Brompton chain tensioner / derailleur fitting

There are two types chain tensioner for the C Line and earlier Brompton folding bicycle

This video shows the difference, and how to remove and re-install each type (they are pretty similar but not quite)

The video is in 4 parts:

0:15 | Introduction
1:25 | Single / 3 speed chain tensioner
3:55 | 2 / 6 speed derailleur
5:55 | Roadside repair

Introduction - explaining the difference between the two chain tensioners used on Brompton C Line and pre 2022 folding bikes

Chain tensioner for bikes with no derailleur - i.e. single speed and three speed Brompton folding bikes (as well as the older 5 speed) and the B75 / A Line

Chain tensioner for bikes with a derailleur - i.e. two speed (now known as urban) and six speed (now known as explore)

Roadside repair - How to remove the chain tensioner at the roadside (it's all very well showing how it's done in a stand, but you will need to remove it if you get a rear wheel puncture to repair while out riding)