Brompton mudguard roller assembly and screws (for L version)

Brompton rear mudguard roller wheel

The Brompton rear mudguard roller wheel is used as part of the rear mudguard on A Line and C Line bikes with a rear mudguard but no rack (previously known as L type)

1/ The small wheel helps to keep the Brompton stable when in the folded position

2/ The wheel assembly helps to protect the rear mudguard when in the folded position. Without it the weight of the folded bike rests directly in the mudguard, and can cause it to split

3/ When rolling the Brompton (e.g. On a station platform), the wheel helps the rolling (along with the two roller wheels on the rear part of the frame - forming a triangle of wheels)

4/ The back side of the Brompton mudguard wheel is also used for securing the mudguard stays - helping to keep the mudguard fixed to the bike.

Ever wondered what is the screw size that holds the mudguard roller wheel in place? (they have been known to fall out). 
It is M4 x 10mm
If you want to replace the M4 nut on the other side we would recommend a Nyloc one as it's less likely to fall off!

Note: Since 2016 this is (sometimes) available in black using the Brompton Q part code QMGROLA-BK

Brompton Q part code: QMGROLA
Brompton part number: 9017164