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Ultra-PE fabrics build lighter, stronger, more abrasion resistant bags.

Advanced Polymers

Our Fiber Flight Series are bags built from Ultra-PE fabrics (Ultra High Molecular Weight Polyethylene – UHMWPE). This unique polymer creates ultralight fabrics with unparalleled strength and durability.

10 years of Ultra-PE bags

At Rockgeist, we specialize in working with these unique fabrics. Combined with meticulous design and workmanship, these Ultra fabrics are an essential element in building best-in-class gear.

 Differences Between Our Ultra Fabrics

Dyneema® Composite Fabrics (DCF)

A shiny non-woven composite laminate which is reinforced with Dyneema® fibers mated to a matte polyester backing. 

Core Benefits:

  • Lightest option for sewn bags
  • Dyneema won’t absorb water in rain
  • Unique, flashy patena

Ecopak® Ultra 200/400

A mix of woven Ultra-PE and Polyester, laminated to a polyester film.

Core Benefits:

  • Highest abrasion resistance in its class
  • Exceptional stitch retention and overall durability
  • Available in white, black, grey, navy 

Xpac® Ultra VX-40

Similar to Ecopak’s Ultra series this is a mix of a shiny woven Ultra-PE and Polyester laminated to a polyester film.

Core Benefits:

  • High abrasion resistance
  • Exceptional stitch retention and overall durability

ALUULA Durlyte™

An Ultra-PE film bonded to an Ultra-PE woven core.

Core Benefits:

  • First & only weldable Ultra-PE fabric for 100% waterproof seams.
  • Easy to clean – can’t be stained
  • Won’t absorb water weight in rain
  • High abrasion resistance

FIBER FLIGHT SERIES - Custom Framebags

Custom framebags made with Ultra PE fabrics; the toughest, lightest fabrics available. Maximizes durability while minimizing weight. Awarded Bikepacking.com’s 2018 Gear of the Year top pick.

Custom Lead Time

About 8 weeks for custom bags made to the shape of your bike. Check your place in our queue here. 


Custom-made for a perfect fit using a strategic photo of your bike. View PhotoFit instructions here.

How Ultra-PE Fabric Weight Compares

Made-to-Order Universal Bags are Available in Ultra Fabrics