PapaGanoosh

I'm trying to build up a vintage steel bike for the first time and got to installing the rear derailleur. However when I tried installing the gear cable and rear derailleur cable housing (this is for downtube shifters) the cable housing that is closest to the crank will not sit flush against the knob in the frame. You can see this in my photos that the cable housing just pushes straight up rather than running smoothly with the gear cable.

I haven't put the chain on yet, but you'll see that if the rear derailleur were in the same position without the wheel in place, the cable housing isn't sitting flush against the little knob where the housing is supposed to sit. On my other vintage bike they run fairly smoothly. I'm not sure what the issue is here and this is my first time building up a frame so help would be appreciated.

Could it be that the cable housing length is still too long? Is my cable tension not tight enough?

JoeTBM 

I think you are missing something there, I believe is called a "Step Down Housing Ferrule", something like this



That should help keep your housing aligned and have the cable smoothly enter it.

PapaGanoosh

Thank you, didn't know the answer was so simple. That's good to know

Crankycrank

This is a good item to get from a shop. Take the bike in with the cable undone and they can go through their collection to find a good fit.

KerryIrons

And some of them have longer "small section" length to hold the ferrule even straighter. If you buy a Campagnolo cable set, I think they still come with one.

daniell

This is what I use on my bike. It may work on yours.

squirtdad

and for a bit of useless trivia the cable stop on the stay with that shape is sometimes call a divers helmet stop

if you see one it is about 99.99% that you need a stepdown ferrule

sch

A zip tie an inch or so down the chain stay from the cable stop might help as well, but the ferrule, assuming it fits into the
cable stop will keep the cable from the acute angle seen in the pix with the zip tie reducing the bending pressure on the
ferrule from shifting forces. The ferrules pictured may or may not fit into the cable stop hole which looks to be not much
larger than the cable itself.

Iride01 

That's what I did when I put 11 speed Shimano 5800 on my '91 Schwinn Paramount. And they even gave it to me free after hunting for 15 minutes or more.

JoeTBM 

I mailed him 5 different versions that we have "recovered" over the years in our volunteer shop. Hopefully one will fit the bill and the issue will be solved.