Rear derailleur not reaching lowest gear

[tenthsphere]

I've just gotten into bicycling, complete with picking up a used bike. I've manage to do some basic stuff, like tuning the brakes and such with decent success. I even managed to get the front derailleur working (not sure if it's perfect, but it's going). However, I've hit a snag on the rear derailleur and was hoping someone here might be able to help get me on the right track.

My the rear D works for shifting from one gear to the next except for the lowest (largest, which I think is the lowest) gear. Once I get to the second the lowest, it stops. And pushing the gear shifter meets resistance, like it does not think there is another gear to even go to. No amount of fiddling with the limit stop screw moves it one way or the other.

Now, if I shift up to high (smaller) gears in the back, it can go all the way to the smallest. Once there, it allows me to click it AGAIN as though it thinks there IS another gear even smaller. But it just stay where it is, because there obviously isn't one.

As such, I'm pretty sure it's gotten misaligned somehow. Can someone help point me in the proper way to fix this? I'm very scared to actually unscrew the bolt holding the wire tension, as I'm worried I'll never get it working again. Is that what has to be done?

Thank so much

[Jordan300]

Of course, the rear derailer has, what are called limit screws. High and Low. You probably need to lossen your L screw a bit so that it can reach all the way down. And of course, answering this question with out linking you to this would be incomplete
http://www.sheldonbrown.com/derailer-adjustment.html This will help you if that fails.

[tenthsphere]

Jordan,

Thanks for the link. I'm going to read it now and see if it suggests some help.

As to your suggestion, when it is in the lowest (largest) gear it can reach (it never hits the largest, that's my problem) the limit screw does not move it at all in either direction.

[jr14]

When the limit screws stop doing anything, I usually back out the limit screws, loosen the bolt and let the cable go slack. and then start over. Pretend its a fresh install.

1. Check the cable tension, and make sure all the cable housings are properly seated in their stops.

2. Turn the barrel adjuster all the way loose, then back out 1 full rotation.

3. Then pull the cable tight, and tighten the bolt again.

See where that leaves you. If you are in the same boat afterwards, turn the barrel adjuster in the direction you want it to go. In your case, turn counter clockwise towards the wheel. This will tighten the cable and hopefully get it into that last gear.

Good Luck!

[Aushiker]

Hi

I had the same problem yesterday actually when I was trying to retune my RD after a cable replacement. What I found was that my cable tension, which I thought was good initially, was just not tense enough and that I had to pull it that bit more to get the range of adjustment I needed. I used a fourth hand to apply that extra bit of tension.

Good luck on getting it fixed.

Andrew

[John K]

I have sort of the same problem. The adjusting screws just don't do it.
My bike has lost its' range of gear shifting. I can adjust it to get the lower 4 gears, or the highest 4 gears, but not all.
I don't think the hanger is bent but am up for any suggestions.
Thanks,
John

[BamaBraves]

The screws are to prevent the chain from going past the first gear and the sixth gear.

You can do miner adjustments at both ends of the cable. These adjustments are to move the derailleur slightly. To make the chain quitter when peddling.

The adjustment you need to make will be with the cable. I use locking pliers to help with this. I clamp on to the cable at the nut before loosing the nut. This makes it easier to adjust the derailleur.

I usually put the gear shifter on 6. Then I turn it to 5 while turning the peddles. If nothing happens, I adjust the cable accordingly. Then go back to 6 on the shifter and test it again. If OK, then go to 4 and so on.

Remember to reposition your locking pliers on the cable. This will act as a marker as well.