How do you calculate carb use per hour for tempo, SS and threshold?

I’m sure it’s variable for us all, but is there a way to do this roughly?

Is there a difference?? I consume as many carbs as I can process without gi issues. Tempo, ss, treshold. All the same :relaxed:.

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For all workouts I do something really simple. Look at the estimated calorie burn:

That one burns 1313 calories. I take 50% of that, about 650 calories, and I put 6 bars into my jersey pockets. Lately I’ve been using fig bars and granola bars, they are conveniently 90-100 calories each (roughly the same as a medium-large banana). And my hydration mix is about 50 calories.

My Garmin reminds me to eat 100 calories for every 200 calories burned.

I usually have a meal planned after every workout.


@AlexWild answered my question on Instagram one day about this exact thing.
It’s been working for me so far, you take the total calories projected to burn on the work out. Divide that number by four and that is how many grams of carbs to “try” and take in throughout the whole workout.
I personally can consume up to 120 g of carbs an hour, the higher end of intensity I use more liquid calories but with tempo efforts I could eat pretty much anything and not have stomach issues.


Fig bar math for Alex’s method on my 2 hour endurance ride example above:

  • 1313 calories to be burned / 4 = 328g of carbs
  • 328g / 38g/fig bar = 8.6 fig bars

Without the hydration mix, here is comparison of two methods using my 38g carb / 100 calorie per fig bar as the carb source

  • 6.5 fig bars using the 50% cal burn - to - calories of carb rich food source conversion
  • 8.6 fig bars using the 25% cal burn - to - grams carbs conversion

close enough for me.


That is definitely close enough :joy:

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the math changes when I pack the 29g carbs per granola bar (= 11 granola bars on the 50% method)… I like to toss one of those in my pocket to break up the fig bar monotony.


programs like XERT will give you the estimated calories/carbs/fat grams burned during a ride.

You can estimate your distribution from the research based on % vO2max

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As @bbarrera mentioned, looking at the expected kJ from the workout is a great starting point.

For me, there is no way I can consume enough carbs to completely cover the workout during the workout, and higher intensity workouts even 50% is a stretch. A SS session for me burns 950-1050 cals/hr. So instead I take in as much as I can; I can get in about 100g (400 cals) carbs/hr using liquid. I try to have 80-100g carbs a few hours before the ride and a 200-400 cal recovery shake to make up the difference (bigger shake after bigger rides).

Remember even at SS, there’s going to be SOME fat burning contribution, so you don’t necessarily need to balance cals burned with carbs consumed; cal in = cal out with a carb focus is what I go for.

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No difference.

Only difference could come from maybe being physically able to consume LESS for threshold due to increased risk of GI distress with higher intensity training.

FWIW: There is no evidence that fueling only the carb-burn from the training session itself, during training, should be the goal of fueling training.

If you can exceed carb-burn with your consumption, I say: do it, for any session >2 hrs and at least z2.

You’ll just be more replete with glycogen for your next training session.

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I keep it simple and along the lines of recommendations from CTS and FasCat:


Initially I found the TrainerRoad suggestion of 60-90g/hour to be excessive for shorter 1-2 hour workouts, and good for 3+ hour rides. But over time it seems I’ve come around and am eating at least two fig bars per hour, so thats 76g/hour. Really helps with post-workout recovery especially on all the ~2 hour mid-week workouts.

Its all personal, and I’ve experimented a lot. In the end I found targeting on-bike replacement of 50% calories burned has worked very well for me on rides up to 5-7 hours. On longer 8+ hour rides I start by using carbs in water bottles, and then switch to eating more real food. in general the longer rides require more aggressive consumption of carbs on the bike.

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