2010 Kestrel RT 800 SL with internal cable routing. Just put on a whole Ultegra 6800 group set. When I installed the new brake cables into my frame I hear a scratching/rubbing noise in my top tube. And the lever action is not as smooth as the front brake. I took everything apart and made sure the ends of my brake housings are clean and smooth. I used the same silver ferrules that were on the bike before. when I removed the old cable there was nothing in the frame that broke, fell off, or is rattling around inside. I don't understand what could be different from before.

Help? Please.......

Could be the frictional differences between the original cable and your new one.

Should I try a different cable?

Depends on where you bought it. If you got it from the Bell kits at Walmart they might prove to be less smooth than a higher quality (and cost) from your local bike shop.

Solved problem by getting a new SRAM cable and new housing. But not I was going through the gears and some make more noise than others, and not while cross chaining. I am going to ride the bike for a 100 miles while shifting often to stretch out the cables. Hopefully when j take it back the lbs can fix it. I also wish they would have left more housing for the rear derailleur where it comes out of the chainstay.

It is possible the rubbing came from leaving the wrong amount of slack in the outer cable inside the top tube. The fix may have actually been shortening it so that you now see the back part as being too short. Keep in mind you can slide the cable forward and backward to get it how you like it. Turn your bars all the way to the right and pull the cables through to the rear as far as they can go without the cable binding on the head tube. That is the limit to how much cable you can have at the rear with the current total length. Then decide how you want that length distributed front and rear.

If you want better feedback OP, you need to post some pictures showing both entry and exit of the cable into your frame.

Put some of the rubber donuts on the cable inside the TT. That often helps.

I have a general rule to measure 12" for the length of rear derailleur cable housing. Any less can show up as resrictive and hinder indexed shifting.

That's fine for you, but front end dimensions affect what that number should be: heat tube height, bar width, stem length and angle, spacer stack height, headset height, brifter position on the bars, etc. all matter to what is the right outer cable run length between the brifters and the front cable stops.

Oh that's right.