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possible broken cable-head holder inside STI road shifters (pictures)

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possible broken cable-head holder inside STI road shifters (pictures)

Old 08-06-14, 07:40 AM
  #1  
TallRider
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possible broken cable-head holder inside STI road shifters (pictures)

I'm working on a bike with newer 8-speed Sora STI shifters, and I think the bracket piece that holds the cable-head may be broken.

I feed the cable in correctly and it sits where it's supposed to, but the cable head slips out when I wind the shifter to pull cable.

Here are some pictures, with varying degrees of zoom, of the bracket that is supposed to hold the cable head. Does it look to be broken?



EDIT: Here are some pictures with the shifter cable installed.



I insert the cable when the shifter is fully released, and the cable head sits where it is supposed to, against that plastic "wall" and the cable goes through that notch. But sometimes the cable head slides up and over as I move the shift lever to wind the rachet mechanism (so that the chain would move onto larger rear sprockets).

I've seen more coverage (above where the cable head sits) in other STI shifters, so I wondered if some plastic tab broke off, thus allowing the cable head to slide out vertically.

If the cable-head holder part is broken, is there any way to salvage the shifter (which is otherwise quite new and works fine)? Perhaps super-glue the cable head into place, and at least use the shifter until a cable needs to be replaced.
If it is not broken, I may be doing something wrong that the cable keeps slipping out (but I've never had this problem before with STI shifters)
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Last edited by TallRider; 08-06-14 at 09:32 AM.
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Old 08-06-14, 08:01 AM
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e_guevara
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The cable goes in between the notch and the head should stop there. From the pictures, it looks like that the head went behind the notch/stops.

Did you apply tension (pull) on the cable when you test shift (wind) the shifter? Since the cable stop is like a fork, it is the tension from the derailleur spring that holds it against the stop.

Using superglue on the cable head might drip some into the mechanisms inside giving you more trouble.

Edit: Is the shifter full released? Click on the thumb shifter several times to make sure that the gear mechanism has been fully released before inserting the cable.

Last edited by e_guevara; 08-06-14 at 08:06 AM.
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Old 08-06-14, 09:34 AM
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@e_guevara, thanks for your post. I edited the original post to be more clear on the points you raised, and added a couple photos with the cable head installed.
Super-glue might actually do the trick, if I'm able to drip it only onto the area that I want.
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Old 08-06-14, 09:54 AM
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Super glue does not stick well to many plastics because the plasticizers added to prevent brittleness also interfere with glue sticking. It also needs to be deprived of oxygen in order to cure which implies tight-fitting joints which are not the case here. Maybe some JB Weld might be more suitable but I think it is going to be a long shot getting it to work.
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Old 08-06-14, 10:46 AM
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Thanks for the tip on super glue. I will use epoxy. The adhesive actually won't be under substantial stress - when there is tension on the cable, the cable head sits tight against the plastic surface. It's only when there is cable slack that the cable head can pop up, so I think the epoxy should be enough to hold.
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Old 08-06-14, 06:43 PM
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A dab of silicone caulk might work as well and is more easily removed than epoxy.
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Old 08-06-14, 07:50 PM
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Originally Posted by TallRider View Post
Thanks for the tip on super glue. I will use epoxy. The adhesive actually won't be under substantial stress - when there is tension on the cable, the cable head sits tight against the plastic surface. It's only when there is cable slack that the cable head can pop up, so I think the epoxy should be enough to hold.
As I've said before in my previous post, upon installation the RD's return spring puts the cable under tension which seats the cable head onto the holder.

It does seem from the pics that the cable holder in the shifter is pretty scratched up. My old Sora shifters doesn't have this part fully exposed. The cable head goes thru a hole on the side with cable holder behind it, preventing it from slipping out when there is no tension on the cable.

Install the shifter, thread the cable, route it all the way to the RD, and clamp the cable on the mounting bolt. Keep the cable under a slight tension so the head doesn't slip off. Report back on what happens.
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Old 08-07-14, 09:08 AM
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The last two photos show pretty clearly that something has fractured off of the dark grey plastic parts above and to the right of the cable head, likely the pieces which used to form the "pocket" that the head is supposed to nestle into. I think that the shifter unfortunately may be a goner.
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Old 08-10-14, 09:20 PM
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I'd tried the route that e_guevara mentions, keeping the cable under tension. (I think I'd mentioned this in post #5 as well - when there is tension on the cable, the cable head stays where it is supposed to.)
However, the cable head can pop out with any slack in the cable, and I thought it better to get a new cable that's plenty long, and use epoxy to hold the cable head in the broken shifter slot. Everything works fine and hopefully will for a few years.
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Old 08-10-14, 09:29 PM
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Using epoxy or some other glue to secure the cable end into the shifter's spool is not a correct fix in my world. Cables and their ends go through a bit of flex and movement during use. If this movement isn't allowed for (and epoxy/super glue doesn't usually like a bunch of flex) the the "fix" will likely fail.

Have you tried to put this in front of a pro mechanic? If you can bring the bike/shifter to the Franklin Street Clean Machine location they will give you their advice. All Star Bicycles is another good shop to seek help from.

But in the end I suspect you'll be replacing this shifter on your/the rider's dime. Andy.
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Old 08-11-14, 05:30 AM
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the cable cradle is broken
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