RockShox SID Brain 29", FS-SID-BN-B2 (Specialized Epic)

For sale: a used, really good condition 29er fork.

Original equipment on a Specialized Epic, so it has the "Brain" option.

A rear shock with the same feature is also available as a package deal - 450€.

The "Brain" on a RockShox SID is an innovative, automatic suspension system feature, initially developed by Specialized and RockShox, that adjusts the suspension's firmness based on the terrain. It’s commonly used on XC (cross-country) bikes to balance efficient pedaling on smooth surfaces with the need for responsive suspension on rough terrain.

Here’s how it works:

Terrain Sensing: The Brain uses an inertia valve, located near the rear axle, to detect the type of terrain the bike is riding on. When the bike encounters bumps or rough terrain, the inertia valve opens, allowing the suspension to activate and absorb shocks.

Automatic Adjustments: On smooth, flat ground, the Brain keeps the suspension firm, which reduces pedal bob (the bouncing motion that can happen when you pedal hard) and helps conserve energy. This makes it ideal for climbing or riding on flat surfaces, as it minimizes energy loss.

Customizable Settings: Riders can adjust the Brain Fade setting with a dial, to control how sensitive the system is to terrain changes. Setting it to a "firm" position will make it respond only to bigger impacts, while a "soft" setting will open up the suspension on smaller bumps.

SID Integration: On the RockShox SID, which is a lightweight, performance-oriented XC fork, the Brain provides a noticeable improvement in pedaling efficiency without compromising suspension performance on descents or rough sections of trail. This makes the SID a popular choice for racers and XC riders who need efficiency and responsiveness.

Specifications

Model designator (SF) Brain

Wheel size 29" B

Travel (mm) 100mm

Fork offset 42mm

Maxle included Maxle Stealth

Color (FS) Diffusion Black

Steerer Tapered

Axle 15x110mm BOOST™

Axle to Crown (mm) 511

Brake type (FD) Disc

Crown Material Forged, hollow aluminum

Upper crown type n/a

Lower leg type Magnesium

Upper Tube Finish Fast Black

Upper tube type 32mm straight wall aluminum

Damper adjust Crown

Damping adjustments Extl rebnd, low speed comp to lock

Spring Solo Air

Spring rate n/a

Max Tire Diameter (mm) n/a

Max Tire Width (mm) n/a

Maximum Rotor Size 200mm

Minimum Rotor Size 160mm

https://www.sram.com/en/service/models/fs-sid-bn-b2