What type of cables & housing should I buy to replace them on my 2016 M6R Brompton?

I've put a lot of tough miles since I bought my Brompton, and one of my shifting cables finally frayed and fell out of the shifter. It would be wise to go ahead and replace all of my cables and housing for the first time since I bought the bike 2 years ago.

I'm on a bit of a budget. Do I have to buy the replacement cables & housing from an authorized Brompton dealer, or can I just get them from any-old bicycle parts supply?

What diameter cables and housing am I looking for? And what are the minimum lengths of each of the four cables (which I can cut them to match the size of my old cables)?

  • Which shifting type do you have? Apparently your bike is available with a 3-speed internal gear hub, and/or a two speed rear derailleur.
    – Michael
    Oct 14, 2020 at 13:57
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    Though it looks like both versions use normal shift and brake cables with a continuous housing. I.e. 4mm diameter shift cable housing and 5mm diameter brake cable housing. I’d just get 3m housing of each type and the longer cables (except for the front brake).
    – Michael
    Oct 14, 2020 at 14:06
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    Agreeing with Micheal it seems that standard shift and brake cable sizes are used. See this answer for a description of cable and housing construction and dimensions. Note that replacing housing and cable is straightforward but cutting the housing and cable does require a special cutter tool. See this Park Tool Repair article. Oct 14, 2020 at 15:51

1 Answer 1


The Brompton uses standard gear/shifter cables and brake cables. Flat bar brake levers use the same cable head as a mountain bike (i.e. barrel, not pear). The handlebar selection could make a small difference to the actual length you need, but if you are able to remove the existing outer casing and take it to a bike shop (or measure it) you can have the new casing cut to length by the shop, saving you a job and saving wastage.

Gear outer casing is 4mm diameter, the inner wire is 1.2mm or 1.1mm(SRAM). Brake outer casing is 5mm diameter. Good quality stainless steel cables are not expensive, perhaps £2.50 each and the outer casing is generally £2.50/metre.

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