Campy Shifter Cable Housing length - Frame to RD

[YesNdeed]

Is there a standard length, or algorithm for calculating the shifter cable housing length between the chain-stay contact point and the RD? After a few searches and looking at Campy docs, I'm not finding any pertinent info. A previous build with SR 11, I recall better shifting after replacing cable that looked to be too short a housing length between the frame and RD.

I have a used SR 12 group (big mistake after a recent sale at Merlin), and the cable doesn't reach the RD contact point by about 5mm. Shortening the housing between the frame and RD, or buying a new cable set are options. Housing distance from shifters to frame are at the absolute minimum (not an option for cutting). :help:

[Hindmost]

The short piece of housing in the kit is too short? (It was previously cut?) There is no algorithm as such. I eyeball the housing length so that there is a nice round arc, the cable ends squarely enter the frame and derailleur fittings, and there's not extra cable flopping around. Hard to quantify but easy to visualize.

[YesNdeed]

The short piece of housing in the kit is too short? (It was previously cut?) There is no algorithm as such. I eyeball the housing length so that there is a nice round arc, the cable ends squarely enter the frame and derailleur fittings, and there's not extra cable flopping around. Hard to quantify but easy to visualize.

Too long, if anything. The question is how much of the housing can I cut without screwing things up? Is there an optimal housing length between these two points? At this point I have nothing to lose by experimenting.

[jemoryl]

Don't know about 12 speed, but I've always had better results when leaving that piece just as it comes. Sometimes when I've cut it to look less loopy, the performance wasn't perfect.

[dave thompson]

Too long, if anything. The question is how much of the housing can I cut without screwing things up? Is there an optimal housing length between these two points? At this point I have nothing to lose by experimenting.

The entry angle to the derailleur and to the frame are the important metrics as the correct length can vary from frame to frame.

Hinmost has the best answer.. <snipped>....there is a nice round arc, the cable ends squarely enter the frame and derailleur fittings, and there's not extra cable flopping around...

[ultraman6970]

I was the OP i would try to get another cable and just keep the old in case the FD needs a new cable.

[YesNdeed]

The entry angle to the derailleur and to the frame are the important metrics as the correct length can vary from frame to frame.

Hinmost has the best answer..

Best bet. Worst case, I'll get a new cable set, or supplant what I have with non-Campy housings via LBS. I'm short a brake cable, too. Do yourselves a favor and buy your groupsets new, when you can.

[YesNdeed]

I was the OP i would try to get another cable and just keep the old in case the FD needs a new cable.

Yup. Build and learn.

[cmbicycles]

292mm, or roughly a foot. I recall Salesguy posting that was a recommended length for Shimano housing somewhere on the forum, don't ask me why I remember that and forget so much else. :eek:

I don't actually measure housing, just eyeball a nice loose curve. This is previously used housing and cables from a different size frame I presume? I'd start with a new cable/housing set as you mention the upper housings are at the minimum so probably wouldn't hurt to make them a tad longer as well that way you don't have to rewrap the bars if it is too short. The looser the arcs in housing, the less friction, tighter bends have more friction.

[YesNdeed]

292mm, or roughly a foot. I recall Salesguy posting that was a recommended length for Shimano housing somewhere on the forum, don't ask me why I remember that and forget so much else. :eek:

I don't actually measure housing, just eyeball a nice loose curve. This is previously used housing and cables from a different size frame I presume? I'd start with a new cable/housing set as you mention the upper housings are at the minimum so probably wouldn't hurt to make them a tad longer as well that way you don't have to rewrap the bars if it is too short. The looser the arcs in housing, the less friction, tighter bends have more friction.

Pictured is about 360mm of housing, and looks to be too long. As mentioned, I'm afraid of cutting it too short. Yes, this is previously used (and cut) housing, and the housing between the shifters and frame contact points are longer (420mm or so, and as short as they can be). As for now I'll cut the housing of concern to a lesser length, maybe 292mm or so and accept whatever beating of the cross that comes along with it if I'm wrong ;)

[Dino Suegiù]

Pictured is about 360mm of housing, and looks to be too long. As mentioned, I'm afraid of cutting it too short. Yes, this is previously used (and cut) housing, and the housing between the shifters and frame contact points are longer (420mm or so, and as short as they can be). As for now I'll cut the housing of concern to a lesser length, maybe 292mm or so and accept whatever beating of the cross that comes along with it if I'm wrong ;)

It is a bit difficult to tell from an angled photograph but that definitely looks too long to me.
I think cmbicycles is correct: about 300mm.

If your piece is 360mm, that would make sense with how I eyeball (entry/exit points square as per Hindmost above):
make the piece look like a nice rounded "C" rather than an elongated one. Too short would be half an "O" whereas too long would be an extended "C" with long "legs" (as your piece seems to have).

Mask off your piece at 300mm long before cutting it and then mock it up again on the frame.
You will sense what shape is right, rounded nicely but entering/exiting square, with no excessive square length.

[one60]

I'd make cuts to the left side of the logo to move the logo towards the center of the loop!

[homagesilkhope]

Yep, 12 inches is the standard I've arrived at over the years.

[oldpotatoe]

Pictured is about 360mm of housing, and looks to be too long. As mentioned, I'm afraid of cutting it too short. Yes, this is previously used (and cut) housing, and the housing between the shifters and frame contact points are longer (420mm or so, and as short as they can be). As for now I'll cut the housing of concern to a lesser length, maybe 292mm or so and accept whatever beating of the cross that comes along with it if I'm wrong ;)

Looks a little long as has been mentioned..make sure you use a ferrule at the rear der for the der housing. Just as long as there is a decent sized loop and the der housing enters the rear der straight, not kinking...Cut a wee bit off..it doesn't hurt to be a little too long, just too short. Same for der housing up by the handlebars as they leave the shifters.

[ultraman6970]

Now that i see the picture... i would cut like in the middle between the exit of the hole and the word campagnolo. It should work ok. At the beginning i thought was a steel bike.

What the op can do is just put a generic or a used piece of casing and test 1st. Shimano or jagwire will do just fine.... cut the piece, test and then if happy cut the campagnolo one....

U dont want that casing to be way too long and not too short that the shifting could be affected. Too long is never a problem, the issue is if too short the shifting can get weird.

[teleguy57]

a 2012 post over on WeightWeenies (https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=99531&p=845620&hilit=install+ilinks#p845620) about iLinks and cable length said the magic length ws 292mm. That's what I've run since then and it has always worked for me -- and looks good too.

Right in the middle of the three bears -- not too long, not too short, just right. Caveat is that I've always had bikes with an external rear derailleur housing stop on the CS. If you have something as pictured with internal routing coming out the rear of the dropout YMMV.

[oldpotatoe]

a 2012 post over on WeightWeenies (https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=99531&p=845620&hilit=install+ilinks#p845620) about iLinks and cable length said the magic length ws 292mm. That's what I've run since then and it has always worked for me -- and looks good too.

Right in the middle of the three bears -- not too long, not too short, just right.

Really small potatoes but doesn't that depend on where the housing exits? On the OPs bike, it comes out a hole at back of seat stay..on 'normal', external routing, under the chain stay..I'd say that was was longer. :)

[AngryScientist]

on real road race bikes, there is a minimum radius the housing achieve facing rearward of 65mm.

this is how the officials on motos pull you out of the race if you don't make the time cut during stage races.

https://i5.walmartimages.com/asr/986c7511-a034-400c-b5cf-f315a7735c87_1.10638802cf977f993e4c7e8964c6bc2e.jp eg?odnWidth=612&odnHeight=612&odnBg=ffffff

[Velocipede]

292mm, or roughly a foot. I recall Salesguy posting that was a recommended length for Shimano housing somewhere on the forum, don't ask me why I remember that and forget so much else. :eek:


Pictured is about 360mm of housing, and looks to be too long. As mentioned, I'm afraid of cutting it too short. Yes, this is previously used (and cut) housing, and the housing between the shifters and frame contact points are longer (420mm or so, and as short as they can be). As for now I'll cut the housing of concern to a lesser length, maybe 292mm or so and accept whatever beating of the cross that comes along with it if I'm wrong ;)


Yes, I mentioned 292mm. So, there is a book Shimano puts out for their new components(everyone else does it now too). Well, all components really. It's a huge book with lists of measurements for placement on frames of things like cable stops. The derailleur chapter has the placement of the chainstay cable stop(distance of stop to center of axle) and they list the correct amount of cable housing as 292mm total end to end. So when I cut mine I cut 290mm and then with the ferrules it's 292mm.

I found this out 20+ years ago when I was working on a pros bike and I couldn't for the life of me get the shifting to work perfectly. It was a custom Merlin triathlon bike with bar end shifting. I was trying a couple different lengths that I thought looked right and correct. I ended up calling Merlin and spoke to Rob Vandermark and he listed the housing length. And sure enough it shifted perfectly.

For the OPs picture, with that placement, 292 will be too long since the cable stop is on the seat stay. I will see if I can find the cable length for the seatstays.

NOTE!!! This 292mm measurement, this is for standard derailleurs. NOT the new style that Shimano makes with the B Links. B Link derailleurs require a much shorter piece of housing. The stock housing from Shimano is usually correct. They used to include the correct 292mm piece for the older style. So use the stock piece when possible.

[OtayBW]

on real road race bikes, there is a minimum radius the housing achieve facing rearward of 65mm.

this is how the officials on motos pull you out of the race if you don't make the time cut during stage races.


And I understand that this is the device used for sock height infringement:...;)

[cmbicycles]

Measure vertical distance from where housing leaves frame and enters derailleur, making note of the angle the housing exits the frame and that that section is longer so you will need to make sure to measure in the correct location. That will be your diameter of housing bend, multiply this number by pi (use all digits to assure an accurate calculation) and that is the circumference... then divide circumference by two for half the circumference needed for housing bend. Add the amount of space you want for the bend to sit away from the frame, ex. 2" bottom, 4" top.

Next, critical step, hold the housing so Campagnolo is spaced equidistant from the ends, factoring in the offset of the two housing insertion points. Measure, mark, measure, mark, measure, then when satisfied, sharpen cutters on 16000 grit diamond stone and make one perpendicular cut for upper end. Insert ferrule and housing into place on frame. Be sure to orient "Campagnolo" precisely at this step or all is lost, again, measure measure measure. Bend housing to radius previously calculated and measure proper length of bottom half of housing, making sure "Campagnolo" is spaced appropriately and has maximum visual appeal. Resharpen cutters. Hold housing at proper orientation to assure a proper perpendicular cut when in position, as inside strands will be shorter than outside strands. Stress releive housing bend. Remeasure and make final cut.

If it is too long, you can order a carbon fiber fairing to cover the housing, just make sure it is emblazoned with "Campagnolo", this is where your bicycling sticker collection comes in handy. If you dont have the aformentioned sticker collection, a wtb in the classifieds will rectify the situation. Good luck.

[ScottW]

Correct length of the housing loop should be determined with the rear wheel, cassette, and chain installed. The OP's pic in post #10 shows just frame & derailleur.

Without any tension from the chain, the rear der will sit more rearward than normal. If you were to cut the housing to the visually "correct" length (straight entry at the frame and derailleur ends) in this configuration, then the housing will likely be too short when the chain is installed and putting some forward tension the derailleur.

[YesNdeed]

Measure vertical distance from where housing leaves frame and enters derailleur, making note of the angle the housing exits the frame and that that section is longer so you will need to make sure to measure in the correct location. That will be your diameter of housing bend, multiply this number by pi (use all digits to assure an accurate calculation) and that is the circumference... then divide circumference by two for half the circumference needed for housing bend. Add the amount of space you want for the bend to sit away from the frame, ex. 2" bottom, 4" top.

Next, critical step, hold the housing so Campagnolo is spaced equidistant from the ends, factoring in the offset of the two housing insertion points. Measure, mark, measure, mark, measure, then when satisfied, sharpen cutters on 16000 grit diamond stone and make one perpendicular cut for upper end. Insert ferrule and housing into place on frame. Be sure to orient "Campagnolo" precisely at this step or all is lost, again, measure measure measure. Bend housing to radius previously calculated and measure proper length of bottom half of housing, making sure "Campagnolo" is spaced appropriately and has maximum visual appeal. Resharpen cutters. Hold housing at proper orientation to assure a proper perpendicular cut when in position, as inside strands will be shorter than outside strands. Stress releive housing bend. Remeasure and make final cut.

If it is too long, you can order a carbon fiber fairing to cover the housing, just make sure it is emblazoned with "Campagnolo", this is where your bicycling sticker collection comes in handy. If you dont have the aformentioned sticker collection, a wtb in the classifieds will rectify the situation. Good luck.

It seems essential that this procedure be done in a class 1 cleanroom environment, no? I'll start working on my government clearance in order to gain admission at Los Alamos NL.

Seriously, thanks all for the input. There is now incredible hope for this build!

[teleguy57]

a 2012 post over on WeightWeenies (https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=99531&p=845620&hilit=install+ilinks#p845620) about iLinks and cable length said the magic length ws 292mm. That's what I've run since then and it has always worked for me -- and looks good too.

Right in the middle of the three bears -- not too long, not too short, just right. Caveat is that I've always had bikes with an external rear derailleur housing stop on the CS. If you have something as pictured with internal routing coming out the rear of the dropout YMMV.

Really small potatoes but doesn't that depend on where the housing exits? On the OPs bike, it comes out a hole at back of seat stay..on 'normal', external routing, under the chain stay..I'd say that was was longer. :)

small potatoes? ROFL when that comes from the grand potatoe:)

See my bolded comment, Peter. We're on exactly the same page -- which brings me great relief vs going up against the Campag guru... :beer:

[jemoryl]

Measure vertical distance from where housing leaves frame and enters derailleur, making note of the angle the housing exits the frame and that that section is longer so you will need to make sure to measure in the correct location. That will be your diameter of housing bend, multiply this number by pi (use all digits to assure an accurate calculation) and that is the circumference... then divide circumference by two for half the circumference needed for housing bend. Add the amount of space you want for the bend to sit away from the frame, ex. 2" bottom, 4" top.

Next, critical step, hold the housing so Campagnolo is spaced equidistant from the ends, factoring in the offset of the two housing insertion points. Measure, mark, measure, mark, measure, then when satisfied, sharpen cutters on 16000 grit diamond stone and make one perpendicular cut for upper end. Insert ferrule and housing into place on frame. Be sure to orient "Campagnolo" precisely at this step or all is lost, again, measure measure measure. Bend housing to radius previously calculated and measure proper length of bottom half of housing, making sure "Campagnolo" is spaced appropriately and has maximum visual appeal. Resharpen cutters. Hold housing at proper orientation to assure a proper perpendicular cut when in position, as inside strands will be shorter than outside strands. Stress releive housing bend. Remeasure and make final cut.

If it is too long, you can order a carbon fiber fairing to cover the housing, just make sure it is emblazoned with "Campagnolo", this is where your bicycling sticker collection comes in handy. If you dont have the aformentioned sticker collection, a wtb in the classifieds will rectify the situation. Good luck.

Pardon me, but I think your expertise is needed over in the Silca limited-edition Chain Lube thread!

[Old School]

Correct length of the housing loop should be determined with the rear wheel, cassette, and chain installed. The OP's pic in post #10 shows just frame & derailleur.

Without any tension from the chain, the rear der will sit more rearward than normal. If you were to cut the housing to the visually "correct" length (straight entry at the frame and derailleur ends) in this configuration, then the housing will likely be too short when the chain is installed and putting some forward tension the derailleur.

this^