Bicycle Mechanics - Cable housing 4mm vs 5mm?

Is there any advantage to 5mm over 4mm? I am replacing the shifter housing and cables on my road bike and noticed that the shifter housing was 5mm compared to my dirt rig wich has 4mm?

Years ago I had a discussion with the Sram tech support people on this subject. They said that either would work fine but that 5mm housing was a "skosh" better.

Since you asked I went down to check my personal bikes. As I expected, I have a mixture of 4mm and 5mm shift cable housing. It's not something that I notice when I ride so I'd have to say that I have no opinion as to which is better.

5mm is meant for brake housing. I'm sure shifters work fine in either, it's just the opposite that won't work so well (brake cables + 4mm housing)

5mm is meant for brake housing. I'm sure shifters work fine in either, it's just the opposite that won't work so well (brake cables + 4mm housing)

WRONG! While all brake housing does happen to be 5mm, 5mm shift housing, with the windings nearly parallel to the inner wire does indeed exist.

Is a skosh more or less than a tad?

I believe it is less than a tad, but more than a smidgen.

I think I will go with 4mm because #1 I have it, #2 I really like the Jagwire sealed end caps [the ones with the brass insert with the o ring] and can't find them in 5mm. Any other opinions on end caps?

While there might be *some* minor differences from 4 to 5. The only important one is that you should only use the outer cable where you can see lots of strands poking out of the casing ( i.e. NOT spiral ) as gear casing. Brakes should ONLY use spiral wound.

... The only important one is that you should only use the outer cable where you can see lots of strands poking out of the casing ( i.e. NOT spiral ) as gear casing. Brakes should ONLY use spiral wound.

+1

It's not really a question of which is better (not like the shift vs. brake cable difference), but which one fits the bike. Some bikes have brazed-on housing stops that will fit 4mm and not 5mm. The converse isn't all that desirable either, but at least it's possible.

I have a Stumpjumper from 1988.
It uses brake cable that is a full 2mm in diameter.
Where can I find outer cable housing that will fit a 2mm brake cable?

^^Since nobody answered your question, get unlined brake housing, or just get new brake cables that aren't as thick as your pinky. Unlined brake housing tends to have much more friction, and as a result you won't find it in many bike shops. WalMart will have it as part of the "brake cable and housing combo" or whatever they call it now. However, as I previously stated, simply buying new cables is a better option. The diameter of the cable doesn't really matter in this case so long as it has the right end on it.

Is there any advantage to 5mm over 4mm? I am replacing the shifter housing and cables on my road bike and noticed that the shifter housing was 5mm compared to my dirt rig wich has 4mm?

4mm takes 1.1 cables and 5mm takes 1.2. 5mm is supposedly more durable with the 1.2mm cables.

5mm seems to be a bit more tolerant of road dirt and gunk that inevitably ends up inside the housing. More room inside means less friction on the cable, I guess.

4mm takes 1.1 cables and 5mm takes 1.2. 5mm is supposedly more durable with the 1.2mm cables.

This make no sense. Shimano derailler cables are 1.2mm yet every set of Shimano shifters I've bought have come with 4mm housing.

We have found that using the 5mm shift housing for shifting cables has caused some sloppy shifting. Generally this is noticed on long runs, like recumbent and tandem rear derailleurs. when we replaced the 5mm with 4mm the shifting improves! It doesn't make much sense...but that is what we have noticed in the shop. I pretty much use 4mm shift housing all the time now. as to durability of cables as related to diameter, I rarely see broken shift cables, now, I see plenty of rusty cables that don't run in the old housing well. So...for a bike that sees lots of weather I like to us new 4mm linier housing and SS cables, and sealed end caps. I hope that helps.

This make no sense. Shimano derailler cables are 1.2mm yet every set of Shimano shifters I've bought have come with 4mm housing.

That's 100% irrelevant.

That's 100% irrelevant.

How so? You made a blanket statement that "4mm takes 1.1 cables and 5mm takes 1.2." Why is it that Shimano ships 4mm housing with 1.2mm cables then? According to your statement, they should ship 1.1mm cables with the 4mm housing.