derailluer wont move into top gear

[rymoto]

I can't get my rear derailleur to shift into top gear. the unit seems to move inline with the gear but the chain doesn't even begin to transfer over. It will randomly move into top gear somtimes, though I cant figure out what trigger's it. I might try to loosen the control cable and see if that helps. Has anyone had this problem?

 

[jhuskey]

Probably a cable tension problem. There should be a barrel adjustment near the rear derailleur in line with the shift cable.
Set the bike on a work stand or hang it from the ceiling wher you can see the derailleur easily move the crank and shift while adjusting this barrel.
You should be able to get a smooth shift up and down in all gears and you will get better at it with practice.
This is most likely the problem but not 100% of the time just 99%.

 

[capwater]

Most likely a tension issue, 1/4 turn to the right. Could also be a bent derailler. You bang it up recently? If it has never gone up well, then look for a limit screw adjustment to take place.

 

[daveornee]

I can't get my rear derailleur to shift into top gear. the unit seems to move inline with the gear but the chain doesn't even begin to transfer over. It will randomly move into top gear somtimes, though I cant figure out what trigger's it. I might try to loosen the control cable and see if that helps. Has anyone had this problem?

http://www.parktool.com/repair/readhowto.asp?id=64
What happened last that might have changed the function?
(fall on the right side of the bicycle, transport where the right side was hit, etc.)

 

[rymoto]

I have always had the problem while I've had the bike. My dad had it for at least 10 years so Im sure at one point it has been dropped. I'll try playing with the different adjustments and see what happens

 

[Retro Grouch]

I can't get my rear derailleur to shift into top gear. the unit seems to move inline with the gear but the chain doesn't even begin to transfer over. It will randomly move into top gear somtimes, though I cant figure out what trigger's it. I might try to loosen the control cable and see if that helps. Has anyone had this problem?

I doubt it's cable tension. Cables never get tighter, only looser. A too loose cable wouldn't be able to access the biggest rear cog.

Likely possibilities are a bent derailleur hanger and a worn cable housing adjacent to the rear derailleur.

 

[gclark8]

I would disconnect the cable at the derailleur and adjust the High Limit Screw First.

Then,
screw in all the RD cable adjusters,
reconnect the cable
and shift the lever to second top.
Then adjust the barrel adjuster until the derailleur starts to engage the next gear.

 

[david462]

first and last gears have a special screw adjustment (this is to limit the derailler from moving the chain too far so it pops off the cog and gets stuck between the frame or wheel).

there should be a pair of screws on the derailler. they might each be labeled with an "L", for low and "H" for high. your going to want to unscrew the high screw as you turn the cranks by hand and see if it goes to last gear. if not adjust the cable by turning the barrel adjusters clockwise.