Bicycle Mechanics - Cable housing length... how much ae you supposed to use?

I re-did my cables and housing (Shimano Ultegra 6600 group) but it got me wondering about how much cable housing is necessary for the bike?

Is there any rule of thumb of how much cable housing length should be used for each section?

The last time I did them the housing from the shifters to the housing stop on the downtube were too short. They didn't bind when shifting but the short housing did not allow me to fully turn the wheel/handlebar really all the way left or right. I also made the housing too short at the RD to the cable stop on the chainstay. Again, it didn't bind or was a problem when shifting. But I could have made it longer.

So this time I made sure I gave a little more length but I think I may have given a bit too much. Again, I don't think it'll be a problem but aesthically it looks a bit off/odd.

Is there a rule of thumb of how much "each section" of cable housing should be for Shimano?

Thanks!

Edit: Dang, I didn't proof read my title! Should be "are" not ae...

Gee3, It'll depend on the bicycle, but I try to get a front appearance like this:
194706

The pros may disagree. ;)

Brad

Same bike, this for the rear, but perhaps just a little more loop (oops).
194708

Brad

How much? Enough to reach. The best length is that gives the gentlest curves, with no reverse curves, and allows full swing of the moving parts.

Most folks do OK with the handlebar to frame section, but it's very common for folks to cut the frame to swing arm loop on suspension too short, causing problems when the suspension is compressed.

Are there any tips on sizing housing beyond holding the uncut housing up to the frame and then trimming to fit?

'I cut it twice and it's still too short.'

It's a 51cm Look frame so the angles on places like the rear triangle leading to the rear brakes is a bit more scrunched for me. So I don't have a nice smooth transition like yours Brad. But your pics give me a good idea. Thanks!!

FB, ok, I think I got it at a good length. It doesn't bind when I turn the handbars and I don't have any sharp curves.

Thanks all for the replies!

Gary

'I cut it twice and it's still too short.'

Doh!! :)

Are there any tips on sizing housing beyond holding the uncut housing up to the frame and then trimming to fit?

'I cut it twice and it's still too short.'

Yes, I eyeball as best I can, and cut it a bit long. Fit and test, then can trim another 1/4-1/2" or so afterward, which is far easier than trying to add back.

Also cut the longest sections first, if you make an error you can salvage the section to cut shorter pieces from.

One at a time, dry fit the full (uncut) housing, using tape on the handlebars as necessary to emulate the cable path. Not an issue with STI's - dry fit into the hood.
Pull the housing to resemble a reasonable "run" to the point of engagement with the frame - typically the barrel adjusters on the DT/HT. hold the housing in place against where it would enter the adjusters (excess housing will hang loose beyond this)

While holding the housing at both ends, turn the handlebars as far as they will go in the direction that will pull the housing. The housing should allow the bars to reach the full extent of the motion (typically to where the HB or lever/hood hits the top tube). There should be very little, if any excess housing between the two points. make a note (mark, hold with thumb, etc) where the housing meets the bottom of the barrel adjuster.
This is where you cut the housing.
Use good quality cutters, clean up the housing (circular profile, no crimps), install your end caps and you are good to go. Repeat on the other side.

For the other lengths, smooth bends are best - no sharp bends. At the rear derailleur the housing will have some "springiness" due to the routing, but keep the bends nice and smooth - a nice loop that comes up and around rather than making a beeline for the derailleur.

If you are replacing old housings and if the old housings are the correct length, then cut the new ones the same length.

Cable and housing kits seem to have a standard length for the short housing at the rear derailleur, 32 cm for Shimano and 33 cm for Campagnolo. For good shifting performance this piece should not be shorter.

Are there any tips on sizing housing beyond holding the uncut housing up to the frame and then trimming to fit?

'I cut it twice and it's still too short.'
Well then, cut it again! A fellow boilermaker or an engineer?

I like them long enough to allow the front wheel to lock to lock. The rear brake loops down after it clears the top tube. The rear der. needs a smooth loop.
Make sure you are using the correct housings.

I installed new levers, cables and housings on my road bike yesterday. As they were, under the bar tape, the brake cables were crimping. I made them longer, and like original ones for the bike. 194800

Helpful tips on cable installation: http://sheldonbrown.com/cables.html

I turn the handlebar all the way to one side then cut the shortest cable housing that will still bottom against the cable stop.