shifting cable housing- 4mm vs. 5mm?

<< I am using bar end shifters and am thinking of rerouting the housing
so that it runs under the handlebar tape and emerges at the stem. At
present I have the housing flying out from the bottom of the bars.
Using 4mm housing appeals to me to lessen the bump, but I do not know
if there are problems or advantages to it. >>

There's less cable friction inside 5mm housing, but I don't know if it really
makes any difference in performance.

(Mike Krueger) said:

<< I am using bar end shifters and am thinking of rerouting the housing
so that it runs under the handlebar tape and emerges at the stem. At
present I have the housing flying out from the bottom of the bars.
Using 4mm housing appeals to me to lessen the bump, but I do not know
if there are problems or advantages to it. >>

There's less cable friction inside 5mm housing, but I don't know if it really
makes any difference in performance.

Ok, thanks. Why is there less friction in the 5mm housing? Is the
inner diameter of the 4mm housing smaller than on the 5mm housing? If
it is smaller, I'd assume that there would be more contact points on
curves, etc.?

ddandan-<< Is there a significant difference in performance between 4mm cable
housing and 5mm cable housing? >><BR><BR>

In terms of ease of the inner wire sliding thru for great shifting, yes, 5mm is
superior. We get rid of the 4mm stuff at every opportunity. The plastic
ferrules don't help either.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

<< Ok, thanks. Why is there less friction in the 5mm housing? Is the
inner diameter of the 4mm housing smaller than on the 5mm housing? If
it is smaller, I'd assume that there would be more contact points on
curves, etc.? >>

Yes-exactly.
Some people use 4mm because it is a few grams lighter, is already included with
Shimano shifters, and it works OK. 4mm housing usually comes with crappy
plastic end-ferrules, although you can get 4mm metal end-ferrules from
aftermarket suppliers like Bike Nashbar.
I use 5mm housing because a more rigid housing with lower internal friction
seems advantageous, at least in theory, and also because the 5mm metal
end-ferrules fit into the bosses in the STI shifters and adjusting barrels more
snugly with no slop.
Again, I've never measured the difference in performance between 4mm and 5mm
housing, if any, but I'm not concerned with saving 3 grams, either.