Brake Rotors

Brake Rotor Buying Guide

The rotor is the friction surface your pads clamp against. Rotor size directly affects braking power — a larger rotor gives the caliper more leverage and dissipates heat better. Getting the right size, mount type and design affects both performance and safety.

Rotor Sizes

Common MTB rotor sizes: 160mm (XC front, trail rear), 180mm (trail front, enduro rear), 200mm (enduro front, DH rear), 203mm (DH front), and 220mm (DH/e-MTB front for maximum heat capacity). Bigger rotors mean more power and better heat management, but also more weight and slightly more drag. For most trail riders, 180mm front / 160mm rear is the sweet spot. Enduro and DH riders typically run 200mm+ front and 180mm+ rear.

6-Bolt vs Centerlock

Two rotor mounting standards exist. 6-bolt uses six T25 Torx bolts to attach the rotor to the hub — it's the most common standard and used by most hub manufacturers. Centerlock (Shimano's system) uses a splined interface and a single lockring, like a cassette. Centerlock is faster to install and arguably more secure, but limits you to centerlock-compatible hubs. Adapters exist to run 6-bolt rotors on centerlock hubs, but not the other way around.

Floating vs Fixed

Fixed rotors are a single piece of steel — simple, cheap, durable. Floating rotors have an alloy spider (centre) riveted to a steel braking track — this lets the steel track expand when hot without warping, because the rivets allow lateral movement. Floating rotors are better for sustained braking (alpine descents, shuttle runs) where heat buildup causes fixed rotors to warp and rub. For shorter UK trail rides, fixed rotors are perfectly adequate.

Rotor Wear

Rotors wear down like pads — just more slowly. Most rotors have a minimum thickness stamped on them (typically 1.5mm, starting at 1.8-2.0mm). Measure with a vernier caliper at the braking track. A worn rotor reduces pad contact area and braking power, and can eventually crack. Rotors are cheap relative to the consequences of one failing mid-descent.