# I need help with brake and shifter cable



## robertdingson (Oct 29, 2011)

Hi i just got a dura ace 7900 group set and tried to install it with jagwire cables but it didnt work well. The shifting wasn't smooth as well as the braking. I know shimano recomends their PTFE coated cables but does anybody know a better cable for 7900. BTW i also tried the shimano SIS cable with the same results. I need your inputs ASAP pls. thanks.


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## PJ352 (Dec 5, 2007)

robertdingson said:


> Hi i just got a dura ace 7900 group set and tried to install it with jagwire cables but it didnt work well. The shifting wasn't smooth as well as the braking. I know shimano recomends their PTFE coated cables but does anybody know a better cable for 7900. BTW i also tried the shimano SIS cable with the same results. I need your inputs ASAP pls. thanks.


Honestly, there isn't enough information here to provide you with any reliable feedback. Even when specified, shifting issues can be caused by a number of things, ranging from poor housing cuts/ finishing to sticky ferrules to too short a RD housing (to name just a few).

Very generally speaking, poor shifting is commonly caused by resistance along the cable path, so (IME) the best way to narrow that cause is to test each cable section running from the shifter to the derailleur, ensuring that it runs freely, but that's just a start in the diagnosis/ repair.

If possible, provide some additional details...


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## ziscwg (Apr 19, 2010)

Jagwire makes the cables for Shimano. I can't see it being the actual cable. 

New housing too?

A kink somewhere in the cable? Even a seemingly insignificant one in the wrong spot can cause issues.


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## weltyed (Feb 6, 2004)

check where the cables exit the brifters. many times it can develop drag there. and make sure you do this before wrapping the bars.

if you are experiencing this issue with both shifters and brakes, i would think its more user error than the cables of levers. try it a few more times. if that doesnt work, have a friend who is handy with a wrench take a look or wheel it down to the lbs. aske them to fix it. then, when paying, ask what they had to do. you may get pointers. most wrenches dont mind sharing that information.


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## Camilo (Jun 23, 2007)

The problem isn't the cables. You need to install any cable system properly which includes proper routing, proper housing lengths/loops (not too short/tight and not too long) and proper cutting and dressing of the housing ends.

Of all of this (length, routing, cuts), the only one that I've seen that actually noticably degrades performance is improper cutting and dressing of the housing ends. Actually, skimping on the housing length/loop at the rear derailleur is also a common source of problems. Many people make it too short and the loop too tight.

Read any of a million online guides, as well as your derailleur's tech documents for proper routing and housing length, expecially at the rear derailleur. 

Sheldon Brown has some good info on this, but there's lots out there. 

Jagwire are fine cables and perform excellently.


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## robertdingson (Oct 29, 2011)

The Shimano SIS seemed to work a little better especially with the shifter cable but the brake cable definitely has some issues. The cables itself are brand new and i tracked it from lever to brakeset no issues. do you think i should go with thier PTFE coated brakesets? BTW what are you using on yours?


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## robertdingson (Oct 29, 2011)

BTW i have the FSA K wing handlebar so pretty much the routing or bends of the cable depends upon the handlebar shape.


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## TWB8s (Sep 18, 2003)

does the frame have internal or external cable routing?


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## PJ352 (Dec 5, 2007)

robertdingson said:


> The Shimano SIS seemed to work a little better especially with the shifter cable but the brake cable definitely has some issues. The cables itself are brand new and i tracked it from lever to brakeset no issues. do you think i should go with thier PTFE coated brakesets? BTW what are you using on yours?


According to Shimano's tech docs, the 7900 shifters require PTFE cables for both derailleur and brake cables. Housing is specified as SP41 for derailleurs and SLR for brakes. 

FWIW, there have been a couple of threads here on RBR where members have experienced niggling shifting issues. The addition of the Shimano cables/ housings seemed to help minimize the added resistance sometimes encountered with under bar tape/ internal cable routing. As always, YMMV.

Here's the tech doc I was referring to:
http://techdocs.shimano.com/media/t...04/SI-6RT0A-004-ENG_v1_m56577569830702962.pdf


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## robertdingson (Oct 29, 2011)

Internal for the brakes only i have a Trek Madone 5.2 Pro


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## AndrwSwitch (May 28, 2009)

I usually just buy bulk housing. IME, the most important parts of getting good shifting and braking are routing the cables without any kinks, being anal about the ends of the housings, and clean parts. (No crap in your shifters, no crap in your derailleurs, no crap on the little bushings in your brakes.) A good, positive connection between the housing and the shifter is important and can be a little more difficult with housings that are routed under the handlebars. So it's worth paying attention to how, exactly, you route that portion of the housing. If the housing's not routed as well as it could be on the bars before you tape, you can pull it away from the shifter. It's stiff enough to mess up shifting, but not stiff enough not to.

Who's cutting the ends of your housings? I have a little milling tool that makes it a lot easier to get square ends, which I find to make a big difference. You can also do it with a hand file, bench file, grinding wheel on a drill, and I'm sure some other things I'm not thinking of. The only thing that's not okay is just cutting the housing and sticking a ferrule on it. You need to open the inner liner, but I find that to be more of an installation issue - you probably wouldn't have been able to run the cables at all if you didn't get those open one way or another.


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## PJ352 (Dec 5, 2007)

robertdingson said:


> Internal for the brakes only i have a Trek Madone 5.2 Pro


If you're running Shimano 7900 shifters, you have under bar tape brake _and_ shifter housing, thus the cable/ housing recommendations I noted earlier. Those recommendations _only_ apply to 105, Ultegra and DA groups having hidden derailleur housing because of the potential for increased cable/ housing resistance.


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