Taper and peak: reading your TSB to arrive in form

Two riders show up to the same event. One trained beautifully for months and cracks halfway round — flat, heavy, nothing there. The other did noticeably less in the final fortnight and rides the best day of their year. Same fitness, opposite result. The difference isn't the training block. It's what they did with the two weeks that followed it.

Those two weeks are the peak and the taper, and most self-coached riders get them exactly backwards — either grinding right up to the start line, terrified of losing fitness, or shutting down completely and arriving rested but blunt. Both misunderstand what a taper is for. It isn't a reward or a rest. It's the phase where the fitness you built quietly becomes fitness you can spend. Here's how to read it — and how a deterministic load model actually shapes one.

First: form is not fitness

The whole thing runs on the gap between two numbers. If they're fuzzy, the base, build, peak piece covers them in full — but in one breath:

• Fitness is your CTL — the slow, ~42-day average of your training load. It's everything the base and build phases spent months raising. It barely moves week to week.
• Fatigue is your ATL — the fast, ~7-day average. It spikes with every hard block and clears within days of easing off.
• Form is your TSB — yesterday's CTL minus yesterday's ATL. It's not how fit you are; it's how much of that fitness you can access today. Buried under fatigue, a huge engine is unusable. Fresh, a smaller one delivers everything it has.

Peak and taper are simply the two moves that separate those numbers on purpose. Through base and build you drove CTL up and let TSB sink deep into the negative — you were fit and permanently tired, which is correct. The taper's only job is to let the fatigue fall away faster than the fitness, so form climbs out of the hole and into the positive on the day it counts. Summit models this the way the sport-science does, and never rewrites it with hindsight — your load numbers only ever carry forward, so the form you're looking at is the real running balance, not a retrofitted story.

Performance Management Chart · block + taperIN-APP VIEW

CTL ATL TSB TSS

What a taper actually is: cut volume, keep intensity

Here's the misunderstanding that ruins more races than bad training does: a taper is not two weeks of easy spinning. "Rest up, ride easy, cut it all back" feels right, and it's wrong. Drop your intensity along with your volume and you don't just shed fatigue — you start switching off the very top-end you spent months sharpening. You arrive rested and dull.

The research on this is about as settled as endurance science gets, and it points one way: a good taper slashes volume but holds — sometimes even sharpens — intensity. Fewer hours, same teeth. You keep a small number of short, race-specific quality efforts right through the final week; they cost almost nothing in fatigue but keep the neuromuscular system and the top end awake. What you cut is the volume around them — the long steady hours that built the fitness but whose fatigue you now need gone.

This is where a load model earns its keep, because the intuitive mistake is easy to encode by accident. Summit treats your key sessions as sacred through the taper: as your projected form rises, it does not quietly downgrade a threshold or VO2 session into plain endurance to "protect" the number. That soft taper — the one that keeps the easy volume and sands off the hard edges — is precisely the version the sport-science literature warns accelerates detraining. The volume comes down; the quality stays.

How long, and how it's shaped

The next instinct is to look up a taper length by event: "it's a road race, so one week." Skip that. Taper length isn't set by the label on your event — it's set by how deep the hole you dug actually is. A long, heavy build needs more unloading than a light one to clear the same fatigue, so the taper should scale with your realized training load, not a lookup table. The one firm rule worth stating: genuinely demanding events — multi-day races, stage races, time trials — earn a full two weeks. Everything else is sized to the block behind it.

The shape inside those weeks matters as much as the length. Volume ramps down as the event approaches — roughly two-thirds of your normal load in the first taper week, sliding to under half by race week — and it front-loads: the days closest to the start line are the lightest. You want the biggest drop in fatigue landing in the final few days, not spent early where it goes stale before it counts. Summit weights the taper this way deliberately, decaying the daily load toward the event so freshness peaks on the right morning rather than three days too soon.

The form window: aim for fresh, not flat

So how positive should your TSB be on the day? There's no single magic number, and anyone who hands you an exact figure is guessing at your physiology. What works is a window: Summit steers your form toward roughly +5 to +20 for the event — clearly fresh, but not so unloaded you've started giving fitness back.

That ceiling matters as much as the floor. Keep tapering past the window and the trade flips: you shed fitness faster than you gain freshness, and you arrive with legs that feel wonderful for twenty minutes and hollow after. Under-taper and you're still carrying fatigue you didn't need to. The window is the narrow band where you're rested enough to reach your fitness and not so rested you've bled it away.

And form isn't only a taper output — it runs as a guardrail all season. If your TSB ever falls into a genuinely critical hole mid-block, Summit will force a rest day regardless of what the plan said, because a number that deep means the next hard session won't land anyway. The taper is just the one time you steer form on purpose instead of defending it.

Multi-day events break the simple rules

Everything above assumes a single hard day. A stage race or a multi-day tour like the Gran Diagonal plays by different rules, and the naive taper quietly sabotages it. The thing that fails on day four of a six-day effort isn't your one-day power — it's your ability to go again on legs that are already wrecked. That's durability, and it's the first thing a cut-everything taper sands off.

So Summit tapers multi-day events differently in two ways. First, it sizes the fitness you need off the repeated daily load, not the event total — a six-day race isn't one enormous effort averaged out, it's the same big day, five more times, and the fitness target reflects that. Second, late in the taper it deliberately keeps a pair of back-to-back quality days — two hard efforts on consecutive days — precisely to rehearse chaining hard days on tired legs. A single-day taper doesn't need that; a multi-day one is broken without it.

What it looks like end to end

Here's an illustrative run from the last build week into a two-week taper. Watch the CTL column barely move while the weekly load is cut in half — and the form (TSB) column swing from deep negative to solidly positive across the same fortnight. That swing is the entire point of the exercise.

Illustrative model, not real activity files: CTL, load and form are rounded to show the shape. Your own curve depends on your block depth, your event, and how your body actually responds — which is what the engine computes from your data rather than a generic template.

Weekly load & fitness · 8-week blockBUILD → TAPER

Weekly TSS Recovery week CTL

After the peak: it's a loop, not a finish line

You raced. Now the two worst options are to keep hammering — chasing the fitness you can feel — or to stop dead for a month. Summit does neither. It gives you a short block of active recovery scaled to what you actually did: a longer unload after a six-day tour than after a Sunday crit, because the fatigue you're clearing is real and measured, not assumed. Then it branches on your intent. If your season's genuinely over, you drop into a true transition — easy aerobic riding, zero intervals, fitness allowed to ebb. If it isn't, it holds you at maintenance: enough load to keep your CTL roughly where it is, and one quality session a week to keep the top-end from fading, pointed at nothing in particular until the next goal appears. What it will never do is leave you "peaking" toward a race that doesn't exist — buried under race-specific intensity for no reason. That's the anti-pattern a good coach avoids on instinct, and the one a load model has to be told not to fall into.

The uncomfortable part

The taper is the hardest phase to trust, because it works by doing less at the exact moment your legs come good and every instinct says add a session. That fresh feeling in the final week isn't a sign you're under-training — it is the taper. It's your fatigue draining and your fitness surfacing, on schedule. Pile load back on to chase it and you bury it again three days before it mattered. The same discipline that built the fitness is what lets you spend it: cut the volume, keep the teeth, ride the openers, and arrive. The chart has been pointing at this day the whole time. Let it.