I’d taken a bit of a break after a fairly disastrous ride into work last week, forgoing even my usual Sunday long ride despite it being a only few short weeks until Lap The Lough. Sometimes you just know, right? So this morning I thought it was worth another shot at my 25 mile commute route, and I also took the chance to experiment with fuelling a little ahead of the big event.
Firstly, the ride was fine and I was feeling my normal self again, so that’s a relief. The conditions weren’t great either, with blustery wind in the hills at the start, followed with a strong headwind along the coast and then proper actual rain as I got into Belfast. I managed an average of about 18.0 mph until I hit the city centre. That’s down a little, but as I said it was into a fierce wind, and I did get stuck behind a slow cyclist (on a fast bike!) for a stretch along the A2 where it was too busy to pull out and pass safely, so I’m not too concerned.
The fuel experiment was the most interesting aspect though. Conventional wisdom has it that hard cycling will burn up to 60g of carbohydrate per hour, but I wanted to see how much I’d burn personally so I could better judge how much food to carry with me on Lap The Lough.
Here comes the science part.
Breakfast consisted of about 30g of carbohydrate from some toast and a small glass of energy drink. This lasted about 30 minutes as I made my way towards the Beltoy Road, when, as expected, I had a bit of a”bonk” (stop sniggering, you know what I mean). A further 50g of carbs from a rapidly snarfed gel pack lasted me the rest of the ride and I began to feel just the start of another drop in energy with just a couple of miles to go.
So 80g of fuel lasted me about 90 minutes of quite high output, giving an approximate rate of consumption of 50g/hour. That’s right in the ballpark conventional wisdom suggests. Now this is a much higher level of effort than I could sustain for the 90 miles of the Lap The Lough route, but it’s an anchor point to work from, and suggests a maximum requirement of 275g of fuel for the event if I match last year’s average pace. I’ll take more than that, of course.
Science is fun. Also, useful.
I did 63 miles with an intake of approx 60g CHO on top of a massive 60g CHO oaty toasty breakfast. It took me a dog’s age, but would it be fair to say that a combination of miles/fitness/speed is a better way to measure? More difficult, but better perhaps.
Aaaaaanyway, 120g CHO = 60 miles approx. I don’t measure in bonks though, I measure in blood glucose levels… try to keep above 5 when cycling, to avoid potential embarrassing hypoglycaemic comas on the way.
(for diabetic pedants, I know 5 mmol/l isn’t a hypo, but I keep it above that to avoid unforeseen drops, y’see?)
You’re absolutely right Phill, everybody is different and the amount of fuel you use will depend on the level of effort you have to put in to maintain a given speed for a given distance. That’s why I did my experiment, to see how much I needed personally.