cable control Idea.
 

I think bikes that have lots of cables flopping about all over the place are messy. Ive an idea that there should be noodle type cable guides that go into holes in the frame tubes. The guide would stop the outer casing on the outside of the frame tube. Then the bare inner wire would run inside the tube to a guide at the other end of the tube. I originally thought it could just have a 6mm hole for the guide to go through, as thats what bikes with internal cables have. Like the Raleigh 20. But that would be tricky to fish the inner wires out of there. Especialy if there was several cables. So maybe a 10mm hole.

the guides could be used on Handle posts. The outer cables from the controls could be tubular metal as they wouldnt have to be flexible. Then the lower guide would be above the hinge. There would have to be enough flexible outer casing for the handle post hinge and steering to work. I suppose there would only be room on the front part of the main frame tube to run the cables inside the frame.

The guides could be moulded in plastic like gear cable guides that go under BB shells are.

I was going to make a protoype for my city bike. Its got 2 brakes and a gear cable. So would have 3 cables on the handlepost. Then 2 on the frame. The handle post hinge is on the same side as the front brake. But the gears and rear brakes on the other side. I geuss the cables could enter on one side of the tube and exit on another side.

Like any ideas for inventions. I suppose the product is allready on the market. Just not found it yet.

already done since years ..... however a warning. You would need to cut pretty substantial holes into the frame were the frame experiences the most stress. In order to do it right you would need to install cableguiding tubes inside the frame ....thats nasty and expensive work. Having the cables outside makes replacing them easy.
Thor

I thought it had been done before. I did hear about the brittish Lotus carbon fibre bike. They built prototypes for the cable runs inside of the frame.
I didnt think there would be need for huge holes in the frame though. I was thinking on the lines of a front brake hanger that I had on a MTB. It was a moulded plastic sort of plug that went into the flat metal plate that went on the steerer tube.
The cable guide I was thinking of would have the upto 4 cables coming into it. Then there would be a surface on it to suit the tubing shape. And the bit that protrudes into the tube would have slots in it like a BB cable guide. The outer cables are about 5 mm thick. Just depends on the ferrules. Then the inner wires are just over a 1 mm thick. So with the groove seperator being another 1MM, it wouldnt end up all that big a hole.
Ive got a Raleigh RSW and its got full length outer casings on its 3 cables. Gear cable and brake cable go into seperate holes on either side of the single frame tube. A couple of inches back from the headstock. Then they come out the back of the seat tube. The hole there is like 20mm round. There is steel reinforcing plates on the side of the frame tube/ seat tube and bb. I guess since its an old steel frame that doesnt fold, its not under so much stress as a lighter alloy folding bike.