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Installed new cables - can't engage all gears now

2K views 11 replies 6 participants last post by  2cflyr 
#1 ·
I changed out the cables on my bike and shifting is not quite the same now. I can't get the small cog to engage whether I am using the 50 or 34 chainring. To install the cable, I had the largest chainring and smallest cog engaged and pulled the cable until taut and tightened the cable in place.

Also, when I shift to the large cog in the back, there is some rubbing between the chain and the spokes. I have adjusted cable tension and the cable seems loose enough when try to shift from the 13 to the 12 cog but still it won't move over to the 12. If I adjust more to loosen the cable, it won't shift the smaller to larger cogs.

I don't want to mess with the limit screws - it worked before the cables were changed so that isn't the solution. Any ideas as to what is wrong?

Thanks in advance!
 
#2 · (Edited)
OK a few things are wrong, some were always wrong but you didn't notice, and the other might be you.

First of all, you might have put too much tension on the cable when you set it up. If there's room to tighten (shorten) the threaded trim adjuster use that to slacken the cable, until everything is OK. My favorite place to set the trim is on the 2nd smallest sprocket, adjusting cable length until shifting between it and high is smooth and crisp in both directions.

If you can't get this to work it brings up the second and more serious issue, which is the limit screw settings.

Your inner limit is definitely wrong since you can overshift into the spokes. Shift into high gear, or as close as possible, then shift into low, not with the lever, but by pulling the bare wire away from the downtube like a bow string. Tighten the inner limit until you can shift to low this way, but no further. Later you might fine tune this setting slightly if you have trouble shifting to low by the lever.

Now, go and see if it shifts to high properly. If not, odds are the high limit is too far in, back it off by quarter turns, keeping track, and see if that solves it. (It's best to push in on the RD slightly to take the load off the screw while adjusting).

OK, if it turns out both limits were off, it had nothing to do with your cable replacement, but does indicate a third problem. Your hanger is bent inward slightly, probably from dropping the bike. That moved the RD inward, throwing both limits off to the inside. You've now compensated, but at some point might want to have that corrected especially if the shifting isn't crisp and smooth.

You're actually lucky that you elected to replace the wire at this moment, otherwise you might not have noticed the inner limit/bent hanger problem, and could have shifted into the spokes causing expensive damage.

For future reference, you might want to do an inner limit safety check from time to time, especially after a crash, using the bow string method.
 
#3 ·
It looks like you are correct about the bent rear der concept.

I tried playing with the cable barrell adjuster but no luck. So I gently pulled outwards on the the der arm (cage?) and it now shifts to all cogs!

I am going on a 30 miler tomorrow and see how it acts under a load but I rode a little tonight and it worked fine so I'm cautiously optomistic.

Thanks a bunch!
 
#4 ·
Next time you want to pull out the hanger, don't pull on the RD itself. Stick a 6mm key in the mounting bolt and use that to bend the hanger.

Also before you go on that ride, make sure the inner limit screw is set so that the RD cannot overshift beyond the low gear sprocket. Set it based on pulling the wire directly, not the lever because often the last click hides the fact that the RD could move farther, if the cable were pulled more.
 
#5 ·
Sounds like your cable is too tight, probably because the shifter was in the wrong gear when you connected the cable. Disconnect the cable at the derailleur, and spin the pedals. It should automatically go into the smallest cog, if not, then you need to adjust the limit screw. Then push on the derailleur body all the way towards the spokes, you should be able to shift into the largest cog without going over. If it goes too far, or not far enough, you need to adjust your limit screw.

Once limits are set, use the shift lever to shift into the highest gear, and pull the cable taut, to remove the slack, and reconnect to the derailleur. From here, you should be fairly close, and can use the barrel adjusters to fine tune it.
 
#9 ·
What steelbikerider is referring to is the little washer with a tab under the rear derailleur cable fixing bolt, this tab has to be in the correct position when you tighten down the cable or it will hit the derailleur cage and cause the exact problem you are describing.
 
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