Open water: 12 weeks of magnesium glycinate and HRV data

Why my centuries fell apart at km 95 — and what changed.

I started cycling seriously in 2020 at 39 (illustrative — the athlete in this story is fictional). I picked up a road bike during the pandemic and rode my first century the next year. By 2022, I was riding two centuries a month, sometimes three. And every single one of them ended the same way: somewhere between km 90 and km 100, my power dropped off a cliff and I limped home.

I tried more food. I tried more electrolytes. I tried a coach. None of it solved the bonk. What finally did was reading the Unived Buyer's Guide page on a recovery day and realising my entire on-bike fuelling plan was wrong.

The math I had been doing wrong

My carb intake on the bike was around 40 g/hour. I thought that was fine — it was what every gel I had been buying delivered. What I had not understood was that the literature is clear: for rides over four hours, carb oxidation can go up to 90 g/hour, but only with a dual-carb formulation that engages both glucose and fructose pathways. Single-source gels max out around 60 g/hour. I had been under-fuelling by half.

I switched to Elite Gel-180 for any ride over three hours, with Gel-100 in the first hour while my stomach was still happy. I started using Hydration Mix instead of plain water. I added Salt Capsules for the long stuff in summer. The first century after the change, I finished at the same average power as I started. The first time that had ever happened.

I am not faster than I was. I am not winning anything. But I finish where I used to fall apart. That is what changed.

By the numbers

A year of riding

Next year I am attempting Mumbai-Goa over two days. I have a fuelling plan now. The plan is the difference.