Do I need housing inside the frame?
 

On my new roadbike the brake cable goes through the top tube of the frame. Do I need housing inside the tube or can the wire just run as it is there, and if so, do I need ferrules at the ends before entering the tube?

Depends on how your frame is setup. with some the housing goes thru the frame with others, it's just the cable. Some need ferrules, some don't. I usually just figger it out.

Mmm, a wise answer to a boy that has left the brains at work today :)

If the holes where the cable goes into the frame are big enough for the housing to go right into the frame, then the housing will have to go right through. Do you have cables going through now or are you rebuilding a bike with no rear brake. If the former, tie a string to the cable before you pull it out, so you can pull the new cable through. If the latter you will have to lead the way through with an straightened coat hanger wire, with the string tied to it.

Yep, another stupid design- difficult to set up and adjust, and allows water in the frame. Hope it looks good at least.

No more difficult to adjust than one outside the frame,and if water does get in,a BB drain hole takes care of it.I got several of them. No issues.Just more baloney on a stale moldy bun.

Well, I've worked on a fleet of team bikes with them. Some are better than others. Many can be a real pain to replace the cable, and I'd really rather have a frame that didn't let water in in the first place. Ever see a cross bike with internal cables...?