Brompton chain tensioner assembly for bikes with a derailleur - QCTADR

Brompton derailleur chain tensioner

Chain tensioner for 2 and 6 speed Brompton folding bikes

This chain tensioner is for Brompton folding bikes with 2 speed, 6 speed SRAM or 6 speed Sturmey Archer / BWR (Brompton Wide Ratio) gears

This can be identified by the fact it has 2 identical looking black jockey wheels where the chain sits in a groove in the jockey wheel

This works as a chain tensioner (keeping the chain tight when riding and folded) and as part of the Brompton designed derailleur mechanism - by having juckey wheels which can move from side to side to allow the chain to move between the two rear sprockets

To make your chain tensioner last as longer - keep your chain clean and not over lubricated

For details of how to adjust the Brompton derailleur, check out this technical video from Brompton.

Fitting instructions are included or can be viewed in the downloads tab

Brompton Q part code: QCTADR
Brompton part number: 9023011 

Weight: approx. 143g

If you have a single, three or five speed Brompton (i.e. no derailleur) then you need the standard chain tensioner (QCTA)

We made this short video to help identify which chain tensioner you have, as well as how to remove and install it

We also made this video about how the chain tensioner fits into the Brompton derailleur system and how to adjust that