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-   -   I need cable routing help (https://www.bikeforums.net/bicycle-mechanics/913291-i-need-cable-routing-help.html)

Andy_K 09-16-13 12:21 PM

I need cable routing help
 
3 Attachment(s)
I've got a 2001 LeMond Nevada City with shift cable stops welded to the head tube, and I can't see a way to route the right shift cable such that it doesn't have conflicts with the front brake cable. (See attached images.)

http://bikeforums.net/attachment.php...hmentid=340870http://bikeforums.net/attachment.php...hmentid=340871http://bikeforums.net/attachment.php...hmentid=340872

It seems like the brake cable has to be routed in front of the shift cable, but when I turn the wheel more than about 35 degrees there's a hard stop until one of the cables pushes the other out of the way. I realize that in actual riding I shouldn't need to turn the wheel that far, but it just seems wrong.

Is there anything I can do about this?

fietsbob 09-16-13 12:33 PM

maybe a cross over of the cables under the DT so arcs more around to the stop than keeping them parallel ..

plus putting the adjuster inline rather than right on the head tube side

maybe a flexible noodle or just the housing run to a ferrule in the place of that adjuster..

But riding , the last situation hard turn like that , is not likely at any normal rate of speed ,

(other than crashing)

Andy_K 09-16-13 01:04 PM

Hmmm.... The adjuster is built in to the cable stop. I hadn't even considered the possibility that it could be removed. I'll take a look at that.

IthaDan 09-16-13 01:09 PM

Cross your cables under the downtube. Some BB guides are stepped to create a vertical (relative to the DT) offset so the cables don't rub. That said, I've done this many times even with the cables touching each other without issue.

Zef 09-16-13 02:21 PM

Just to clarify, in case you don't know, what everyone means by cross the cables under the down tube is to run the shift cables and housing from the brifters around the front of the head tube to the cable stops on the opposite side of the frame from which they start and then allow the bare cables to cross back to their correct/respective sides under the down tube to route properly through the bottom bracket cable guide to the derailleurs.

Since the front brake and its cable/housing turns with the bar/fork, run your cables and housing so that your shift cables are not encumbered by the front brake cables...if that means the shift cable is routed to the inside then so be it....if that means it is routed around the front brake then so be it. This is more a matter of function over form.

I would leave the barrel adjuster in the frame stop unless the caliper arm is hitting it (unlikely). The fit and pressure of just a feruled brake housing may damage the threads in the stop negatively affecting future use.

-j

Crash_N_Carry 09-16-13 02:42 PM

Once you put the brake cable on the calipers will compress. You should get a lot more clearance afterwards.

HillRider 09-16-13 05:32 PM


Originally Posted by Crash_N_Carry (Post 16072221)
Once you put the brake cable on the calipers will compress. You should get a lot more clearance afterwards.

+1 The brake calipers will move out of the way of the shift housing once they are adjusted. Also, it appears your shift housing is longer than it needs to be. Shortening it until you can just turn the bars to their stops will also give more brake clearance.

dsaul 09-16-13 05:47 PM

1 Attachment(s)
I ran into the same problem with the new road frame I built for myself. I used the head tube cable adjusters to avoid the cable rubbing on the head tube, but didn't consider this issue until it presented itself while building the bike the other day. I ended up running the brake cable outside the shifter cables. The brake cable bumps the shifter cable when I turn to the left, but the shifter cable is moving away at the same time and doesn't present a problem. In reality, I probably don't turn far enough for them to hit when I'm riding.

techsensei 09-16-13 05:49 PM


Originally Posted by HillRider (Post 16072804)
+1 The brake calipers will move out of the way of the shift housing once they are adjusted. Also, it appears your shift housing is longer than it needs to be. Shortening it until you can just turn the bars to their stops will also give more brake clearance.

Actually, if you look at his second photo he is compressing the caliper against the rim, clearly showing there is some interference with normal routing. As others have suggested, running the left shifter cable to the right stop and vice-versa may help. Recently I ran into a similar problem where a SRAM Red brake arm fouled the routing no matter what. The only solution seemed to be to not use a SRAM caliper.

Andy_K 09-16-13 06:08 PM


Originally Posted by techsensei (Post 16072878)
Actually, if you look at his second photo he is compressing the caliper against the rim, clearly showing there is some interference with normal routing.

Exactly.

The shift cables are definitely longer than they need to be. My thinking is that it gives the cable more flexibility to flop out of the way. In any event, I'm not sure shortening them will solve the problem because as you can see in the third picture the conflict occurs pretty much right where the shift cable exits the adjuster.

I also don't think crossing the cables will help. The problem is that as I turn the wheel the brake cable, running more or less straight up from the caliper, wants to pass directly directly in front of the shift cable stop.

I did notice that I had the brake barrel adjuster almost fully extended for no particular reason. With that tucked in, the collision doesn't seem to be quite as harsh and with just a little force the brake cable pushes the shift cable out of the way. Maybe that's the best I can hope for?

techsensei 09-16-13 06:21 PM


Originally Posted by Andy_K (Post 16072933)
I also don't think crossing the cables will help. The problem is that as I turn the wheel the brake cable, running more or less straight up from the caliper, wants to pass directly directly in front of the shift cable stop.

In addition to crossing, you might try it with the housing running outboard of the arm.

Andy_K 09-16-13 06:50 PM


Originally Posted by techsensei (Post 16072976)
In addition to crossing, you might try it with the housing running outboard of the arm.

If I understand your suggestion, you are saying that I should run the cable from the left shifter past the brake cable and (slightly) back to the right side cable stop. Is that right?


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