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Old 09-29-11, 05:39 PM   #1
tawlly
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Derailleur Cable Criss-Cross question

I'm fitting aero bars and kelly take-offs on an old steel frame, and the fairly stiff compressionless housing for the index shifters I have just won't behave without crossing from left shifter to right cable stop. That's fine. The problem is, I have top-of-bottom-bracket cable guides, so the x-cross under the down-tube isn't going to work.

The shifters seem indexed the same (I counted the clicks), so could I just use the left shifter for the rd and the right for the fd - is this just a question of convention, or is there a detail that's going to get me? The cable stops are the dura ace variety.
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Old 09-29-11, 05:52 PM   #2
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Nokon a segmented metal sleeve, housing would offer
the compression-less requirement
for the klick shifting, stuff, but be much more flexible..
theyre made for STI/Ergo Brifters so a gear cable set , should reach
the cable stop /adjuster on the downtube.

Last edited by fietsbob; 09-29-11 at 05:55 PM.
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Old 09-29-11, 07:09 PM   #3
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Yeah that's a lot more than I'd want to spend to get around this problem, I really don't mind switching the shifting from right to left as long as it doesn't cause a technical problem. Any opinion on that?
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Old 09-29-11, 07:13 PM   #4
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I have Kelly Take-offs mounted on regular drop bars and the "noodles" provided with them let the cables make a smooth curve that easily reaches the downtube cable stop on the same side. If you don't have the noodles I can see why it would be a problem.
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Old 09-29-11, 07:13 PM   #5
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I don't believe that swapping the lever positions is going to work. RD levers have spacing exactly matched to the shift response of a family of RDs. FD levers are spaced for the FD shift, sometimes with small micro clicks on either side for trimming. So even if the total number of clicks happens to be the same, the spacing is different. Of course you could give it a try, not attached but theading a wire, and marking the position the wire at some reference point. If both wires have the spacing pattern, you're in.

If you have to keep to the tighter curve you can try what I did on my bike. Go to a hobby store and buy brass or Stainless tubing that your housing just barely fits through. Cut a sleeve about 4" long, thread up the housing to where it emerges from the tape (under the tape about 1" or so). mark the location, then use a tube bender, or carefully in your hands put a 90 degree medium radius curve into the housing to lead it where you need it to be.

Hint, leave the housing a bit long on both ends so you can experiment with how it works through the entire steering range, when you have it dialed in, trim it and install the gear cable as you normally would. Also be aware that the sharper bend will see more liner wear so if the cable gets stiff over time, be ready to replace the housing.
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Old 09-29-11, 07:20 PM   #6
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Maybe my housing is a little stiffer than usual. I have the noodles, and I can get a smooth curve on the same side but not with enough play for full turning without compromising on bends.
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Old 09-29-11, 07:20 PM   #7
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HillRider's idea sounds like a good one. Could you fit brake noodles from V-brakes to make the sharp bend? They come in 45-, 90- and 135-degree bends so you should find one which works. Some even come with barrel adjusters which would be convenient for getting things dialed in.
Edit: It looks like we posted at the same time. Would a differently-angled noodle help?
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Old 09-29-11, 07:29 PM   #8
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I'm having trouble visualizing your solution FBinNY, it sounds like you might be talking about bends under bar tape, this is all exposed, I've added a link to the kelly product.

http://www.kellybike.com/2nd_xtra_takeoff.html
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Old 09-29-11, 07:32 PM   #9
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The bend I get on the same side is really not a problem except that it doesn't give me enough length to maintain proper range in the steering. If I add more length I get opposing bends in the housing which is a not great right? Most of my knowledge is academic - maestro Sheldon tells me to avoid opposing bends.

Update: after more fiddling I think I've got an acceptable compromise with a same-side run. Thanks for the input.

Last edited by tawlly; 09-29-11 at 08:45 PM. Reason: update
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Old 09-30-11, 07:09 AM   #10
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Why not just install a plastic cable guide under the BB? That's easy enough and then you can run them underneath.
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Old 09-30-11, 09:37 AM   #11
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Why not just install a plastic cable guide under the BB? That's easy enough and then you can run them underneath.
That's a practical answer, and he could probably glue the guide on so he wouldn't need to drill and tap. But there's a hitch. If he has brazed above the BB cable guides, odds are he also has a brazed fulcrum above the chainstay, not below.
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Old 09-30-11, 09:43 AM   #12
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You mean you want to shift your rear derailleur with your left hand ,
and put the right lever on the left side of the bar?

Housing for shifters, typical Shimano low compression, wires standing on end,
is not that stiff,
you can make it more flexible by using a few extra inches of length.
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Old 09-30-11, 09:52 AM   #13
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Not that this would be a solution, but I was just thinking a few nights ago how someone should get thin aluminum tubing or stainless tubing and clear teflon lining inserts (like a noodle) and fuse them in a shallow X-shape half-around double-helix with a downtube clamp or to sit low-profile for the downtube water bottle bolt. This would allow the smooth transition for crossing cables for brifters into opposing downtube stops, then parallel to either side of the waterbottle position, then crossing under downtube and crossing again but staying separate. It'd be superior to anything on the market today. But the cost would probably be prohibitive since only a few bikes would want something like this.
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Old 10-01-11, 02:59 PM   #14
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Quote:
Originally Posted by FBinNY View Post
That's a practical answer, and he could probably glue the guide on so he wouldn't need to drill and tap. But there's a hitch. If he has brazed above the BB cable guides, odds are he also has a brazed fulcrum above the chainstay, not below.
Well, they make clamp-on cable stops for the chainstay that would solve that.
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Old 10-01-11, 03:38 PM   #15
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Well, they make clamp-on cable stops for the chainstay that would solve that.
Yes, my point wasn't that it couldn't be done, but that there was one more factor to be considered along with it's cost. Eventually the crossed routing begins to take a "there was an old lady who swallowed a fly...." kind of scenario.

The simpler answer could be to simply avoid the crossed routing and find a way to improve the bend in the handlebar to frame loop, as the OP apparently has done.
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Last edited by FBinNY; 10-01-11 at 03:42 PM.
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Old 10-01-11, 04:40 PM   #16
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Yes, my point wasn't that it couldn't be done, but that there was one more factor to be considered along with it's cost. Eventually the crossed routing begins to take a "there was an old lady who swallowed a fly...." kind of scenario.

The simpler answer could be to simply avoid the crossed routing and find a way to improve the bend in the handlebar to frame loop, as the OP apparently has done.
Yeah, it does sometimes turn into an 'onion' when you're trying to fix a problem like that.
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Old 10-01-11, 05:53 PM   #17
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You mean you want to shift your rear derailleur with your left hand ,
and put the right lever on the left side of the bar?
Nope, that's not it. What the OP was considering is often done on bikes that have the rd's chainstay cable stop under the stay and downtube mounted housing stops. You install both levers in their normal location but you run the shift cable housing to the opposite side of the frame (left brifter housing to the right side downtube cable stop and vice versa). Then you cross the bare cables under the downtube and run them to the normal derailleur. That keeps the cable housing off of the headtube on tight turrns and avoids rubbing off the paint.

Many modern frames have the housing stops located very high on the downtube or on the headtube itself so the cable rubbing isn't an issue.
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Old 10-01-11, 06:01 PM   #18
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Nope, that's not it. What the OP was considering is often done on bikes that have the rd's chainstay cable stop under the stay and downtube mounted housing stops. You install both levers in their normal location but you run the shift cable housing to the opposite side of the frame
.
It's moot now, but my read of the OP was that he did want to shift the rear with the left and front with the right. Or else why get involved in counting clicks.
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