Training Metrics

You don't need to know any of this to use RideTool. The consistency card tells you everything that matters in plain English: your streak, whether you're getting stronger, and whether you're rested or tired.

But if you're curious — or you want to compare notes with a coach or another training platform — here's what each number means and how RideTool calculates it.

TSS — Training Stress Score

What it is: A single number for how hard a ride was. A 1-hour easy spin might be 40 TSS. A 3-hour hard group ride might be 250 TSS.

How it's calculated: RideTool picks the best method available from your data:

1. Power TSS — from normalized power and FTP (most accurate, needs a power meter)
2. Heart rate TSS — estimated from heart rate using the TRIMP formula
3. Duration TSS — estimated from ride time and elevation (always available)

Every ride gets a TSS value regardless of what sensors you have.

Where you see it: Current Status section on the consistency card (this week's TSS vs target).

CTL — Chronic Training Load (Fitness)

What it is: Your long-term fitness level. Think of it as "how much base have I built?" It goes up slowly when you train consistently and drops slowly when you stop.

How it's calculated: A 42-day rolling average of your daily TSS. Consistent riding builds CTL steadily. Sporadic big efforts don't move it much.

What the numbers mean:

• Under 20 — just starting out
• 20–40 — recreational rider
• 40–60 — regular rider with a solid base
• 60–80 — well-trained
• 80+ — competitive fitness

On the consistency card: CTL drives the "fitness" line. If your CTL is trending up over 28 days, you'll see "getting stronger." If it's dropping, "losing fitness."

ATL — Acute Training Load (Fatigue)

What it is: How hard you've been training in the last 7 days. High ATL means you've been pushing it. Low ATL means you've been resting.

How it's calculated: A 7-day rolling average of your daily TSS. It moves fast — a big training week spikes it, a rest week drops it.

On its own, ATL doesn't tell you much. What matters is the balance between ATL and CTL — that's TSB (readiness).

TSB — Training Stress Balance (Readiness)

What it is: Are you rested or tired? TSB is the balance between your fitness (CTL) and your recent fatigue (ATL).

How it's calculated: TSB = CTL - ATL. Simple subtraction.

• Above 15 — race ready (well rested, peak shape)
• 5 to 15 — well rested (good for hard efforts)
• -10 to 5 — balanced (normal training)
• -10 to -20 — tired (carrying fatigue)
• Below -20 — very tired (recovery needed)

On the consistency card: TSB drives the "readiness" line. Positive TSB = "well rested" or "race ready." Negative = "tired" or "very tired."

FTP — Functional Threshold Power

What it is: The maximum power (watts) you can sustain for about an hour. It's the baseline for calculating how hard any ride was relative to YOUR ability.

How it's set: RideTool imports your FTP from Strava or Wahoo if available. If not, it estimates one from your best power efforts. You can also set it manually in Account Settings.

W/kg — Power-to-Weight Ratio

What it is: Your FTP divided by your body weight in kilograms. It's the single best predictor of climbing ability.

How to improve it: Ride consistently. That's it. Your FTP will rise and your weight will stabilize. W/kg follows.

The Bottom Line

All of these numbers are useful for coaches and nerds, but the consistency card tells you what actually matters: are you showing up? If your streak is growing and your dots are filling in, the rest takes care of itself.

Just keep riding.