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path for gear housing ? (bike building question)(5 posts)

path for gear housing ? (bike building question)PeterRider
Jul 18, 2002 1:10 PM
I am building a trek 5200 bike. When I put the housing, I directed the rear shifting cable housing to the right and the front shifting cable to the left of the downtube, as it was done on my last trek 5200. But now, when I turn the fork, both housings move, and they make some noise when jumping from rubbing against the trek logo to rubbing against the frame (the housing has a good length though).

I was doing this at my LBS, and the LBS owner told me that I should have done the opposite, with the rear cable on the left and the front cable on the right, and crossing the cables below the downtube. Since the guy is much more competent than I am (very nice dude, and not after the money at all - openroad in pasadena CA), I thought yeah, maybe I did a mistake...

How do you do usually ? I don't really like the crossing-the-cable thing, does it not cause any problem with the cable guide ? (the thing that guides both shifting cables, that you put below the seat tube)... is it really useful ? It is going to take me another hour to do this, so I want to change only if it is useful and it is better to do so.

Building a bike is nice, but it takes much time, especially the first time. I am sure I did all the mistakes that are possible, including inverting the brakes cables, cutting some housing while a cable was inside...

Thanks,

Pierre
cable crossingsDougSloan
Jul 18, 2002 1:20 PM
The idea is that the cables don't bend as sharply around the head tube if they are run "backwards" and then cross under the down tube. This may work on some bikes, but on others the cables may then rub the downtube. I stick to the normal way.

If you are worried about scuffing paint on the head tube, get some clear electrical tape (yup, they make it) and put a piece under the cable on the head tube. Or, just don't worry about it. It's just a bike, and a little scuffing is expected.

Doug
cross them...C-40
Jul 18, 2002 1:34 PM
I started crossing the cables when I built my first C-40. This routing totally eliminates the chance of the cables rubbing on the head tube. Nothing worse than rubbing the paint off a very expensive frame.

As Doug noted, it doesn't work well on all frames, depending on the location of the cable stops. The cables can rub the underside of the downtube. They don't rub on a C-40, but the natural bouncing of the cables (when the bike encounters rough pavement) does allow them to touch the downtube. I place a small piece of clear "bikesaver" tape in this area to keep the cables from marring the downtube.
re: path for gear housing ? (bike building question)brider
Jul 19, 2002 7:58 AM
I can't believe that people are crossing the cables. Why not just trim the housiong? Just make one smooth arc batween the shifter and the cable stop. Voila! No cable housing rub, onle one (large) bend for the cable to make, lighter, and less cable stretch. The housings that come with these systems is soooooo long that it boggles my mind.
Cross dressinggrzy
Jul 19, 2002 8:27 AM
Crossing works pretty well on Cannondales, but not so well on a 5200. the key is where the bosses are located on the down tube. On the C'dales they're under the tube and they don't use the normal adjusters. Other bikes that use the normal adjusters are pretty much forced to put them on the sides of the down tube. Some custom bikes actually place them on the head tube for this reason. In any event if you try the crossed cable thing on a bike with side mounted bosses, as pointed out above, you'll just end up chewing up the paint on your down tube as the cables wrap around the tube on their way to the BB. Even on a C'dale I'll put the little rubber rings on the cables to save the paint. It's much easier on a C'dale MTB. Probably the most satisfacotry solution is to keep the shift cables as short as practical and then use a couple of the little clear self adheasive circle patches that come with the "Sta Tuff" chainstay protector. Pretty nifty really, but any decent heavy duty clear plastic self adheasive material will work. I've also seen people wrap stuff around the shifter housing, but it still wears against the paint. Your primary objective is to protect the paint.