Brompton chain ring / guard assembly for 54T spider chainwheel

Brompton 54T spider chain ring / guard

This is a replacement Brompton 54 tooth chain ring complete with guard. It is used to replace a worn 54T chain ring or to increase the gearing if you currently have a 44T or 50T chain ring

Chain ring colour: silver
Chain ring guard colour: black

The chain ring is also available in black (this option was originally introduced on black edition models) at a slightly higher price

About the Brompton 54 tooth chain ring and guard 

The Brompton Spider crankset was introduced on new Brompton bicycles at the beginning of 2013 in conjunction with the change to ISO bottom brackets

One of the main benefits of the this crankset over the previous versions is the ability to be able to change the gearing without having to change the complete crank set

Another improvement over previous models is that the chain guard is now held onto the chain ring with screws - previously it was held on with plastic lugs which wasn't as secure, so sometimes the chain guard would fall off

The chain guard is not strictly necessary - but helps to prevent getting your dress / trousers rubbing on the chain / chain ring and getting dirty

Changing the Brompton chain ring and guard

The chain ring - complete with guard - can be changed (it is held on with 5 chain ring bolts - not included - as opposed to being moulded to the crank arm like the previous crankset) to alter your Brompton bicycles gearing. You also need to change the chain accordingly 

It can be used to replace the 44,  50 or 54 teeth chain rings on a spider type crank

This 54 tooth chain ring is the standard on 1 and 2 speed Bromptons from the factory or on a 3 speed with higher gearing from the factory

Changing from the standard 50 tooth 3 speed to 54 tooth will increase your gearing by approx. 10% making getting up hills slightly tougher but giving a higher top speed on the flat

Brompton Q part code: QCHRINGA-SPI-54
Brompton part number: 9020188

Changing the chain ring / guard is fairly simple - so we created this YouTube video to show how it is done. Note: the chain ring in the video is the black edition version, not this silver one

Steps involved in chain ring replacement /installation:

Remove chain (if you are changing from 54-54T, then this is not strictly necessary, but if you are changing the chain ring due to wear we suggest replacing the chain and sprockets) - tools required: chain link tool (not 100% necessary but this will make it easier)

Remove the 5 chainring bolts, 4 of them are two piece and the 5th bolts directly into the back of the crank arm. Keep these safe when removed as you need to re-use them  - tools required: 5mm Allen key (you may also need a CNW-5 chain ring tool if the 4 two part ones just spin as you remove / install them)

Remove the old chain ring (just slide over the pedal crank)

Install the new chain ring - tools required: 5mm Allen key - tighten to 10Nm

Install the new chain - we also recommend changing the sprocket(s) - tools required: chain link tool