Cable housing sizes

bing gordon

I'm just installing Dura ace 7900 shifters so I thought I would change the old cable and housings as my older 7801 shifters had the brake housing came out the side of the shifters. I ordered all good quality cables and installed them but I'm not sure if to use the 4mm housing as some tutorials say use 5mm housing for both shifters and brakes,
you thoughts ?

Secteur

Use the smallest you can get away with - just ensure you use break specific outers for the brakes!

Cant see the benefit of using break outers for the gear cables.

I have to say, I thought they came in a standard size and didnt realise you could get varying cable outer sizes?

keef66

Secteur wrote:

Use the smallest you can get away with - just ensure you use break specific outers for the brakes!

Cant see the benefit of using break outers for the gear cables.

I have to say, I thought they came in a standard size and didnt realise you could get varying cable outer sizes?

Generally 4mm for gears and 5mm for brakes, presumably because the latter use a much thicker cable. Also the construction of the outers is different; you could use brake outer for gears, but why would you? It would be heavier and might also not fit into the cable stops / shifters etc properly.
As you say, using gear outer for brakes is a big no no; the brake cable shouldn't fit through it and in any case it wouldn't withstand the forces involved.

ridgerider

I have jagwire 5mm gear specific outers on my bikes. Led to believe the core is fractionally wider in diameter so the inners run more freely.