6-speed adjustment
 

Hi guys. I just got my hands on an older bike with Shimano 6-speed gears. I have made it shift nice and smooth between the first five gears, but no matter what I do, I can't get it to move down to the last gear. I have messed around with it for hours now, and am pretty damn annoyed! :D
So what could be a possible fix? I have adjusted everything there is to adjust, but it just won't go onto the last cog. The bike is in very good condition, and I don't thing anything is broken. So I am running out of ideas. :)

Make sure that the L adjustment screw isn't preventing it from going into the top gear.

Shift up to the sixth, and if one of the screws is touching the derailleur body, you need to back it off a bit, and shifting should work fine after.

Hi, Limit screws ? rgds, sreten.

[1] Release the gear cable from the rear derailleur
[2] Crank the pedal and tune the H setting screw. If it is too far out, it will drop off the freewheel. If it is too far in, it will feel rough and may be on the 5th gear position. Tune until it feels smooth.
[3] Connect the gear cable. Make sure the shifter is in the correct position at gear 6. Cable tension should be tight when it is being connected.
[4] Shift the gears one at a time. If it doesn't go up, check the cable tension, too much slack will prevent the chain from going up to the next gear. Minor slack adjustments can be tightened by the barrel adjuster on the derailleur.
[5] Shift up to the lowest gear (the biggest cog). If it doesn't go up, loosen the L setting screw. If this is loosened too much, the chain may come off onto the spokes.Adjust until it is able to go there without going over.
[6] Try all the gears up and down a few times.... and if the cable stretch, take up the slack with the barrel adjuster. If it doesn't come down, try to loosen the cable tension with the barrel adjuster.

The fix depends partly on what you mean by the "last gear" - the largest cog or the smallest. The easiest way to confirm proper travel to both ends is to disconnect the cable and shift by pushing on the derailleur as you turn the pedals to go to the large cog and letting go to get to the lowest. If the derailleur fails to go to the smallest or largest cog the problem is either limit screws or the derailleur/hanger. The screw labled H controls the small cog limit, L the large cog, and each is unscrewed to allow more movement in that direction. If backing them off does not solve the problem then most likely the derailleur/hanger is bent in (smallest cog) or the derailleur capacity is smaller than the cog size (largest cog). If it moves fine with the cable disconnected then logically the problem is with the cable - either too little tension (large cog) or too much friction (small cog).

Thank you for all your advice! I removed det cable, and it went down to the small cog as it should. So the problem must be the cable is too tight or what? :)

The only thing that shifts the derailleur to the small cog is the spring on it pulling the cable through the housing, so you need to start with making sure the cable is lubricated and not rusted. If there is any rust where the cable is inside the housing you need to replace it, preferably the housing as well. Google install shift cable. When done Google adjust rear derailleur. Sheldonbrown and parktool usually offer the best advice.

Hi, Sounds like the cable was fitted too tight, easy fix. rgds, sreten.