Calculating Calories to Replenish during a Ride

by Chikashi

Bonking was not a concern for me until I started going on longer and faster rides.  And then, it happened one day, in the middle of nowhere, far away from base.  That was not fun. Since then, I try to take sufficient food on rides but had no idea how to methodically, intelligently determine how much food (if you can call those things ‘food’, that is) to take. And consume.

I just read Ian’s post about bonking, so I recalled my own little problem. About a month ago, I came across an article on, which recommends a way to calculate the required Calorie intake during a longer ride. N.B., the author mentions calories, but I am assuming that she meant Calories.

Based on the formula proposed by the author, I made this spreadsheet to calculate the required intake. The input fields are on the left.  If you use metric, then enter the values in metric, which will be converted to imperial for the purpose of the exercise.  If you use imperial, then simply bung the imperial values in the appropriate field.  Simplz.

Except that on a supported ride with feed stops, I have no idea what sorts of food contain what amounts of Calories. The intake is driven by ‘I’m hungry’, ‘I want something savoury’ or ‘I want something sweet’, usually followed by ‘That was horrid’.  In other words, it does not get more sophisticated or intelligent than ‘I need to refuel’. When I am consuming packaged food that I brought along, then I can see the Caloric values on the label, so it’s a bit easier.

Putting aside my utter ignorance of nutritional values, I also note that the author did not provide coefficients for slower average speeds.  I don’t think I achieved an average speed of 24 kph on the way up to Cime de la Bonette, to be honest.

The chart here shows tomorrow’s 133 km route of the Tour of Flanders sportive.

2013 Tour of Flanders Cyclo 133 km route summary

1) Start of sector (km).

2) C=cobbled; F=feed station.

3) Sector length (m).

4) Maximum gradient.

I would think that riding the cobbled sectors or the strade bianche in Tuscany must burn up more Calories than on a smooth tarmacked stretch, even when it’s flat. Therefore, I wonder if a reasonable approach is to try to consume the maximum recommended Calories to be replaced per hour.