Week Five: 1,000 Miles Down, and Making Friends With Zone 2
It's Friday of week five, and the numbers have ticked past two thresholds I'd been half-watching: over 1,000 miles ridden, and over 12,000 metres climbed. Written down like that it looks like something. Ridden one session at a time, it just felt like another day on the bike.
Today's session was two hours in Zone 2, and since that phrase crops up a lot in a training plan without explaining itself, it's worth explaining for those that are not familiar, it's also the best excuse I have for why I spent two hours this morning looking like I was about to go skiing indoors!
So what actually is Zone 2?
Think of your body as having two different engines for producing energy: a fat-burning one and a sugar-burning one. The sugar-burning engine is powerful but has a small tank, it's what kicks in when you sprint for a bus or grind up a short, steep hill. The fat-burning engine is the opposite: much less punchy, but the tank is enormous, because even a lean cyclist (I’ll be one at some point soon) is carrying tens of thousands of calories of fat around with them. Zone 2 is the effort level — roughly 60–70% of your maximum heart rate, where you're leaning almost entirely on that second engine.
The tell-tale sign is that you can hold a full conversation while doing it. Not gasped sentences between breaths. An actual chat. If you can't talk in full sentences, you've drifted out of it and into the sugar-burning zone, which feels more like "training" but isn't what today's session was for.
Here's the part that makes it interesting rather than just easy: riding, repeatedly, over months, is what teaches the body to get better at using fat as fuel in the first place. It grows more of the tiny cellular power stations (mitochondria, if you want the technical word) inside your muscles, and more of the blood vessels that feed them. None of that happens in a single ride. It's closer to slow-cooking than searing… nothing dramatic happened in my pan today, but the flavour that builds up over hours is the whole point. Ride 21 stages back to back and the day that matters most isn't the one where you went fastest in April, it's the aerobic base that lets you get out of bed on day 15 to do it all again.
Today's two hours, on the Wattbike
Other commitments meant the road wasn't an option today, so this one was done indoors on the Wattbike, which brings me to the getup, because I imagine it raises a question or two if you'd walked past my garage this morning.
Yes, those are sunglasses, worn indoors, at 11am, going nowhere. That's not a fashion choice, it's to stop my eyes drying out and getting irritated by the enormous fan I point at myself to stay cool for two hours of steady effort with none of the natural airflow you get outside. And the headphones are doing double duty: music to keep two hours of the same gear and the same wattage from feeling like four hours, and enough noise cancelling to drown out said enormous fan, which up close sounds less like a gentle breeze and more like a light aircraft preparing for takeoff.
The bit that's hard to say out loud
Twenty-one stages of Tour de France history, back to back, in 2027, still feels a long way off from where I'm sitting today, if you put me on the start line tomorrow, I couldn't do it. Not close. That gap between where the fitness is now and where it needs to be is exactly what the next ten months are for. Week five, two hours, Zone 2, sunglasses on indoors… not glamorous, but it's the slow-cooked kind of progress that the whole thing is built on.
