Front derailleur will not change onto largest (52) ring

[MartinC]

Undo the cable. Move the mech by hand and see if it goes far enough to shift on to the big ring. If it doesn't the cable has naff all to do with the problem (i.e. it's the limit stop, chainline or seizing). If it does then it's not enough cable pull (adjustment, sticky cable, wrong mech, shifter broken). You can theorise as much a you like but if you want to solve the problem you have to systematically eliminate possible causes. It isn't rocket science.

[gaz]

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[mark a.]

I'm reluctant to move the stop as Itry to work on things like this by a process of elimination if it ain't broke don't ( try) to fix it.

But something is broke, so something needs fixing. And how can you do things by process of elimination if you're not starting at one of the most basic points?

Moving the stop temporarily has zero effect on the rest of the system, unlike your constant fiddling with cable adjusters and things like that. It's also really really easy - unscrew a turn or two, then you can screw it back in to where it was if needed.

Start with the simplest options and then start worrying about index adjustment, cable health etc.

[gregoryoftours]

You're not likely to get anywhere until you try different things as lots of people have suggested. Move the front mech with your hand. If you can get it to shift onto the big ring reliably using your hand then the problem is not the mech, it's probably with the cable or shifter, (unless the fd pivots have slop in which case it could possibly be that). If it doesn't shift into big ring with your hand then the problem is either with the mech, chainset or bb etc, either H limit screw or various other possibilities that people have mentioned. Take some photos and post them.

[Manc33]

If you do undo that limit screw a bit and do get it to shift... make sure the front mech cage isn't then going to get hit by the crank arm. This is one reason why you'd say "if it ain't broke don't fix it" lol.

On my front mech on the outer (also a 52t), I can push the front shifter and move the mech about 1mm extra but, it isn't near the crank arm when I do that. Because of my "fussy" setup, I have to push the lever fully to shift up from middle to outer but it works, its a key thing - just "clicking the shifter" and expecting it to shift up might not be making it shift up. Have it setup so it needs a full push. With the granny to middle shift this is even more true, is on mine anyway, triples: can't live with them, can't get up hills without them.

[MikeF]

I have to push the lever fully to shift up from middle to outer but it works, its a key thing - just "clicking the shifter" and expecting it to shift up might not be making it shift up. Have it setup so it needs a full push.

That's a good point. The FD may need to move initially a little bit farther to the right so the chain can climb onto the big ring - maybe the shifter needs pushing as far as it will go for a little longer to achieve this.

[reohn2]

I have to push the lever fully to shift up from middle to outer but it works, its a key thing - just "clicking the shifter" and expecting it to shift up might not be making it shift up. Have it setup so it needs a full push.

That's a good point. The FD may need to move initially a little bit farther to the right so the chain can climb onto the big ring - maybe the shifter needs pushing as far as it will go for a little longer to achieve this.

Known as overshifting,STI's are good for this particularly when changing up to a bigger ring/cog as there's the facility overshift after the click and if the limit screws are set right it's almost impossible to overshoot the big ring.
It's the reason I advised the OP to only back off the outer/big ring limit screw by quarter of a turn.
If it's not quite changing up onto the outer/big ring quarter of a turn should be enough of overshift without throwing the chain off altogther.

[QUIST]

Thanks for all your heklp and suggestions.

I eventually took the bike to the helpful LBS whoafter fiddling asround with the cable and the screw stop could not get it to shift across. He then took another look at it and advised it was worn out as the shift plate had been bent out of shape after many years of use.

He then proceeded to fix it by bending said plate so it now moves with no problems, but I fear it won't be fixable again so would like another deore shifter

The LBS owner really is an mazing guy I'm sure other shops would have said its not repairable whereas he did so-I shouldn't be too surprised he has built 3 bikes for over the years - all one off specials

[Brucey]

glad you have an answer now, but if you had posted a picture of the thing you might have got there three pages ago....?

cheers

[mjr]

glad you have an answer now, but if you had posted a picture of the thing you might have got there three pages ago....?

or responded to any of the five people on page 1 asking/suggesting whether it's in line/parallel...

[QUIST]

I don't have the trec necessary to post p;ics and as far as I could see it was in line