The material Rapha has chosen for these pants is excellent. It is both stretchy and breathable and it does a nice job of repelling moisture.
Rapha Trail Gore-Tex Pants
Rapha's Trail Lightweight pants are a cut above the rest - MBR
7 of the Best New Mountain Bike Pants Ridden & Rated - Pinkbike
Rapha Trail Knee Pad review – super comfortable knee protection
Men's Trail Lightweight Pants
Rapha Releases First Collection of Performance Trailwear for Autumn / Winter - Mountain Bike Press Release - Vital MTB
Rapha Trail Pants review - MBR
H&M Releases Cycling Collection and We Tested It
First Impressions: Rapha Trail Fast + Light Shorts and Lightweight Tank - Bikerumor