[CR]Re: brake cable routing

(Example: Framebuilders:Cecil Behringer)

From: <BobHoveyGa@aol.com>
Date: Fri, 28 Jan 2005 16:17:34 EST
To: classicrendezvous@bikelist.org
Subject: [CR]Re: brake cable routing

Marcus writes:
>My question relates to length of brake cale housing.  Most published directions say to have the housing long enough to come straight out of the levers, yet Mario's bike has much shorter cables.  I have seen beautiful vintage bikes with shorter cables, and equally beautiful ones where the cables are very high and loopy.
>What is the optimum length?

When I first started working on bikes I was taught the following guidelines:

1: Cables should be as short as possible... unnecessary length means unnecessary weight, unnecessary friction, and more opportunity for stretch.

2: Cables should be as straight as possible and curves as broad as possible (housing with a large radius bend usually allows the cable to slide more easily than a small radius bend).

3: Any place there's a break (coming out of the levers, going into the derailleur, etc) the housing should enter in a straight line so that the cable is in the center of the housing when it crosses the break... any tilt in the housing will create a point of excess friction. On the other hand, you don't want a few inches of straight cable before the housing starts to curve, that's extra length that's not needed... shoot for a straight line tangent to an arc.

I think those three pretty much cover good mechanical practice, but on top of that I think most of us also have our own aesthetic rules that we follow, consciously or otherwise. Things like making sure that the apex of the curve on both brake housings reach the same height as they arc over the handlebars. Funny how many of these things we do for looks also happen to agree with good mechanical practice... for example, I've noticed that most people find abrupt curves awkward, so even if it were not more efficient for housing to enter a brake lever or derailleur in a straight line, I think lots of folks would do it anyway.

Bob Hovey
Columbus, GA