Welcome to Crack & Rack
A trainer for trad climbers: learn to eyeball which cam fits a crack. A crack is drawn on screen at its true real-world size — your job is to pick the best fitting cam from your rack. This obviously isn't a replacement for real world practice, but might help your intuition for which piece to try first. The quality of an actual placement depends on way more factors than just the size of the crack.
- Calibrate your screen — match a credit card (or ruler) against the screen so cracks are shown at real size on this device.
- Choose your rack — pick the cam set you're learning; the gear and cracks match its real sizes.
- Play — size up each crack and tap the cam that fits. In easy mode the cracks are all in the middle of one cam's size range. In hard mode the cracks can be borderline between two sizes and they're tilted the crack for a tougher read.
- Adventure — try managing your gear, stamina, and fear as you climb a 100 foot route.
Everything is remembered on this device, so you only calibrate once.
Calibrate your screen
So cracks are shown at their true real-world size, tell the game how many pixels equal one millimeter on this screen. Pick a method, match a real object against the screen, then save.
Hold a standard credit/ID card flat against the screen in portrait (tall) orientation and drag the slider until the outline exactly matches the card (54 × 85.6 mm).
Hold a ruler along the line below. Adjust the slider until the line spans the length you set here, then read it off your physical ruler to confirm.
Which cam fits this crack?
Rack: change
Choose your rack
Pick the cam set you're learning. Cracks and gear will match its real sizes; your choice is remembered on this device.
reference
Bars are drawn proportionally so you can see how neighbouring sizes overlap — either size will fit those cracks. Pin cams (📌) to compare them against another set below.