Field notes

How Crux works, and why.

The methods behind the numbers, written so you can check them.

Numbers

How many calories does climbing burn?

Most figures are about four times too high. Here is why, what the research measured, and how Crux works out its own number.

29 September 2026 · 8 minute read

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Coming next

Tracking

How the watch knows you are climbing

Height, movement and rest: what the Apple Watch senses on the wall and how Crux turns it into attempts.

Tracking

Just climb: a session with no taps

Why the best logging happens after the session, and how review works.

Beta

How Beta reads a session

What the coach is given, what it is told never to say, and why it shows its evidence.

Beta

What Beta remembers

How a claim made in one session is checked in the next.

Design

Why one app for climbing, training and food

A plan that cannot see yesterday's session is guessing. The case for one logbook.

Training

What the tape means

Colour circuits, grade ranges and why they differ from gym to gym.

Numbers

Training load for climbers

Seven days against twenty-eight, and how to read the result.

Design

Designing Mist

Why Crux has one accent colour, no gradients and one figure per screen.