The Honest Read
Here's what most amateur cyclists won't believe until they see it: pro cyclists spend roughly 80% of their riding time at a pace so easy that recreational riders could ride alongside them. Maybe even past them on the bike path. That's not me — that's Professor Stephen Seiler's work, replicated across multiple WorldTour teams, talked about at length on the podcast. The reason most amateurs plateau is they ride 50% too hard when they think they're riding easy. Their easy rides aren't easy. Their hard rides aren't hard enough. They're stuck in the grey zone where nothing meaningful adapts.
Zone 2 isn't "easy riding." It's a specific physiological stimulus — mitochondrial biogenesis, capillary density, fat oxidation capacity, the aerobic enzymes that determine how much work you can do before lactate stops you. None of those adaptations come from sweet spot work. They come from time at low intensity. The rider who skips Zone 2 because it feels like they're not training is the rider who can't hold 250W for three hours when it matters.
Where sweet spot earns its place. Sweet spot is a high-stimulus, moderate-fatigue session — useful for time-crunched riders who can't do 90 minutes of Zone 2 mid-week, and useful inside build phases where you want to push the FTP ceiling without wrecking the next two days. Coaches like John Wakefield and Tim Kerrison use sweet spot strategically, not constantly. The mistake amateurs make is treating it as the whole programme. Three sweet spot sessions a week with no Zone 2 base is the fastest way to plateau and burn out simultaneously.
The honest read. If you're picking one to do this season, do Zone 2. It's the foundation. Sweet spot built on no Zone 2 plateaus inside a season; Zone 2 built on its own keeps producing for years. If you have time for both — and any rider with 8+ hours a week does — keep the polarised distribution: roughly 80% of your time in Zone 2, the remaining 20% in genuinely hard work, with sweet spot used inside build phases rather than as the default intensity.
FAQ
Is Zone 2 better than sweet spot?
For most amateurs, yes — but it's a foundation question, not a contest. Zone 2 builds the aerobic base every other adaptation sits on. Sweet spot is a tool you use on top of that base. The riders who skip Zone 2 in favour of three sweet-spot sessions a week are the same riders who plateau by month four and can't hold a long climb when it matters.
What does Stephen Seiler say about this?
Professor Seiler's research — and his interviews on the podcast — make the case clearly: elite endurance athletes spend roughly 80% of their training time at low intensity (Zone 1-2) and the remaining 20% at high intensity. Sweet spot sits in the middle ground, which the polarised model deliberately avoids. Seiler's position is that the middle is where amateurs accumulate fatigue without accumulating adaptation.
How do I know if I'm actually riding Zone 2?
Two practical tests: you can hold a full conversation in complete sentences, and your heart rate stays well below your aerobic threshold (typically 75% of max for trained riders). If your sentences get shorter, or you drift up into the upper end of your zones over the ride, you're probably in tempo or low sweet spot — not Zone 2. Most amateurs ride Zone 2 about 20-30 watts too high.
How much Zone 2 is enough?
Volume-dependent. At 6-8 hours a week, aim for 4-6 hours of Zone 2 with the rest spent on quality intensity. At 10-15 hours a week, push toward 8-12 hours of Zone 2 — you've got the room to build the base properly. The trap is loading sweet spot into your limited weekly hours and skipping the easy work because it doesn't feel productive. Zone 2 doesn't feel productive in the moment. It is.
When does sweet spot become the right tool?
Build phases — 6-12 weeks before an A-race — and time-crunched windows where you genuinely can't fit a 2-hour Zone 2 ride. Sweet spot blocks of 3x15 or 2x20 minutes deliver real FTP stimulus inside an hour. Used strategically inside a polarised year, sweet spot earns its keep. Used as the default intensity for every session, it's the grey-zone trap with a fancier name.