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Brompton G Line bottom bracket from Brompton

Brompton G Line bottom bracket from Brompton

Brompton G Line JIS bottom bracket - for the Brompton spider crankset - excluding crank bolts
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£ 40.00 £ 40.00 (Tax included)

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Brompton G Line bottom bracket cartridge - JIS 123 mm

The bottom bracket comes does not come with crank bolts

Note: Not compatible with the older fixed crankset used on 16 inch wheel size Brompton folding bikes or the advanced superlight crankset used on the T Line

This Bottom Bracket is only compatible with the G Line 20 inch wheel size Brompton bike - though not the G Line Electric

The G Line has a 68mm bottom bracket shell the same as a standard Brompton, but with a longer spindle length

Tools Required

For removal / installation bottom brackets, you will need a special tool

Bottom bracket tool for the Thun IBEX JIS bottom bracket - then look here (it's the Park Tool BBT-22) - This is a standard Shimano 22 spline tool

To remove the cranks you will need a crank puller tool - CCP-22 square taper crank puller tool - this tool first screws into the crank then when done up pushes the crank away from the bottom bracket 

To remove the crank bolts you will need a 8mm Allen key / hex wrench

G Line Bottom bracket removal and installation
Removal

Before removing the bottom bracket from your Brompton, you will also need to remove the crank arms (this whole process will be easier if you have a workstand)

Note: The drive side of the bottom bracket undoes reverse to a normal thread - so righty loosey (clockwise)

Note 2: you need to re-use the crank bolts from the old bottom bracket 

Installation

Do not grease the plastic threads on the bottom bracket - the plastic itself will act as a lubricant

Note: The drive side does up lefty righty (in a anti clockwise direction) - not normal tightening - the non-drive side tightens up "normally"

It should be tightened between 24Nm to 30Nm

Crank bolts should be tightened to 30Nm

We made the video below to show how to remove the old bottom bracket from a standard 16 inch wheel size Brompton - the G Line process is exactly the same

Once the cranks are removed, you can remove the bottom bracket itself

This other great article from Park Tool shows how to remove and install the bottom bracket

Brompton 2021 Q part code: Q103998