Brompton seat post bung

Brompton Seat Post Bung Installation Instructions

Current (2017 onwards) model seatpost bung

No tool is required - simply push the bung into the bottom of the seatpost

Pre-2017 model seatpost bung (no longer available)

To secure the rubber bung, tighten the bolt with a 5mm allen key approximately 10 turns. The objective is to achieve a good tight fit without excessive bulging that could interfere with the folding operationTo secure the rubber bung, tighten the bolt with a 5mm allen key approximately 10 turns. The objective is to achieve a good tight fit without excessive bulging that could interfere with the folding operation

The kit used to contain a grey bung for use on aluminium seat pillars - this is (since 2012) no longer available and not included.

The black bung was for use with steel and (no longer available) titanium seat pillars

The easiest way to fit the rubber bung to the seat pillar is to have the bicycle folded, lying on its side, or inverted / upside down

Note: the rubber bung may be a tighter fit in (no longer available) titanium seat pillars and may require twisting to get it in up to the shoulder.

Before fitting the correct rubber bung assembly, check that the cone is just nipped up to the rubber bung but not starting to bulge the rubber. In this condition the rubber bung assembly should slide into the seat pillar up to the shoulder.

This required a 5mm allen key