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Trouble shifting down with the front derailleur.

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Trouble shifting down with the front derailleur.

Old 11-15-13, 12:29 PM
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danielrbaer
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Trouble shifting down with the front derailleur.

Hey,

I'm having trouble shifting to the little ring on my CAAD10. I'm stuck on the big ring now, but when I dry to shift down, it appears as if the front derailleur doesn't move inward far enough to move the chain down. I tried messing with the barrel adjuster, but that didn't seem to help. Prior to a couple weeks ago, this wasn't an issue.

I'm not very experienced mechanically, but would like to figure this out myself if possible. Thoughts?
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Old 11-15-13, 12:38 PM
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Originally Posted by danielrbaer
Hey,

I'm having trouble shifting to the little ring on my CAAD10. I'm stuck on the big ring now, but when I dry to shift down, it appears as if the front derailleur doesn't move inward far enough to move the chain down. I tried messing with the barrel adjuster, but that didn't seem to help. Prior to a couple weeks ago, this wasn't an issue.

I'm not very experienced mechanically, but would like to figure this out myself if possible. Thoughts?
Since this came on new on a bike that never had a problem, I suspect that the FD may have moved. So start by checking that the cage is parallel to the chainrings. Or you can the crank arm as a guide and check for the same cage to arm gap at the back and front.

It's also possible that the inside limit is a bit tight, and was OK with a new chain, but chains get more flexible with age, and now needs more FD motion to shift. You may try backing off the inner limit a half turn and seeing if it makes a difference.

Last is dirt and cable friction. The spring on the FD must overcome both the chain's resistance to shifting and pull cable back to move. dirt or binding on the cable run can be enough that the spring can't overcome both. This is most likely if you notice that it also seems to take more lever force to upshift.

So you have 3 places to look, before getting to the hard stuff.

BTW- Don't forget that you have to help on downshifts by reducing pedal pressure through the shift.
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Old 11-15-13, 12:54 PM
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a77impala
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Are you already on the large gear on the cassette when you try to shift? You may have to shift the front before you reach the large gear on the cassette. The chain may be at to sharp an angle for the front deraileur to exert any force on it.
I have had that happen and shift to the smaller chain ring earlier.
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Old 11-15-13, 01:18 PM
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Originally Posted by FBinNY
Since this came on new on a bike that never had a problem, I suspect that the FD may have moved. So start by checking that the cage is parallel to the chainrings. Or you can the crank arm as a guide and check for the same cage to arm gap at the back and front.

It's also possible that the inside limit is a bit tight, and was OK with a new chain, but chains get more flexible with age, and now needs more FD motion to shift. You may try backing off the inner limit a half turn and seeing if it makes a difference.

Last is dirt and cable friction. The spring on the FD must overcome both the chain's resistance to shifting and pull cable back to move. dirt or binding on the cable run can be enough that the spring can't overcome both. This is most likely if you notice that it also seems to take more lever force to upshift.

So you have 3 places to look, before getting to the hard stuff.

BTW- Don't forget that you have to help on downshifts by reducing pedal pressure through the shift.

Thanks for your detailed response! Turned out I had a fair bit of gunk accumulated in that hard-to-reach spot behind the BB and the cable router. Cleaning it up seemed to do the trick.
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