[stock_tires]

Ok, ive been trying to adjust my derailleur....and its not working to well. It wont quite go into first gear unless im going very slow, and it shifts straight from 2nd to 4th. My derailleur is a shimano, my bike is a 21 speed. The front derailleur is working great, its the rear that is giving me a fit...and if im in 7th gear, going fast, it has this nasty little habit of jumping out of gear and laying me flat on the road.

Someone please help me before I throw this POS in a trash can...

BTW- it has 2 limit screws on the side and one screw on the backof the deraileur if it helps anyone.

 

[Willy Vanilly]

I'm guessing that your limits need some adjustment. Turning the limits clockwise will decrease the range of motion of the derailleur (bringing the limits in... towards the center of the cogs). The low limit should allow you to fine tune the range of motion of the derailleur approaching 1st gear. Try backing it out (counterclockwise) maybe a 1/4 to a half turn and ride it. If the problem persists try another 1/4 turn. For the high limit, try bringing it in a 1/4 turn (clockwise).

Your cable sounds like it might be a bit loose. Fiddle with the barrel adjuster (on the back of the derailleur itself or at the shifter). Counterclockwise turns of either will take up slack in the cable and should help the 2 to 4 jump.

Good luck. Make small adjustments to the limits. Clockwise to keep the derailleur more centered, counterclockwise to let it move out further.

 

[stock_tires]

Thanks willy, is there any way to tell which screw does wich operation? other than just trial and error?

 

[BikeGeek]

This should help explain what's what and how to adjust it:
http://www.parktool.com/repair/readhowto.asp?id=64

 

[Willy Vanilly]

Sometimes the screws will be marked "H"igh and "L"ow. Other than that you have a 50/50 chance. If you do have to guess though, make sure the derailleur's in the biggest or smallest cog. Watch for movement from the back of the bike looking forward (sighting down the chain). Go slow with the adjustments on those limits and keep track of how far you've turned so you can set it back if you get bungled up. Good luck

 

[Dartman]

Check your cables for smooth action as well. They could be gunked up or kinked.

 

[zebrahum]

If the limits are off, then the deralieur or deralieur hanger is almost certainly bent. Stand behind the bike with it leaning up against a wall and see if the two little pulleys are in a perfectly straight line with the cassette. It usually helps if you shift both the front and back into a middle gear. If it's bent a shop should be able to bend it back or get you some new parts if it's bad.

 

[Green Flame]

Pull out the cable from the housing. Clean w/ some steel wool, lubricate w/ some rock n roll lube or just a little bit of Park grease. reinstall, check your alighnment on your hanger and drink a cold one.