Front Derailleur trouble

[Summerking]

The Front Derailleur on my old Raleigh will only shift back and forth between the small and middle ring, the derailleur isn't pushing the chain far enough over for the Biggest ring to catch it. The Deore/LX trigger shifter is at its maximum pull as the end of the cable is visible through a hole in the trigger housing. How do I adjust it so that it pushes the chain over further? I have a photograph below of the maximum reach of the derailleur with the trigger shifter pushed as far as it will go

and it's nowhere near close to the big ring.
I would be grateful for any advice.
Summer.

 

[Tim Hall]

Several things:

It looks like the derailleur isn't straight, leastways the trailing edge of the outer plate is out further from the chain ring than the leading edge. To adjust that, loosen the clamp bolt that holds the mech to the seat tube just a touch and ease it round. Tighten the bolt again.

If that doesn't fix it you need to make the mech go over further. To check it's not being restricted by the limit screw, what happens if you pull the cable itself, as it runs down the frame, rather than using the trigger to move it? If it changes to the big ring, you need to increase the cable tension, so the trigger can pull the mech over properly. Where the cable exits the trigger you'll see a barrel adjuster - a knurled knob that the cable outer sits it. Undo this half a turn and see if it does the job. If it doesn't do it, try another half turn.

If the cable pull by hand trick doesn't get the chain onto the big ring you need to adjust the limit screw. There are two of these, and you can see them in you photo. Undo the one marked "H" a quarter turn and see what happens.

Finally, have you ever considered lubricating your chain?

 

[Summerking]

hi Tim, pulling the cable by hand had the same effect as pushing the trigger shifter all the way. I have undone the High adjustment screw incrementally to see what difference it made and it moved the derailleur a tiny bit each time but the H screw is almost completely out and still nowhere near placing the chain where the big ring/cog will pick it up.
been riding a few years so normally my chain is lubed, this bike has only been mine for 2 days and this is how it looks AFTER cleaning..

 

[compo]

If I was doing it I would disconnect the cable from the mechanism then move the cage by hand and check it for swing range. If the cage wont move outward towards your big ring enough then all the pulling on the cable will achieve nothing and you will need to look elsewhere for your problem. It could be worth removing the mechanism from the frame so you can thoroughly clean and lubricate it and see why it wont swing through it's full range.

 

[Tim Hall]

OK. Have you tried twisting the mech so the trailing edge is parallel to the chain ring? And how high is the cage with respect to the big ring? It should be the thickness of a penny. See Park Tools article for more clues.

 

[Summerking]

Hi Tim and Compo I really do appreciate your time with this,
I loosened the clamp bolt sufficiently to line up the derailleur better as you said. The height of the cage in respect to the big ring is more like 5 pennies thick rather than one, I can see by the paintwork that the derailleur clamp hasn't moved in height in years.
I have now applied an aerosol penetrating oil gt85 whereas previously it was only wd40, to every moving hinge, cable end and trigger cable hole involved with the front derailleur and am leaving it to sit. Could the cables have stretched with age and use?

 

[compo]

Cables can stretch a little which is probably why Tim suggested pulling the cable itself. Once you have got the mechanism moving over it's full range then you can adjust the cable.

 

[wakou]

On some shimano front mechs the cable must go OUTSIDE the little tab thing on the cable clamp screw, then pull it round the screw itself, there is a slot/notch in the 'washer' part to guide it. It even looks like yours may be coming on the wrong side of the clamp screw..

ps http://www.bikeplus.co.uk/p/39516/BARGAIN-Inner-cable-set-2x-Gear-2x-Brake-Flat-Bar

 

[Summerking]

On Leaving the bike overnight sprayed liberally in penetrating oil I have this morning found that the Front shifter has 'acquired' a much more positive big ring movement and accompanying click, the front derailleur has an increased range to accompany this and it now pushes the chain far enough to catch the big ring, I have used the H and L adjusters at both Small and Big ring to prevent the chain falling off which it did at first.
I have a feeling the root of the problem was within the trigger shifter mechanism? itself where ordinary WD40 had made no difference but GT85 did. Hopefully all will remain well for the big ride tomorrow to Penzance.
Thankyou all for helping,having you here has encouraged me to attempt repairs/adjustments which previously would have gone to the LBS.
Summer.

 

[compo]

Good news and all the best with your ride.