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Shifting trouble that I cant fix by tuning

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Shifting trouble that I cant fix by tuning

Old 11-03-16, 07:54 PM
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mnsam
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Shifting trouble that I cant fix by tuning

Lately I have been having some trouble with shifting that I haven't been able to fix by adjusting the barrel adjuster or cable tension. My rear cassette has been having trouble shifting into the smaller (harder gears). on my bike this would require loosening the cable to adjust into this position. The problem is no matter how loose I make the cable, I cant seem to get it to shift into the smallest couple gears. When I shift all the way into low gear, I can make it shift by pushing the derailer the last fraction of an inch or so, but it won't seem to go into this position on it's own.

Any guesses? I tried lubricating the derailer mechanism and shift cable but no improvement .
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Old 11-03-16, 08:40 PM
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There most likely is still some sort of friction in the cable/housing, as it is only derailleur spring tension pulling on the cable that makes the shift to the smaller cogs. Detach the cable and see if it easily shifts to the small cogs. If so you have just isolated the problem. No, a problem with the derailleur spring is not common.
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Old 11-03-16, 10:32 PM
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There are a few possible causes. As CB said cable friction is a common one. A bent in towards the wheel der. (bent hanger) is another. A very well worn chain (which gets really sloppy side to side) can also cause sluggish shifting. But the fact that you can move the der enough by hand but not by cable suggests cable causes.


This is the time to base line all aspects of your rear portion of your drivetrain. measure chain wear (done as a length over set links but doesn't tell much about side to side slop). Make sure the hanger and age are aligned. Consider replacing the cable and casing, not a bad thing every few years anyway. Check the cog/cassette for looseness. Check your upper pulley for angular slop (should only have side play).


A bike needs some TLC every so often. Sounds like yours does now. Andy
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Old 11-04-16, 05:18 AM
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If you have brifters, check that the shift wire is not starting to fray inside the mechanism; it is much easier to get the wire head out before it breaks than after.
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Old 11-04-16, 07:17 AM
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When is the last time everything has been apart for cleaning and servicing?

Adjusting a worn or dirty system isn't going to do much, if any good. It could just be accumulated dirt, or as others have stated, a warn part or wire.


-Tim-
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Old 11-04-16, 07:38 AM
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I'll echo something Andrew said earlier, but I'll try to stress it more.

I strongly suspect that you have a bent hanger, and if so, you're at high risk of overshifting into the wheel, which can be a very expensive issue.

I doubt that it's a cable problem because that affects all upshifts more or less equally, and tends to respond to trim (cable) adjustments.

So here's what I think is going on.

From time to time shifting would go off, and you'd fix it by adjusting the cable which is fine as far as it goes. But derailleurs don't tend to go out of adjustment without a reason. So, I suspect that you've been progressively bending the hanger inward by degrees, and compensating. Unfortunately, the limits move with the derailleur, and you've reached the point where both inner and outer are of enough to matter. Adjusting only the outer will solve the immediate problem, but the inner is still off. You can adjust both limits and the trim to correct shifting for now, but a bent hanger will prevent optimal shifting, and you'll want to attend to that soon.
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Old 11-04-16, 09:10 AM
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Bike has about 3000 miles since new. Only service I've done on it is cleaning and lubing the chain, cables and other moving parts. All components are still new.

I measure chain wear every 250 miles or so and I'm still between 0.5 and 0.75 so good there.

The cable seems to slide through the sleeve just fine, but not sure how much friction it takes to cause an issue. Either way it's not enough for me to feel with my fingers.

Bent hanger makes a lot of sense. Is this something I can fix myself or does it need to be replaced? Yes, it does only seem to effect up shifts.

It also makes sense since I've been loosening the barrel adjuster 1/8 a turn at a time for a few months to maintain tuning which is the opposite of what I would expect as the cable ages. Was a bit confused about that.
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Old 11-04-16, 09:19 AM
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My bike, early on developed a bent hanger due to being laid down when dismounting on the drive side. After that was straightened out at the bike shop, I've been careful to ALWAYS lay it down on the non-drive side.
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Old 11-04-16, 09:23 AM
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Your LBS has a Hanger alignment tool , Even if you were to buy a new replaceable derailleur hanger,

that will not guarantee it wont need checking for alignment after you install it .. Indexed shifting gets even fussier with More "speeds"

Want to Do Your own work, Buy the tool Too , G'gl found this one, pretty low cost ..

wiggle.com | LifeLine Derailleur Hanger Alignment Tool | Workshop Tools



'/,
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Old 11-04-16, 10:00 AM
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Originally Posted by mnsam View Post

Bent hanger makes a lot of sense. Is this something I can fix myself or does it need to be replaced? Yes, it does only seem to effect up shifts.

It also makes sense since I've been loosening the barrel adjuster 1/8 a turn at a time for a few months to maintain tuning which is the opposite of what I would expect as the cable ages. Was a bit confused about that.
Yes, the best evidence that your hanger is bent is that fact that youve been trimming to move the RD outward on a regular basis.

You can straighten the hanger yourself, either by buying an expensive tool, or doing a passable job with some improvisation. Otherwise this is dealer work that shouldn't be expensive (though it can be). If there's a bike co-op nearby, that's probably your best bet.

Two DIY methods you might use on the hanger (without buying a tool).

1- if you've never adjusted the limits at all, they can be a benchmark you can restore the RD to. Bend the hanger by inserting a 6mm hex key into the mounting bolt and holding both the RD and hex key, bend out and up. Do this by degrees because you don't want to overshoot and bend back and forth. The goal is to bend until both the inner and outer limits are right, though odds are you won't get it perfect, so finish by adjusting both limits.

2- Shift to any gear such that the cage is close to vertical. Stand a yardstick, broom handle, or something similar against the rear wheel as a reference for the vertical plane. You can tie it to the wheel top and bottom so it stay's put. Now stand behind the bike and eyeball the cage, checking that it's parallel, which it is supposed to be. You bend, the same way as before, and finish by making sure your limits are correctly set.

Good luck.
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Old 11-04-16, 08:10 PM
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You guys nailed it. It was both a frayed cable and a bent Rd. Triedn straightening it. Got a lot better but couldn't get it perfect so went to the LBS.


Thanks again!

Originally Posted by FBinNY View Post
I'll echo something Andrew said earlier, but I'll try to stress it more.

I strongly suspect that you have a bent hanger, and if so, you're at high risk of overshifting into the wheel, which can be a very expensive issue.

I doubt that it's a cable problem because that affects all upshifts more or less equally, and tends to respond to trim (cable) adjustments.

So here's what I think is going on.

From time to time shifting would go off, and you'd fix it by adjusting the cable which is fine as far as it goes. But derailleurs don't tend to go out of adjustment without a reason. So, I suspect that you've been progressively bending the hanger inward by degrees, and compensating. Unfortunately, the limits move with the derailleur, and you've reached the point where both inner and outer are of enough to matter. Adjusting only the outer will solve the immediate problem, but the inner is still off. You can adjust both limits and the trim to correct shifting for now, but a bent hanger will prevent optimal shifting, and you'll want to attend to that soon.
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Old 11-05-16, 07:04 AM
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As mentioned several times, make sure the hanger is not bent. Then some times it is necessary to shim the position of the wheel or RD so the limit screws are approx even. Then do the regular RD adjustments.
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