Critical Power Test (bike assessment, ~70 min)

What this assessment is

The Critical Power Test is the seeded bike assessment that pairs with the Critical Power calculator to produce your CP (Critical Power, in watts) and W' (anaerobic work capacity above CP, in kJ).

Domain: bike. Estimated duration: ~70-90 minutes. Linked calculator: critical_power.

Important: the calculator wants THREE efforts

The seeded assessment form was originally built around a 2-effort test (3-min + 12-min), but the CP calculator requires three time/power pairs to fit the hyperbolic model. The seeded shape is a starting point; in practice you should run three efforts at distinct durations and feed all three into the calculator.

The shipped calculator recommends ~2-3 min, ~5-7 min, ~12-15 min — the third effort is what stabilises the CP / W' separation.

Recommended 7-step protocol (3-effort)

1. Warm-up (20 min): build Z1 to Z2 with 2 x 30 s spin-ups.
2. 3-min all-out (3 min): maximum effort. Start hard, hold on.
3. Recovery (15 min): easy spin.
4. 5-min all-out (5 min): even pacing — true maximum sustainable effort for the duration.
5. Recovery (15 min): easy spin.
6. 12-min all-out (12 min): even pacing, threshold-style effort.
7. Cool-down (10 min).

Total ~80 minutes. The seeded 5-step shape (warm-up / 3-min / 30-min easy / 12-min / cool-down) still works for record-keeping in the assessment row, but you'll need to run an additional 5-min effort somewhere — either inline (as above) or on a separate session if the full 3-effort isn't feasible in one go.

Inputs the seeded form asks for

The current seeded form has two required fields:

• 3-min Average Power in W.
• 12-min Average Power in W.

If you ran the 3-effort protocol, record the 3-min and 12-min in the seeded form (so the assessment row reads correctly) and also open the calculator directly to plug in the 5-min and get the proper CP/W' fit. A future schema update may expose all three durations on the seeded form.

Outputs

• CP (Critical Power) in watts.
• W' in kJ.

If only 2 of the 3 efforts are run, the seeded assessment still saves a CP estimate using a 2-effort solution, but W' will be less reliable. The 3-effort fit is the recommended path.

How CP and W' feed everything else

• CP anchors the Yousuli bike zones.
• W' lets the Hub project time-to-failure at any power above CP (the supra / VO2 / power tiers depend on W' being set; if W' is missing, those tiers show as "Need W' data").
• Together they drive the bike split projection in race planning wizard step 2.

Common gotchas

• Insufficient recovery between efforts. Each effort needs full or near-full recovery. Cutting short produces a depressed next-effort number and a warped fit.
• Pacing the 3-minute too easy. The 3-minute is the W' anchor. If you pace it like a 5-minute, W' comes back low.
• Pacing the 12-minute uneven. Even pacing produces a cleaner CP. Going out hard and fading skews the fit.
• Skipping the 5-min effort. Two-point fits give you CP and W' algebraically but with no error margin — one mis-paced effort is the whole result. A 3-point fit absorbs honest scatter.

See also

• Critical Power calculator deep dive
• Yousuli bike power zones