MTB-MAG.COM - Mountain Bike Magazine | [Tech Corner] How To Service BB30 Bottom Bracket Bearings

[Tech Corner] How To Service BB30 Bottom Bracket Bearings

[Tech Corner] How To Service BB30 Bottom Bracket Bearings

28/09/2015
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28/09/2015

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Bottom brackets have almost all changed to the pressfit style on modern mountain bike frames. The BB30 standard is one which uses an oversized axle into some press fit bearing races directly into the frame. There are no screw in elements, thus it is necessary to make sure it is running smoothly about once a month as it is in a very exposed area to water and dirt. This area is very prone to creaks and noise as surfaces can come into contact with the dirt and water easily which works it’s way between metal surfaces and creating the problems. We show you how to check and service a BB30 system.

Tools: Grease, rubber mallet, allen keys, bearing setting tool and a small brush.

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Undo the drive side crank arm by unscrewing it’s centre bolt with a 10mm key.

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Try and pull the left crank free. If it does not move, then switch to a mallet.

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Gently knock the crank out.

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Ease out the last part, you can tap the crank arm with the mallet.

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Almost out!

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Check the cranks for signs of wear and dirt ingress on the crank axle.

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Now check how smooth the bearing is. If it feels ok, then start to clean it. If it feels grinding or rough, replace it.

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First check alignment and re-home the bearing with a plastic bearing setting tool and mallet.

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Take a rag and clean the bearings outer surface.

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Using a fine extraction tool, pull out the rubber seal.

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The exposed bearing race will be visible, make sure no dirt enters at this point.

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With high pressure grease, apply a liberal amount to the exposed bearing race.

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The bearing should be then rotated and amply covered.

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Re-apply the bearing cover seal.

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Now repeat the operation with the bearing on the other side.

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Remove seal, etc and clean, and re-grease. Do not use degreaser.

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Once re-greased, remount the crank axle by sliding it into the bracket area.

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Push it through as far as it will go.

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Check the exposed axle length and mount the required axle spacer o-rings.

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Re-attach the right hand crank at the correct torque.

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Snugg up the axle by rotating the left crank play adjuster.

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Tighten the play adjuster so the axle rotates easily, you are now good to go!

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