Internal Cable Routings
 

I just installed the rear brake cable on my new carbon bike with internal cable routings... I set everything up, but then when I went to brake, the cable inside the frame made a scratching sound... is this normal? or is there some trick to get it to stop? or did I just set up the cable wrong?

thanks

what frame?

Its a Boyd B930

http://boydbikes.blogspot.com/2010/1...930-frame.html

http://boydcycling.com/bikes/B930.html

Does the cable require full length housing including the part inside the frame tube or just a bare inner wire? If it is supposed to have the housing run all the way through the frame and you left it out, that could be your problem.

Hillrider raises a good point. Unless the frame has built in fulcrums (cable stops) you were supposed to thread the entire cable with housing.

Another possibility if your frame runs only the bare wire internally is that you somehow crossed one over the other inside the frame, and you're hearing one saw across the other. You can sometimes test for this by varying the tension in one cable while watching the other derailleur for response.

One more possibility is you somehow mis-routed it through or past the BB, and it's sawing at the inside corner within the BB shell.

Lastly, some bikes route the cables crossed in front so the RD wire enters the downtube on the left, and FD wire on the right. They do this to open up the HB to frame curve a bit. With this arrangement, you might hear some scraping where the cables touch as they cross inside the downtube.