A Geek Explores Nutrition Aspects of Cycling

As I train for my first century ride (coming up May 19) I have focused lately on finding foods that work well for long rides. By work well I mean sit in my stomach without upsetting it while giving me the energy I need to complete the ride. I’ve grown to like homemade smoothies consisting of one package of silken tofu, two bananas, and a pint of strawberries. It makes enough to fill two 20-oz bottles and I’ll have one bottle about 1-2 hours before starting the ride.* During the ride I’ve been enjoying the Clif Energy Gels.

What I needed to find out was how often I should be chowing down during a ride that will potentially last 8 hours. I found a publication that listed a series of coefficients that enable a rider to calculate his or her calorie burn rate per bound of body weight and per minute of riding based on the average speed over a long ride. The problem is that the chart started at 15mph and went up to 25mph – above my average speed based on the most recent training rides (I hit 14 mph over a 3 hour ride last weekend).  I think I will likely do the century ride with an average moving speed of 13 mph, thus I turned to Excel to plot the known coefficients versus the speeds. From the plot I could tell that the data could be fit by an exponential function and had Excel find the function that fit. It did a fantastic job.  Coef. = 0.0141 x e^(0.0922 x avg. speed).  From there I can see that a coefficient suitable for my use is 0.0467 cal/lb/min.

How do I make use of this? If I plan to ride at 13mph it will take me 7.7 hours to complete the ride. I am currently at 183 lbs. so this means that I will burn 0.0467 x 183 lbs x 60 min = 513.3 calories/hour of riding, or 3,948 calories over the whole 7.7 hour ride. The publication said to add 22 calories for every 100 feet climbed during the ride. The route for the Santa Fe Century will have 5,139 climbing feet** so I then add another 1,131 calories burned for a total of 5,079 calories for the day (almost a pound and a half of body fat, FYI).

Cyclists should be replacing those calories (in the form of easily convertible carbs) during the ride. I’ll be burning through 660 calories per hour. At a minimum I need to replace at least 30% of those, or 198 calories. The maximum recommended amount is to consume 50% of that amount, 330 calories.

The energy gel shots are 100 to 110 calories each and I plan to have one every 20 to 30 minutes after the first 90 minutes of the ride (a light breakfast and my smoothie power that first hour and a half).  This jives very well with a rule-of-thumb given to me by a cycling expert friend, to consume 100 calories every 20 minutes.

This would mean carrying 18-19 gel shots with me on the ride. However, there will be several food stops along the route providing more solid forms of food, like pb&j sandwiches, fruit, bagels, granola, etc. This should help by having more than just gel sludge in my gut and reduce the amount of shots I need to pack into an already crammed seat bag.

* 252 calories (48.5 from fat), 6g fat, 44.7g carbs, 10.5g protein, and 695mg potassium per bottle.
** (5/24/2013) Actual GPS recorded ride here.

5/24/2013 Post-Century update: How’d I do compared to my plan? I ended up riding at an average of 15.7 mph, 2 mph faster than I thought I would. It took 6.5 hours of pedaling instead of 7.7 hours and I burned 5,800 calories. Thank the wind for the extra calorie amount.