Brompton chain tensioner assembly for bikes WITHOUT a derailleur

Brompton Standard Chain Tensioner

Chain tensioner for 1 and 3 speed Brompton folding bicycles

Also suitable for 5 speed Brompton folding bikes

This is one of two types of chain tensioners used on Brompton folding bikes

• Standard chain tensioner (no derailleur) - this one
• Derailleur chain tensioner (for Brompton bikes with two rear sprockets)

If you are not sure which one you have - check out our video further down the description

The Brompton chain tensioner is one of the "essential" list of spare parts for Bromptons with a single rear sprochet and performs an important role in keeping the chain taut whether the bike is being ridden or in the folded/parked position

It works using a big spring (internally) to keep the chain under tension

The chain then glides over two jockey wheels - these wheels will wear over time - they are changeable. To make the jockey wheels last longer, keep your chain clean and not over lubricated

This chain tensioner internally geared hubs where only one single rear cog / sprocket is fitted (1-speed, 3-speed or the older 5-speed).

The chain tensioner shouldn't be done up too tight (just over finger tight - approx 5NM for Sturmey Archer and approx 8NM for SRAM hubs). If it is over tightened then you will crack the plastic of the chain tensioner

Instructions for the tensioner are included - or you can see them in the downloads tab

The chain tensioner has to be removed in order to remove the rear wheel - so it is worth knowing how it is done (in case of puncture) even if you don't need a new one

Brompton 2020 Q part code: Q101506
Brompton Q part code: QCTA
Brompton part number: 9023004

We made this short video on the difference between the two chain tensioner types as well as how to remove and install them