Like many of you, I’ve been experimenting with my carb intake during rides and races. My Socials and Podcast feeds tell me cyclists can down 90–150 grams of carbohydrate per hour. This is a lot. It is many more carbs than I recall ingesting when I raced my bike for a living in the 90’s doing 5-6 hour races on one rice pudding tart (a ubiquitous Belgian treat) and three water bottles.
I’ve tried 80g/hr, 100g/hr, and even 120g/hr during several rides. All three amounts gave me some gut pain - fortunately not on the bike, but afterwards. Fortunately, it was nothing more than pain:) and it went away by the time I went to bed. The question was, why? Was it too much carbs, was I not “carb trained”? It took a nutrition “fail” to point me in the right direction.
I was in a gravel race, Kowtown in Kremmling, doing the middle distance (54mi) event known as the Cow (the long distance being the Bull) where I only managed to ingest 2 gels (2x 40g) over the 3 hour event. I just kept forgetting to eat. The odd thing was that I had plenty of power and never bonked during the event. This got me thinking. Do I need the 80-120 g/hr like the Big Boys and Girls (WT riders) were taking, or did I need less? This mishap in Kowtown was making me think I didn’t need as much as I thought or was being led to believe by all the Socials…
My epiphany was this, World Tour riders need high levels of fueling because they are producing more energy than I am. It’s not a matter of effort. If a WT rider’s effort is at x watts, mine is some number of watts that is less than x. Thus, to fuel your watts you need y carbs. Fancy math translation: the amount of carbs we each need is related to our individual power output numbers. It is not based on an effort level, meaning carbs don’t fuel a hard effort, they fuel a literal power output.
Before figuring this out - I know it sounds obvious when you see it in writing - I was thinking more along the lines that my carb needs were related to effort. If I was in a race, I’d need the same amount of carbs as a WT rider because, like them, I was doing a maximal effort. The reality is, I only need the carbs to fuel the watts I produce. Carb intake above this and they become a negative. Why? Why not just over fuel and play it safe? Nope, one of the things I experienced while testing the 80/100/120 carbs/hr was that I would get blocked (just a blah feeling that I couldn’t push it and I had less energy). The reason is simple. Your body has to deal with the excess carbs. Basically, my body needed to dilute what I was putting in. This took blood and energy away from going fast (and toward fixing what I had done to it).
My epiphany and new strategy aligns well with the science. The current science has a fancy equation to help figure out the amount of cabs one needs. It is:
Carbs/hr = coefficient (how well the body processes carbs)) × body weight (kg) × relative intensity (watts)). Here’s an example:
Rider’s Body weight: 74.8 kg with an FTP of 309w:
-
Low end (0.5 coefficient — conservative fueling): 0.5 × 74.8 × 0.85 = 31.8 g/hr
-
Mid point (0.6 coefficient — solid baseline): 0.6 × 74.8 × 0.85 = 38.1 g/hr
-
High end (0.7 coefficient — aggressive fueling, longer/harder effort): 0.7 × 74.8 × 0.85 = 44.5 g/hr
My numbers are very close to this example and confirms the conclusion I drew from my Kowtown race. I don’t need WT amounts of carbs / hr! The 40g/hr were actually inline with my current capabilities.
The takeaway: It’s not that we should eat less for the sake of it — it's that our fueling should match our physiology, not someone else's. Know your FTP, know your race weight, and run the math. Ride at your wattage, fuel for your engine. Leave the 120g/hr protocols for when you arrive on the World Tour:)
::DP