Diaz Suspension Design

Runt Cartridge Fox 36/Marz Z1, 160 (-'25)/150("26+)

The Diaz Suspension Design Runt Cartridge is a dual-chamber air spring cartridge upgrade for riders who want a more predictable, coil-like feel from a Fox 36 or Marzocchi Z1 Bomber Air without giving up air-spring adjustability. Its patent-pending design targets a near-linear spring curve for improved small-bump compliance and steady mid-stroke support, while a secondary chamber adds tunable end-stroke control for bottom-out resistance.

Where this upgrade stands out on-trail

1. Dual-chamber air spring - Delivers a more linear compression curve for a coil-like ride feel while keeping air-pressure adjustability
2. Tunable progression / bottom-out resistance - Secondary air chamber and valve allow controlled end-stroke support without relying solely on volume spacers
3. Mid-stroke support with small-bump sensitivity - Balances initial suppleness with usable support through the travel for aggressive trail and enduro riding
4. Drop-in installation - Designed as an easy cartridge swap for straightforward service and setup
5. Weight-conscious alternative - Listed as 1/2 lb lighter than coil conversions, and only 20 g heavier than an equivalent amount of tokens/spacers

Compatibility notes - 36 mm version fits 2018+ Fox 36 forks with the NA2 air spring and Marzocchi Z1 Bomber Air forks. Not compatible with NA1 air springs, Z1 Coil forks, or Fox 36 E-Bike forks. Travel listing: 160 mm for forks through 2025; 150 mm for 2026+ forks.