Training & Health
Training zones confuse a lot of riders. We explain what zone 2 and threshold work each do, how they feel, and how to balance them through a season.
Every few months I get the same message from a reader: "I ride hard almost every day and I'm not getting any faster." When I ask what "hard" means, the answer is nearly always the same grey, breathless middle ground — too tough to be easy, too easy to be a real workout. That murky zone is where a lot of fitness goes to die, and understanding the difference between zone 2 and threshold is the fastest way out of it.
Training zones are just a way of labelling how hard you're working, usually as a percentage of some anchor number — your heart rate, your power, or in the simplest version, your breathing. Coaches have used all sorts of models over the years (three zones, five, seven), but they're all pointing at the same underlying reality: your body produces energy differently at different intensities, and each intensity trains a different set of adaptations.
The two anchors that matter most for the everyday cyclist are the two ends of the sustainable range:
Almost everything else in your training is defined relative to those two. Get a feel for them and the rest of the numbers stop mattering so much.
You don't need a power meter to do this well. Heart rate works fine, and so does honest self-awareness. The single most useful test I know is the talk test: in true zone 2 you can hold a full conversation in complete sentences, maybe pausing for a breath now and then. At threshold you can manage a few clipped words before you need air. If you can sing, you're going too easy for either. That test has never once lied to me, even on days when my heart rate strap decided to.
Zone 2 is the pace that feels almost insultingly gentle. It's the effort where you finish a two-hour ride thinking you could have gone harder — and that's exactly the point. At this intensity your body is burning a high proportion of fat for fuel and building the slow, structural adaptations that underpin all your fitness: more capillaries feeding the muscles, bigger and more efficient mitochondria, a heart that moves more blood per beat.
None of that is glamorous. None of it shows up on a single ride. But it's the foundation that lets you absorb the hard work later.
The mistake I see constantly — and made myself for years — is riding zone 2 too hard. You feel good, the road tilts up, an ego-bruising rider passes you, and suddenly your "easy" ride is sitting just below threshold. The problem is that this drifts you into that grey middle: hard enough to cost you real recovery, not hard enough to trigger a top-end adaptation. You pay the price twice.
To keep it honest:
The reward is a bigger aerobic engine, which means you go the same speed at a lower cost — and you have more left in the tank when the road actually does get hard.
Threshold sits at the top of what you can sustain. Physiologically it's the intensity around which your body starts producing lactate faster than it can clear it; push much above it and the clock starts ticking loudly. Train right at that line and you nudge it upward, so the pace that used to leave you gasping becomes one you can hold.
This is the work that makes you faster in the ways you feel most directly. A higher threshold means a quicker time up your local climb, a stronger pull on the front of the group, and more comfort holding a hard tempo on a long day.
Threshold efforts are uncomfortable but controlled. It's not the frantic, all-out gasping of a sprint — it's a deep, steady, deliberate suffering that you can just about manage if you stay focused. A classic session looks like:
The honest caveat: the biggest error riders make here is starting too hard. If your first interval is a heroic effort and your third is a survival crawl, you've done the session badly. A good threshold block should feel repeatable — the last interval should look a lot like the first. Aim to finish thinking you could maybe have squeezed out one more, not lying on the verge.
Because these sessions genuinely tax you, one or two a week is plenty for most riders. More than that and you're not recovering enough to adapt.
Here's the part that trips people up: zone 2 and threshold aren't competitors. They're partners, and they train largely different systems. Zone 2 builds the size and efficiency of your aerobic base; threshold sharpens the top of what that base can sustain. Skip the base and your threshold work has nothing to stand on. Skip the threshold and you'll be enormously durable but never particularly quick.
The trap is trying to do both at once, every ride — which lands you right back in the grey zone. The solution is polarisation: make your easy rides properly easy and your hard rides properly hard, and spend very little time in between.
For a rider training around 6 to 8 hours a week, a sane structure might be:
That usually works out to something like 80% of your riding time easy and 20% hard. It looks lopsided on paper. It surprises almost everyone. But that heavy tilt toward easy volume is exactly what lets the hard days be hard — and it's the pattern I keep coming back to after years of trying to be cleverer than it.
Zones aren't a fixed recipe you follow all year. The mix should breathe with your calendar.
The honest reality is that most amateur riders under-do the easy end and over-do the middle all year round. If you fix nothing else, fix that.
"Do I need lab testing to find my zones?" No. A field test — a hard, sustained 20-minute effort on a quiet road or climb, done when you're fresh — gives you a working anchor for both heart rate and power. Re-test every couple of months as you improve.
"My heart rate is all over the place — should I worry?" Heart rate wanders with heat, sleep, caffeine, and stress. On a hot day or a tired one it'll read high for the same effort. That's exactly why I trust the talk test as a cross-check; treat the number as a guide, not gospel.
"Isn't zone 2 just junk miles?" It's the opposite. Junk miles are the aimless grey-zone rides. Deliberate, easy zone 2 volume is some of the most valuable training you'll ever do — it's just quiet about it.
If you strip all of this down, it comes to one uncomfortable instruction: most riders need to ride easy more often and hard less often. Let zone 2 build the engine, let threshold work raise its ceiling, and stop drowning your fitness in the breathless middle. Do that consistently for a few months and you'll get the thing my inbox keeps asking for — you'll actually get faster.
Owen is a former club racer who has ridden more miles than his odometers can remember and coached riders back from plateaus. He writes about road riding and training with a coach's eye and a realist's patience, and believes consistency beats every shiny marginal gain.
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