# best cable routing method for CX bikes?



## FrancisB (Sep 10, 2006)

Hi,

I'm getting a frame made up for CX, and am wondering if there's a "best" cable routing strategy for CX bikes. 

The 2 options (that I know of) are to route the derailler cables along the top of the top tube, or like a road bike, along the down tube. Is one "better" than the other?

I'm also assuming it's best to offset the top tube cables to the right side of the tube to keep it away from you when you shoulder the bike?

any insight appreciated.

thx,
Francis


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## CDB (Oct 20, 2005)

If on top tube, put them on the top, not the underside, since that might dig into your shoulder. (although Todd Well's 05 national cx championship winning bike had the rear brake cable stops located on the left, underside of the top tube?!) If they are on the top tube, you may have trouble w/ a top pull front derailleur that works w/ the chainrings of your choice. If going the single ring route, not an issue. Or you can get a little u-turn pulley installed below the der. clamp, but above the BB. Then you can use a botom pull der. Most top pull der's don't match up well w/a typical cross chainring gearing combination. Since the rear brake cable needs to be on the top tube, I think you might as well put the others there as well.

I personally don't like the feel of a downtube shift cable against my forearm when shouldering my bike for the run. In fact, I have gotten cuts many times from the cable friction on my forearm. Not recently, but more so when I was starting out as a beginner long ago.

There are two sides of the argument for the rear shift cable. When it goes along the top tube, then down the right seat stay, the cable is exposed to mud dropping onto it from above (think tires flinging it), then moisture running down that cable into the housing that enters the derailleur (disadvantage). Advantage is that the cable loop is less severe of a bend.

When the cable runs downtube style, under the bb, and along the underside of the right chainstay, it is more sheltered from mud (from rear tire) and what does hit it can drop freely to the ground. There isn't as much gravity draining moisture into the housing. But disadvantage is that the cable loop is more severe in this strategy. Not a big deal, really, considering all road bikes are this way. Also, the front wheel will fling mud onto the cable and the grit can accumulate around the bb area creating friction. Nothing that can't be taken care of w/ regular maintenence/lube.

I personally haven't noticed a significant difference in performance between the many cross bikes I've had, whether cables were on top tube or down tube. Either way, if you are racing in the mud a lot, you have to clean, dry, and relube the housing frequently, or just replace it a lot. That makes a bigger difference in my opinion relative to the merits/negatives of either cable run strategy. I also gotten used to having a down tube cable on my arm when shouldering and don't get scraped up anymore. Not a big deal.

A side note, one of my bikes is set up w/ Nokon sealed cable housing. It is in a continuous sealed tube. I am now on my second season w/ the same cable, no maintenence. It is more expensive for sure, so consider that. I got it for free. Since I am only using it for the rear shifting, not a lot is needed. For the same money, you can do a lot of new cable/housing, keeping it fresh every couple weeks as needed.


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## Gripped (Nov 27, 2002)

CDB said:


> <big snip>


CDB did an excellent analysis. I'll add that I race a Merckx that runs the front mech cable via the top tube (pulley for bottom pull mech) and a Redline pit/commuter that runs the front mech cable via the down tube.

I like shouldering the Merckx better however, I've not had any significant personal discomfort shouldering the Redline. If I were getting a bike built, I'd probably go with down tube routing so as to eliminate the need for a top pull mech or a cable pulley.


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## cy1 (Dec 7, 2004)

*Not much to add*

Can't add much to what has already been mentioned.

I think the differences are subtle and either will probably work fine.

My first cross bike had both derailleur cables along the toptube and I found the biggest mud collector was the pulley I used for my bottom pull front derailleur. 

My current bike has the rear along the top tube and the front along the down tube. 

Since I'm in Calif now, it's rather moot as we don't have the same weather as up North or back East


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## atpjunkie (Mar 23, 2002)

*just a matter of preference*

and I don't really buy that TT mounted cables get more exposure to the elements. By the time the tire is throwing down dirt onto the Fr. der. cable it is almost done with a full rotation. DT mounted cables are getting mud and water fresh off the tire. If you don't think some is going to run down the cables you are mislead though there is no housing at the end (as there also isn't on a TT mounted der. fr. cable. ) rear der. cable in a TT mounted system is far more shielded from the elements that DT systems. 
Some people grab bikes by the DT when lifting and they usually don't like a handful of cable, some don't like a handful of cable while gripping the TT before a dsimount. So in reality, the work about the same, DT gives you the ability to avoid the pulley (or use an MTB fr. der) which is a mechanical adavantage though my pulleyed bike shifts really nice. Has a more of a clunk when it shifts, more feel, noisier and not as smooth as Shimano typically is, but very positive.


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## GearDaddy (Apr 1, 2004)

My CX bikes have always run DT style, and that has seemed to work fine.  Haven't replaced cables or housing at for the last couple years. We don't get a ton of muddy courses here in Minnesota.

However, I totally concur with the TT run rear shifter cable getting gummed up more easily in my experiences with MTB riding. My first mountain bike (late 80's model) had DT run shifter cables, and it actually worked OK in the mud. The whole industry switched over to TT run shifter cables, and I've had reoccuring headaches with that last section of cable housing causing stickiness. Water and grit does run right down into that last section of housing after awhile.

I used a beater mountain bike with TT run cables for year round riding and commuting. In order to reduce maintenance I actually drilled out the cable stops on the rear stay and ran a continuous housing all the way to the rear shifter. Of course I had to use the expensive gortex sheathed cables to reduce the friction. It worked great. No maintenance at all for 5 years.

This year I did a couple of MTB races that were complete mudbath slogs, i.e. the kind where your wheels stop turning because they get so caked with mud. I setup my MTB with SRAM drivetrain this year, and it still shifted great even in the worst conditions. It would be cool if you could use SRAM 1:1 actuation for a CX bike. I think it also helps that there is a reduction in the bend of the cable with the way it runs into an SRAM rear der.


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