a gel before the swim.

I’ve come to the conclusion that IM is basically 24 hours of very little food for me, with last meal mid afternoon the previous day.

Then cross the finish line and eat everything that is in sight.

But everyone is different. I know pro IM winners who have a couple of snickers on the bike and could stomach dozens of gels in a race. Ability to absorb carbs is a big differentiator for performance. Pro’s are basically all great at eating.

How much were you drinking during the last hour of the bike leg?

Maybe front load the consumption of liquids and ease off before the run?