volosong

Boy, I'm so bummed. I've been taking my sweet time building up a new Pinarello KOBH frame with Ultegra 6800, (since marketed as the Dogma-K). Got most of it put together and took it to my LBS, and had a specific "kid" who I've worked with in the past do the final cable adjustments and have him cut down the steerer tube and double check the torque on all the bolts. Didn't expect it for about a half a week, but he called the next day to have me come and pick it up. Great! Last night, I started wrapping the bars, the final step before the inaugural ride, (I like my tape "just so").

First thing I did was take off his black electrical tape that he applied to hold the cables. That stuff is just messy! Why did he take my white tape off anyway? Cleaned the gunk off and re-taped the cables in extra places so that they would run exactly where I wanted them to run, and I used white tape. A lot cleaner. Finished one side with cloth bar tape, (I'm "traditional"), and was ready to start on the other side when I noticed something that "wasn't quite right".

Hmmm? Huh! Flipped the frame over on it's "back" and I couldn't believe it! He had crossed the derailleur cables under the downtube! Pinarello carbon frames that do not have internal cabling have their adjustment and cable housing stops on either side of the very top part of the downtube. The bare cable runs down either side of the downtube to the plastic cable guide under the bottom bracket. The front derailleur cable goes up through the frame behind the seat tube to the FD and the RD cable continues back to the RD under the chain stay.

The problem with crossing the cables is that they rub against each other and will prematurely wear and fray. And, probably worse is that they rub against the frame and will wear a groove in the carbon! I can sort of understand why he crossed them because the cable make a more graceful bend if the cable coming from the left shifter looped around the head tube and ran down the right side of the seat tube from there and the cable from the right shifter loop around the head tube to the left. But, that's not the way my other two Pinarellos are "wired".

I just hope there is enough cable to re-run them correctly without having to purchase new cables.

The search for a new mechanic starts today. Looks like a highly-regarded Pinarello shop is located in Irvine, about a three hour drive from where I live.

SkyDog75

Crossing cables under the downtube isn't uncommon. Some people prefer it because, as you noticed, it may allow smoother cable bends from the handlebar to downtube. It won't fray your cables. I personally wouldn't do it if crossing caused the cables to rub against the frame, though.

lostarchitect 

Huh, I haven't seen this before. But surely it is not a good idea for the cable to rub against the carbon?

volosong

Thanks for the info that it is something that's done and not unheard of. Still, as it currently is, one of the cables is lightly touching/rubbing against the frame. I don't like that at all.

SkyDog75

You were replying as I made an edit to note that I personally wouldn't do it if the cable contacted the frame. If it's only barely touching, I'd be surprised if it did anything worse than scuff the paint, but I'd prefer to not even do that.

As for crossing the cables in general, I'm sure you can find references on these forums. Or for another arguably more reputable source, you can read about it on Sheldon Brown's site. It's listed on the following page under '"Criss-Cross" Cables':
Cables

FBinNY 

Most of the times I see crossed cables, it's where the fulcums are on the head tube below the line of the downtube, so the wires can cross in space, rather than wrapping themselves along the tube.

With the fulcrums on the sides of the tubes as described, I wouldn't cross the cables because it unnecessarily add friction. Without seeing the specifics I won't fault the mechanic, since things like this are often a matter of balancing pluses and minuses of the options.

Don't worry about the cables wearing where they cross because you won't live that long, and the cables will fail as they do at the head long before they wear at the cross. As for the frame wear, take a look and see how large the contact/friction area is, and if it's just a short spot under the tube, put a piece of teflon tape there.

OTOH, if the cables are actually rubbing on a large area of the tube as they wrap around it, I'd uncross them, both for cosmetic reasons and to reduce friction.

dabac

I've happily crossed cables on top of the down tube, where gravity would help them rub. If that gives cleaner entry/exit, I'm all for it. On the down tube, where gravity is pulling them away, it should be even less of an issue.
Still, it's rarely critical either way, and crossing is breaking the norm. If your mechanic is to be critizised, it's for not telling, and not for crossing.

dsbrantjr

It should be possible to thread thin Teflon "spaghetti" tubing over the wires to keep them from rubbing the frame or each other. The liner from a lined cable housing may also work for this purpose.

shelbyfv

I've run crossed cables on several bikes. Generally it's to prevent the housing from rubbing the head tube. They will not wear where they cross.

JohnDThompson 

Isn't that what those cable "donuts" are for?

volosong

Every donut I've seen are designed to protect the head tube. Never seen them on bare cables half-way down the down tube. What's to keep them from sliding all the way down to the bottom bracket?

update: Called the Pinarello shop in Irvine and the mechanic said that derailleur cables on carbon Pinarellos should not be crossed. Scheduled to take the bike in on Friday and he said I could wait until he re-routes the cables and adjusts the FD/RD trim.

Batavus

Sure he'll say that, he just wants your business. I don't think there's anything wrong with crossing cables. If anything it reduces friction because of the more natural bend near the head tube. 6700 and 7900 bikes could sure use that cable routing because they have built-in increased cable friction. But yours is 6800.

cderalow

... you're obviously going to need new cables, why not do the cabling yourself and have a mechanic adjust them?

It's not rocket science.

bikeman715

There is nothing wrong with cable crossing , it look better and keep the housing from rubbing the headtube .

Dfrost 

The cables have been crossed on my wife's Erickson since Glenn E. assembled that bike in 1997. The cables have never worn where they cross. I've been doing that on my own bikes (where it works) since 2003 with no ill effects and the benefit of smoother cable housing past the head tube, notably with no marring of the HT finish. There's no evidence of higher friction while shifting. I do add a small length of clear tape on the underside of the DT where the cables come closest, but there's no actually rubbing there. OTOH, if the cables normally would be in contact with a frame tube, I wouldn't do it on such a frame.

Reynolds 

No problem with crossing cables. In fact, as others said, it probably reduces friction because the housing curve radius is wider.

xenologer

5/7 of my bikes cross cables
it allows smoother housing curves around the head tube
especially important for us small people with narrow handlebars and controls all tucked in there

fun note, crossing even in places unexpected, like on a mtb toptube routing
or even having rear brake cable cross over (righhand front, lefthand rear)


if you want your LBS to redo it that's fine
but be polite about it,
since he hasn't done anything incorrect, it's just you making a personal preference request
- speaking from perspective of having been the mechanic

SweetLou

Some Specialized bicycles come with the cables crossed out of the box. There is nothing wrong with do this and in my opinion, it is better to cross them.

TireLever-07

I've seen poster #5 's point before. Makes a gentler radius bend. Chris

paulkal

I cross the cables on my bikes, it looks better and the curve of the cables is smoother. So shifting should be better.
Sheldon Brown even has an article about it:Cables

JiveTurkey

It's possible reversing which cable is over/under the other will pull them both away from the tube. This can be tried easily by detaching, re-routing, and re-attaching just one of the cables.

Along with others, I too will cross when it doesn't lead to rubbing on the frame. I wish my road bike allowed it.

Nikola

There's nothing wrong with criss-crossed cables. I do it on every bike whenever it's possible, even on the cheapest bikes. The shifting works much better. As we can read at Sheldon Brown's site Cables

migrantwing

I cross cables at the downtube all the time.

CafeVelo

Giant frames shipped like this till they all got internal routing. I have my bike set up like this as well.

HillRider

Crossing cables was useful when the cable housing stops were mounted to the bosses meant for down tube shifters so the housing tended to rub on the head tube when the bars were turned. With frames having the housing stops on the head tube itself or very close to it, the rubbing problem no longer exists. If the bare cables are indeed rubbing on your frame, I'd certainly recable it unless you can put a protective layer at that spot.