I am trying to buy new brake cable housing for my road bike, but got confused about the sizes. I was going to go for this one (5 mm diameter). Which should nicely fit around a 1.6 mm brake cable. enter image description here

However, Googling a bit further revealed there are also 3 mm, 4.9 mm or 5.5 mm diameter variations available.

Is there any difference in functionality and performance between these sizes?

Google search hits for reference:

enter image description here

Note: the question is similar to this one (What is the difference between brake cables and derailleur cables?). But there is no information about brake cable housing size in there.

  • Don’t you mean inner and outer diameter?
    – Michael
    Commented Apr 1, 2021 at 14:39
  • 2
    Brake cable housing an shifter cable housing are two different types built for different purposes, of different diameter, outer and inner and in no way interchangeable. There's no universal housing. The question has been answered quite a number of times on this site.
    – Carel
    Commented Apr 1, 2021 at 15:29
  • @Michael: Is the circle with the line through it no the sign for circumference? I see now width is indeed irrelevant.
    – Steven
    Commented Apr 1, 2021 at 17:03
  • @Carel: Can you link me to the answer about the brake cable housing size differences? I do not seem to find it.
    – Steven
    Commented Apr 1, 2021 at 17:04
  • 2
    The two "3mm" products have the same picture; they've probably inherited the error in the diameter from the same place as well
    – Chris H
    Commented Apr 2, 2021 at 8:09

1 Answer 1


5mm is the standard for bike parts made since I don't even know when, 1940s-ish.

6mm was an early MTB thing and is found on some 80s brake parts and frame housing stops. Don't worry about it unless you're working with a vintage mountain bike with overtly chunky housing and cables.

5.5mm is confusing the way a few manufacturers toss the number around. Basically, some special kit-type brake housings use it, typically braided or those with a braided outer, and they also need their own special ferrules, which will come with the housing anyway. There are no frames or parts that need or are designed for 5.5mm.

3mm isn't a thing.

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