The ASTM category (from the American Society for Testing and Materials) tells you what kind of riding a bike component is officially tested and approved for – from smooth roads to full-on downhill abuse.
Why does it matter?
Not every part is built for every trail. The ASTM rating helps you understand how much stress a component can handle – and whether it matches your riding style.
It gives you confidence knowing your gear is made for what you ride.
Category / What it means / Typical use
ASTM 1 / Light riding on paved roads / Urban, commuting
ASTM 2 / Gravel roads, smooth trails / XC, touring
ASTM 3 / Rougher terrain, small drops / Trail, All-Mountain
ASTM 4 / Technical trails, big hits / Enduro
ASTM 5 / Extreme use, jumps, bike park / Freeride, Downhill