The Tests table

A typical session holds several tests: out and back runs in different positions or with different equipment. The Tests card on the activity page shows all of them on one screen. MyCdA pairs the legs, fits a CdA for each test with the same parameters, and lets you save them all at once. It appears on rides with more than one lap.

How tests are found

MyCdA looks at the laps you recorded with the lap button and pairs each out leg with its back leg. Two laps pair when:

both are fairly straight and at least 300 m long;
they're within 25 % of each other's length;
the second heads back the opposite way (within 30°) and ends close to where the first started;
there are at most 4 laps between them (turnarounds and recoveries).

Short laps in between, such as turnarounds, are left out of the test. Rides without out and back pairs, like circuits or velodrome sessions, list each closed lap (one that ends where it started) as a test instead, skipping laps much shorter than the rest (recovery laps).

Pairing needs GPS. Without it, add the tests yourself.

Correcting the list

Change a test's laps in its Laps field: remove one with its ×, or pick another from the list.
Add test adds an empty row to fill in; the bin removes a test from the list.
Find again goes back to the automatic pairing.
The target button shows a test's laps on the chart and the map, to check it's what you think it is.

Changes to the list aren't stored: next time you open the ride, the tests are found again. What you save is kept (see below).

Shared parameters

Every test of a ride is fitted with the same mass, air density (ρ), Crr, drivetrain loss and air speed source, so their CdAs are directly comparable. They start from the ride settings. The calculator next to ρ looks up the weather where and when the first test starts. Air speed works as on the analysis page (see Air speed); the wind exposure comes from the ride settings.

Changed equipment that changes mass between tests, for example a heavier wheel set? Analyze those tests separately from the analysis page, where each has its own mass.

Reading the table

Time, distance	Of the test legs only, without the turnaround.
Avg. speed, power	Averaged over the time you were moving.
CdA	Fitted so that the test's virtual elevation ends at the same height as it started.
Closure	How far from level the run ends at that CdA. Near zero is normal; a large value means no CdA could close the run, so check the test.

Below the table, the mean, standard deviation (SD) and coefficient of variation (CV) of the CdAs show how consistent the tests are. Repeated tests of one setup typically agree within 2–3 %. See telling real differences from noise.

Each test is fitted by closure alone, with Crr held at the value you entered: one closed run can't separate Crr from CdA. A wrong Crr shifts every test's CdA by a similar amount, so comparisons between tests stay fair, but the absolute values are only as good as your Crr.

Saving and opening tests

Save N tests saves every unsaved test as an analysis named "Test 1 (laps 2 + 5)" and so on, with the table's parameters and its CdA.
Saved tests show a Saved badge and keep their saved values. A test counts as saved when an analysis of exactly its laps exists, however it was created.
Click Test N to open it: a saved test opens its analysis; an unsaved one opens a new analysis that starts with the table's parameters.

Opening a test is worth it before trusting a number: look at its virtual elevation (see Reading the chart), and rename and describe it once saved.

The activity page Analyzing a run

Something missing or unclear? Ask the user community or contact us.