Frozen front mech

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Hackfall
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Frozen front mech

Postby Hackfall » 24 Aug 2016, 9:18am

I have increasingly had issues with my front mech, my setup is a hybrid that has been good for over a decade, front Veloce 9 speed levers, and front shimano exage mech. Now for a few weeks the mech has refused to move from the outer to the inner ring without a few taps of the foot. washing and lubing has not helped. Now it won't move from inner to outer either. The cable seems ok, I have not changed it yet in this process. My next move was going to be to take the mech off and soak it in something (oil?) and then see if it releases as I presume that if it is functioning correctly if you push it out then let go it should drop down again. Failing this I am not sure I can do anything other than get new levers and front mech. I am going to look to put a 105 5800 group on eventually but was not quite ready to start forking out yet.

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DaveP
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Re: Frozen front mech

Postby DaveP » 24 Aug 2016, 9:44am

That does seem a bit odd! You say you have washed it, so we can take it for granted that it's not jammed by a big clod of mud. :D The pivots are nothing more than a pin going though holes in sheet metal - so unless the whole thing is a mass of scaly rust I can't see rusty pivots causing this.
Is it possible that the whole thing has been deformed by some external pressure - carelessly leant on something for example? Clutching at straws here, but distortion can make any sort of linkage misbehave.
Separate things by either disconnecting the cable or unhooking one of the outers from its stop, so that the cable is hanging loose.
What happens when you try to move the mech by hand?
Tension the cable lightly by figure pressure and operate the shifter. Can you feel the cable being drawn in and released?
Hopefully you will now have an idea of just where the problem is.
Cables are cheap. Mechs can be. But if it's the shifter - you might be as well to go for that upgrade...
Trying to retain enough fitness to grow old disgracefully... That hasn't changed!

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NATURAL ANKLING
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Re: Frozen front mech

Postby NATURAL ANKLING » 24 Aug 2016, 9:51am

Hi,
As said disconnect cable.
If part of inner cable is exposed just apply finger to that and watch the mech move.

Sounds like cable or lever.
NA Thinks Just End 2 End Return + Bivvy
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Brucey
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Re: Frozen front mech

Postby Brucey » 24 Aug 2016, 9:53am

It is possible that the cable is binding or perhaps has worn itself a tight-fitting groove in the BB guide and now won't slide freely, but you will most likely find that one of the front mech pivots has a large area bushing in it (normally the one under the spring or the one diagonally opposite) and that this pivot has seized up; the washing may have added the coup de grace to the seizure, especially if you didn't spray the front mech with a water-displacing lube after washing.

My suggestion would be to disconnect the cable, then spray the front mech with GT85 and then to work it back and forth by hand many times over, adding more GT85 as necessary. You will know that you are doing some good if one of the pivots bleeds black crud out of it as the mech frees off.

cheers
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Hackfall
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Re: Frozen front mech

Postby Hackfall » 24 Aug 2016, 11:27am

Thanks all i will look to these suggestions and hopefully get it moving again.

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.

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Gattonero
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Re: Frozen front mech

Postby Gattonero » 28 Aug 2016, 11:30am

Hackfall wrote:I have increasingly had issues with my front mech, my setup is a hybrid that has been good for over a decade, front Veloce 9 speed levers, and front shimano exage mech. Now for a few weeks the mech has refused to move from the outer to the inner ring without a few taps of the foot. washing and lubing has not helped. Now it won't move from inner to outer either. The cable seems ok, I have not changed it yet in this process. My next move was going to be to take the mech off and soak it in something (oil?) and then see if it releases as I presume that if it is functioning correctly if you push it out then let go it should drop down again. Failing this I am not sure I can do anything other than get new levers and front mech. I am going to look to put a 105 5800 group on eventually but was not quite ready to start forking out yet.


Remove the mech and leave it for a day soaking in WD-40, after that see if you can start moving it by hand.
It may need to wiggle it dozens of times, to get the pivots free; often it comes back to life.

If not, the FD is one of the cheapest parts, when you replace it you may want a new gear wire as well (I assume it was checked for smooth operation in the first place), so to get a fresh new start.
And every now and then, a drop of oil in the pivots is a good habit :wink:
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Hackfall
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Re: Frozen front mech

Postby Hackfall » 30 Aug 2016, 8:37pm

Its soaking now for a couple of days. Will check it in a day or so.
Out of interest here. The existing shifter is a 9 speed veloce. The mech is a shimano of similar vintage possibly rx100. The campag shifter is thumb shift to drop from big to small ring. Its multiple clicks to tighten the cable sufficient to move the mech (when it works). If i change to the latest 105 front mech (5800) will the current shifter work with it or will i need to go to 5800 shifters too?

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.

Brucey
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Re: Frozen front mech

Postby Brucey » 30 Aug 2016, 8:41pm

9s veloce LH shifter will work shimano front mech OK.

[edit; 'on a double'. But the cable pull is a lot more than you would have with an older front mech. TBH I'd use a shorter pull front mech than that. Remember that FD-5800 is for 11s and I think it has a narrow cage too, which could make for mucho scrapey-scrapey action with a 9s chain.]

cheers
Last edited by Brucey on 30 Aug 2016, 8:50pm, edited 1 time in total.
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Hackfall
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Re: Frozen front mech

Postby Hackfall » 30 Aug 2016, 8:42pm

Thanks Brucey think i may just go with that then. Not looking too hopeful for the old mech.

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.

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Hackfall
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Re: Frozen front mech

Postby Hackfall » 30 Aug 2016, 8:52pm

Is there much benefit in going ultegra 6800? They are only another 4 quid but is it worth it?

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.

Brucey
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Re: Frozen front mech

Postby Brucey » 30 Aug 2016, 9:01pm

see my post edit above; I'm not sure that using an 11s mech (with long cable pull BTW) is a great idea on a 9s system.

cheers
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Hackfall
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Re: Frozen front mech

Postby Hackfall » 30 Aug 2016, 9:35pm

Ok. Safer bet with sora 3500 9 speed then?

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.

Brucey
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Re: Frozen front mech

Postby Brucey » 30 Aug 2016, 10:07pm

yep, I'd have said so; the shift ratio is about the same as the campag mechs.

cheers
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hamster
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Re: Frozen front mech

Postby hamster » 31 Aug 2016, 8:02am

I had the same symptoms years ago on a Shimano mech of similar quality (300LX MTB). Essentially it seemed to corrode inside one of the pivot shafts and this rusted it solid.

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Hackfall
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Re: Frozen front mech

Postby Hackfall » 31 Aug 2016, 8:10am

I have ordered a sora now. Did not realise newer mechs would still work with my shifters. For 12 quid its a no brainer.

I'm a trendy consumer. Just look at my SM-A300FU using hovercraft full of eels.