Home Bike Maintenance Getting the Brompton chain length right!

Getting the Brompton chain length right!

by Petrelli

Brompton originally had only offered 4 different chain’s length, they are 96, 98, 100 and 102 links. Their use are all depended on your chain ring sizes (44T, 50T and 54T) and the sprockets (single or double and various sizes) configurations. So what happened if you require to use a aftermarket’s chainring and/or chain with different sizes configuration? The only way out is to adjust the length of the chain as per the needs.

The wrong chain’s length would greatly reduce the shifting performance, riding efficiency and folding experience on the Brompton. Getting it right is the way to go!

These are bad examples:

Too long – often you will see the lower tensioner wheel being too low

Too long – the tensioner is almost fully opened.

What do you need to adjust the chain’s length:

There are a few tools that you need to adjust the chain’s length, the chain breaker, easy link remover and a temporary chain holder. We will be covering the details of removing and adding links on the other post.

The necessary tools to adjusting the length of the chain.

The chain holder is a handy tool to hold the chain in position while working on the chain’s length.

These are good examples:

After adjusting the length of the chain, your tensioner positions should be looking like the images below. I often use the parallel line method to judge if the length is right.

Just right – the lower tensioner wheel sits “in front” of the upper one.

Just right – it should look like this.

When the Brompton is half folded and the chain length is right. They should form a pair of parallel lines like this.

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