Originally Posted by
PeteHski
This is the bottom line if performance is on your agenda. As an experiment the other day I did a relatively long, unfuelled (water only) ride in Zwift (2 hours) and then hit the Alpe at the end. I felt totally fine until I got halfway up the Alpe and then I suddenly lost all my top end power. Where I would normally be holding a steady 250W and putting in 280W efforts on the steeper ramps, I was suddenly struggling to hold 200W and felt flat as a pancake. Normally I would fuel a ride like that with at least 1 energy bar or carb bottle and a couple of gels for good measure. I didn’t actually go as far as bonking, but my power was certainly limited after 2 hours riding fairly hard without carbs.
Yep. I did the 4 horsemen on zwift a few weeks back. I did the first 3 climbs at 220-240, radio tower at 300... eating only a small amount of carbs throughout.
Hit the Alpe at the 2:45 mark, which I did previously at 240-260, and completely exploded. 180 all the way up, total slog. Felt like complete poo... If I was on the actual climb, I would have been calling Uber to come get me.
But I can do metric centuries (62k) on The Big Ring at 200w with nothing but water and get off the bike feeling just like I did before I started.
I probably needed 60-80 grams per hour on the 4 horsemen vs the 20-30 I was consuming.
Edit: for shred head and others thinking of low carb.
I'm only adding carbs and heavy training for some upcoming planned rides - French Alps being one of the planned rides... Like I just said with my 4 horsemen ride on zwift, which is a good virtual training ride for days in the Alps - you absolutely need carbs and training. And the problem going from low carb to moderate or high - digestive issues. You don't want to bonk on the bike, especially in the middle of the mountains. Nor do you want GI issues!!!!
You don't want to be bonked out or pooping off the side of a cliff when 25k into the Galibier!!
For 95% of my other typical riding, limited to no carbs are required.