Bicycle Mechanics - STI shift housing overlap preferences?

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masi61
10-11-06, 10:53 AM
When setting up Shimano road brifters what orientation do you prefer for your derailleur housing coming out of the brifters and into the frame stops. Do you like to go a little long and generous and have the front and rear housings overlap, or is it O.K. to cut them a little shorter to where they're just barely touching, or even shorter where they don't intersect at all. I'm thinking of the longer/generous housing cut because the one housing curves around the front brake caliper arch that way. Also, I have shiny silver ferrules in another Shimano housing kit, would these be better than the standard black plastic ones? Thanks again.


Retro Grouch
10-11-06, 11:26 AM
To me a lot depends on the location of the down tube cable stops. If they're low enough I prefer to cross the cable housings to the opposite sides and recross the bare cables under the down tube. That makes for a smoother cable housing arc and less housing rub against the head tube.

Whenever I'm in doubt, I make the cable housings an inch or so little longer. If they're too short you can get "ghost shifting" or inadvertant rear brake application when the wheel is turned too far to one side.

HillRider
10-11-06, 11:39 AM
With downtube (shifter boss) mounted cable stops, I make the housings as short as possible while still allowing the bars to turn fully to their stops both ways. That minimizes the abraision where the cables pass the headtube and reduces wear on both the housing covering and the headtube itself. I usually wind up with the cable loops about 2" apart where they converge in front of the headtube. Again, be SURE you can turn the bars to both extremes without making the cables pull tight.

With cable stops on the headtube, I make the housing as short as will allow full turning of the bars but, since I don't have to worry about them rubbing the headtube, they can be slightly longer than the minimum.

I've heard of RG's technique of crossing the housings to the stop on opposite side of the frame, then crossing the inner wires under the downtube but I've never tried it myself.


masi61
10-11-06, 11:48 AM
The housing stops are head-tube mounted so I'm starting out with them overlapping quite a bit. I went ahead and installed the optical gear indicator, if I don't like it, I'll ditch it later. Crossing cables under the downtube sounds interesting, I guess it could work so long as the line of cable from the housing stops to the bottom bracket cable guide is un-interupted by frame tubing.

SaddleBags
10-11-06, 01:02 PM
One of my bikes was built with overlapping cables. The housings has a beautiful curve but noticed that the cables will click together during rides. It's not a very annoying click and probably not worth my effort in changing. Although, on my next build on another bike, I cut the housing shorter just for that reason.

jimmythefly
10-11-06, 03:33 PM
If you're not positive about stem length, bar height, or handlebar width and reach be sure to leave them a bit long so you can swap around parts easily and not run out of cable.

Rowan
10-11-06, 04:05 PM
The swing of the handlebars between the "stops" (usually just right angles to the top tube is enough) is what determines the most appropriate length. If the housings become taut and pull away from the stops on the head/downtube, they are too short, and may interefere with shifting.

If you are worried about scuffing of the finish around the headtube, get some Velcro soft spots (not the hooked ones) with self-adhesive backing from a newsagency of bigbox store and pop those on where the cable rubs. Works like a charm.

Retro Grouch
10-11-06, 04:48 PM
If you're not positive about stem length, bar height, or handlebar width and reach be sure to leave them a bit long so you can swap around parts easily and not run out of cable.

Excellent point!