4mm or 5mm housing?

[compo]

My home brew road bike has downtube friction gear shifters, an Alivio rear mech and a 6 speed freewheel. It works fine with 5mm gear cable housing. I have some indexed levers coming for it so I am wondering if I should change the housing to 4mm. I know on my 8 speed Trek hybrid the indexing is very poor with 5mm but perfect with 4mm so I am wondering if I should buy a foot of 4mm for the road bike.

I know the obvious answer, however my previous hybrid was 6 speed with indexed thumb shifters and that worked fine with 5mm housing so is the size of the housing determined by the number of gears. In reality does a 8 speed cassette require greater shifting precision than a 6 speed freewheel.

 

[jim55]

No it's 4 mm for gear shifters ,no matter how many gears u have

 

[Smokin Joe]

No it's 4 mm for gear shifters ,no matter how many gears u have

On the recommendation of my LBS I'm using 5mm gear cable. They reckon it is better and I have had no issues with it, though to be fair it is neither better or worse..

 

[raleighnut]

Up to 6 speed you are fine with 'universal' brake/gear outers but dedicated gear outer is needed for 'tighter' tolerance shifters. The steel is wrapped in a linear spiral and not 'wound' around like it is on brake cable.