The Brutal Engineering Rock Bottom High Pivot Chain Guide is designed for Enduro and DH bike frames that feature an idler pulley on the high pivot that the chain rides on.
The high pivot guide arm is angled to capture the chain at the tangent point of the chainring.
The guide is adjustable radially for 38t chain rings and fewer.
The chain guide features our Slap Guide technology. The harder your chain whips, the more it is pushed back toward the center of the chainring. We engineered the chain path to tight clearances which leaves no room for the chain to disengage from the chainring.
The guide features spacers ranging from 0.25mm to 5mm which allow precise chain line alignment to minimize rubbing.
The chain guide features flexible wings that absorb chain energy to dampen chain motion on rough trails.
The front of the guide is stiff to keep the chain locked dead center on the chainring.
The rear of the guide is bolted to positively capture the chain and restrain vertical chain movement.
Includes all mounting hardware.
Fits on the Rock Bottom frame for high pivot idler bike geometries only.
Designed to work with all standard mountain bike chain sizes.
While the PA12CF25 material is abrasion resistant it will wear over time and require periodic replacement.
The guide is manufactured in Maryland, USA by Brutal Engineering. Material is PA12CF25 formed using Fused Deposition Modeling (FDM) for extreme toughness, high wear resistance, and instant revision updates.
We recommend installing the guide using a bike stand so you can shift through all the gears to get the alignment dialed to minimize rubbing.
Depending on the shape and size of your chainring it may be necessary to remove the cranks from the bike to access the m3 screws which mount the guide arm.
Mount the guide arm using the 3 included M3 countersunk screws. Torque to 0.2nm.
Remove the rear M3 catch bolt and flex the guide fins over the chain. Eyeball the spacing between the guide and guide arm to select a spacer. Insert the M5 mount bolt through the guide and spacer holes.
Move the M5 slot nut and begin threading the screw. As you tighten look at the alignment of the guide and chain. Change spacers as necessary to get the chain as close to centered in the guide as possible.
When the correct spacer is determined, adjust the guide radially so that the ceiling of the guide is just slightly above the chain with no rubbing.
Adjust the rotation of the guide so that the chain does not rub on the chain guide rear catch. The spacer nub will stay in line with the guide mount as you adjust the guide itself. It may be necessary to rotate the entire Rock Bottom frame to get the correct alignment.
Tighten the M5 mount bolt until the guide will no longer move. Do not over tighten as this could stress the guide material.
Install the M3 chain guide catch bolt and tighten until just snug and the gap is closed.
FDM is a form of 3D printing. 3D printed parts will show layer lines and unique cosmetic defects which are to be expected. We test each part for strength and flexibility to ensure there are no layer bonding issues.
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