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  1. #1
    Senior Member tmh657's Avatar
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    Trek, chain stay internal cable routing, RD shifting problem

    I have a 1990 Trek 420 with the internal cable routing on the chain stay. Problem is it won't shift down to the smaller cogs. It will get there after a while and will shift OK without the wheel on it.

    I can tell that the cable just isn't moving freely to let the RD go all the way out. I have to pull on it when the wheel is not on to make it go there. I put in a new cable and housing today and did not help.

    Any ideas besides welding a cable guide on the chain stay? Thanks

    I just found this thread, what do you think about the zip tie idea?http://www.bikeforums.net/showthread...tage-chainstay



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    Last edited by tmh657; 03-09-11 at 06:44 PM. Reason: Found thread

  2. #2
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    I think that's one way to solve it. Look at your picture and you'll see that the housing isn't in line with the wire within it. That makes the wire bend as it enters the housing, digging into the corner, and possibly forming a kink there.

    Eons ago I learned to sail on a 35 ton schooner. Hans, the skipper was a fanatic about fair lead of all the lines because it made them run smoother. His constant drilling about fair lead has served me well and translates well to bikes, You want your cables to have the smoothest, runs with minimum curves and no bends.

    Start by holding the housing straight where it leaves the stay and seeing if it helps. If so, you want it to do that on it's own. I don't know your particular bike, but possibly a tighter fitting ferrule, or changing the length of the rear loop will solve the problem.

    The wire tie might be the way to go. On my own bike where I did all the braze-ons myself, each stop is a pair, the stop and a guide set about an inch out to ensure smooth runs (Thank you Hans). You should try to think creatively about how to get the loop to take a good line, for instance pulling it down to the micro-adjust screw with a small piece of line.
    FB
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  3. #3
    Senior Member tmh657's Avatar
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    Quote Originally Posted by FBinNY View Post
    Eons ago I learned to sail on a 35 ton schooner. Hans, the skipper was a fanatic about fair lead of all the lines because it made them run smoother. His constant drilling about fair lead has served me well and translates well to bikes, You want your cables to have the smoothest, runs with minimum curves and no bends.
    Thanks for the insight. Now I want to go sailing on the Chesapeake Bay where I used to live. That sounds like more fun than wrenching right now.

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    Quote Originally Posted by tmh657 View Post
    Thanks for the insight. Now I want to go sailing on the Chesapeake Bay where I used to live. That sounds like more fun than wrenching right now.
    I'll bet it's still pretty cool out on the Chesapeake this time of year.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  5. #5
    Senior Member Bikedued's Avatar
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    I have two of these bikes, and they originally came with spring coiled housing. Aside from finding some of that, your bike shop may have a ferrule that fits the hole correctly, and can hold the housing straight. I haven't found one yet, but I haven't looked really hard either. Luckily, both of my bikes came with the original housing intact. It's the same stuff that Suntour supplied with their bar end friction shifters, and it works perfectly with index shifting, as it does not compress. Also, check that the cable isn't binding in the bottom bracket area, since the cable rides in a groove machined into the BB shell itself. When index cables bind, yhey will shift fine going up. If it doesn't slide easily, it has trouble letting the cable back out. The force of your hand shifting the levers, is stronger than the force of the derailleur spring.,,,,BD

    This stuff right here! Sorry for the ebay link, it was the ONLY picture I could find online?

    http://cgi.ebay.com/Vintage-Nipon-Me...1e657&x=38&y=7
    Last edited by Bikedued; 03-09-11 at 10:20 PM.

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    Certified Bike Brat Burton's Avatar
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    Suspect your problem is the cable housing itself. From the photos it looks like you`re using compressionless housing which is extremely stiff and refuses to take small radius bends.

    It was actually quite common for Shimano SIS systems to use spiral wound cable housing to terminate runs to rear derailleurs for this kind of installation. The other area they were commonly combined with compressionless cables was the short length at the top of the seat tube if a small radius bend was necessary. That will likely solve your issue without the need for tie wraps.

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    Senior Member Bikedued's Avatar
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    The hole on those dropouts will not hold a standard ferrule though? (Shifter or brake)The spring housing I posted early stays straight, and slips right into the opening on the dropout. With the end of the housing just butted against the dropout there 's no way it will stay straight. Not even spiral wound "brake" housing will fit the dropout, as it too is bigger than the opening. There may be one of those special made shifter cable ferrules that has the smaller diameter fitting off the end that may fit snugly, and will hold the housing straight. The stainless spring housing is smaller than brake housng, so it will fit. Bare ended shifter housing might fit, but using shifter housing without a ferrule is just asking for a headache.,,,,BD

  8. #8
    Senior Member Bikedued's Avatar
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    Like this? Spring housing with no ferrule fits perfectly. The only ferrule is on the end at the derailleur.,,,,BD


    http://www.flickr.com/photos/60000045@N08/5513777819/

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    Certified Bike Brat Burton's Avatar
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    Quote Originally Posted by Bikedued View Post
    Like this? Spring housing with no ferrule fits perfectly. The only ferrule is on the end at the derailleur.,,,,BD


    http://www.flickr.com/photos/60000045@N08/5513777819/
    LOL If thats your bike you`re the one that should have all the answers! If a spiral wound housing has been flat filed then the only purpose a ferrule usually serves is to keep the plastic sheathing from fraying. If this installation doesn`t need a ferrule and the SIS is working perfectly then I`d be good with it.

  10. #10
    Senior Member Bikedued's Avatar
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    It's what came on the bike. Granted it is odd to see such a thing on a bike ten years after most companies stopped using it, but it works. this stuff is the size of SIS shifter housing, lasts forever unless horribly kinked, and can be oiled from the outside to provide slick shifting. Spiral brake housing even filed flat, and the vinyl covering removed, will not fit iinto the collar on the dropout. It's an odd size no doubt. I guess the collar on the drop could be drilled to accept a ferrule, but I have no earthly idea if the material is thick enough.,,,,BD

    Yep that's my bike. I snagged it for $70 + tax at a pawn shop. A 1985 600 model. I will take some proper pictures of it soon. It was converted to 7 speed early 90's Shimano 105, with mid 90's RSX STI's. My 86 520 has the same housing at the RD.
    Last edited by Bikedued; 03-10-11 at 08:33 AM.

  11. #11
    Senior Member tmh657's Avatar
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    I did put some new compressionless housing on there thinking it would help but obviously it doesn't and it's too long. I might have some of that spring housing laying around and will try that or some plain shorter housing.

    I look at how my cable exits the stay and it's a "DOH" moment. What was I thinking? Thanks for all the input.

  12. #12
    Senior Member tmh657's Avatar
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    I found some of that spring housing and cut it to length. It works pretty good but still won't drop onto the smallest cog right away. Just have to live with it.

  13. #13
    Senior Member Bikedued's Avatar
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    No problem at all. Glad to help out a fellow vintage Trek owner!

    Ahh... I see you found some!! It may be only a turn or two on the limit screw that is slowing the chain down. Look from the back of the bike after it finally drops, and see how far over the derailleur is past
    the small cog towards the dropout. If it is a little to the next biggest cog, loosen the limit screw until it's even with the small cog. A delayed shift on the top or bottom end is almost always a limit screw issue, or in rare cases on forged drops a slightly bent hanger. Judging by the condition of the drops, probably the limit screw. It could also be an accushift issue, but that derailleur looks like one made after they ironed out the problems.,,,,BD
    Last edited by Bikedued; 03-10-11 at 06:39 PM.

  14. #14
    Certified Bike Brat Burton's Avatar
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    The cable run definately looks a lot better. Your cable is a little different from mine but in any case it might just be fine tuning as suggested.

    I've posted a few pictures just as a reference. These are on a 1988 model SIS with downtube shifters and the 10.5 length section of this cable housing is the only housing on the entire shifting system.

    DSC01809a 600 x 800.JPGDSC01804b 1000 x 400.JPG

  15. #15
    Senior Member Bikedued's Avatar
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    Okay enough dropout pics. Here's mine all cleaned up and "nearly" just how I want it. Going to change the cogs to a new 7 speed corncob 12/23, install a new chain, and lose the reflector bracket on the Stronglight Headset. Who at Trek thought that was a good idea, lol?,,,,BD


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