Fine tuning barrel adjustments / limit screws

[Fishbike]

I can usually adjust my rear derailluers by trial and error. But I would like to understand better what adjustments are needed for what issues. So. . .

Turning the barrel adjuster toward the spokes will fix what issues and why?

Turning the barrel adjuster away from the spokes will fix what issues and why?

If the chain skips cogs going up -- into a lower gear -- I should. . . . .

If the chain skips cogs going down -- into a higher gear -- I should. . .

If the chain won't jump into the lowest gear / biggest cog I should. . .

If the chaim is rubbing on the highest gear / smallest cog and the chain stay I should. . . .

Wrench in Training

[Louis]

I think the best way to think of it is "What causes the housing to be longer?" (that therefore tightens the cable and therefore causes the cage to move in X direction - depends on whether the R-der is Hi or Low Normal) and what causes the housing to be shorter, and therefore slacken then cable.

Since the barrel adjuster has a right-hand thread you can figure out what causes the housing to become longer, and what causes it to become shorter, and therefore figure out how the cage will move.

Your way of thinking about it may vary.

[Charles M]

Put your bike in a stand.

put it in the large ring and the middle gear.



Start turning the adjuster on the rear DER one way untill you start to hear the chain clicking/making noise like it's rubbing.


Stop and go in the other direction counting your twists till the sound goes away AND COMES BACK (meaning youre starting to hear the chain jumping - clicking against the gears again.

Take the number of twists and cut it in half and that should be your center of adjustment.


If you then struggle to go up gears (larger), take a turn counter clock wise. Do the opposite (Clockwise) if you struggle to go to smaller gears.

The general struggle is to go to bigger gears versus smaller from the center of adjustment...

[Pete Serotta]

I am going to do that to my bike later today. PETE :D

[flydhest]

I liked Pez's answer, but here's a different wording of it--I always find it useful to hear more than one way of saying the same thing.

The barrel screws in or out, effectively shortening or lenghthening the cable, which effectively reduces or adds tension to the cable.

For a rear derailleur, the spring will put the derailleur all the way to the smallest cog (biggest gear), so the cable pulls it to the bigger cogs (smallest gear). Tension on the cable pulls the derailleur to the bigger cogs.

If your bike is not shifting easily to bigger cogs, you need a bit more tension on it. If it is not shifting to smaller cogs, you need a bit less tension on it.

[Jawn P]

For limit screws, I will set before tensioning the cable. Push the derailer with your thumb to simulate upshifting, adjust low limit so you don't shift into your spokes. Adjust high limit to ensure that derailer is in line with your smallest cog.

[hmsolomon]

1 chain needs cleaning and lube
2 cable and/or housing needs replacement
3 cassette is worn so replace chain and cassette

[Kontact]

I'd recommend the horse's mouth, then questions:

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Ultegra/SI_5VG0C_001/SI_5VG0C_001_En_v1_m56577569830616226.pdf

[EmoryDPTT]

Zinns Art of Road Bike Maintenance.
Great book to have. Recommended to anybody that likes to work on bikes.
http://www.google.com/products/catalog?q=zinn+bike+maintenance&rls=com.microsoft:en-us:IE-SearchBox&oe=&um=1&ie=UTF-8&tbm=shop&cid=10796322757343436414&sa=X&ei=-Z0LT9rmJMy2tweAz7DoBQ&ved=0CDsQ8wIwAg#