Sticky front mech?

[mynydd]

Hi,
I'm having problems with my front mech. It won't shift down onto the small cog. The cable tension is correct, and not too tight. It's as if the mech is sticky with road muck and won't go all the way on it's own. I've taken to unclipping and tapping it gently with my right foot to shift down.
It's tiagra. I use my bike daily in all weathers, about 100 miles commuting a week.
I've taken it off cleaned it with de greaser, oiled it and put it back, it's still the same.
Is this a "thing" ? if so how do I remedy it.
Or do they simply wear out? And need replacing.
I've ridden this bike every weekday for three years........
Thanks in advance

 

[boydj]

Could be the cable that's sticking, possibly in the shifter, where the cable can get frayed over time. Check in the shifter.

 

[mynydd]

Thanks, I changed the outers and cables about a month ago. Was working beautifully. Then I put the bike away over Christmas, and it's not been great since. Cables was my first suspicion, but they're fine. It's the mech that seems to be sticky.... if that makes sense.

 

[Rickshaw Phil]

Which way does the cable run to the derailleur? If under the bottom bracket, is there dirt in the guide?

 

[mynydd]

Thanks, Yes, I've cleaned it.
I'm sure it's the mech. As when I attempt to shift down the cable near the mech goes slack, but the mech doesn't move all the way down..... I have to push it, manually, then the chain easily drops onto the small cog.

 

[gbb]

I can't visualise a Tiagra FD but certainly my Sora FD used to suffer every winter when commuting, if a Tiagra FD has its main pivot screw (on Sora it's a large dome headed Allen screw, chrome plated)...pointing rearward, loosen that screw NOT remove it, and get some WD or similar into it, work it, manipulate it then tighten back up. Used to solve it every time...till next year. Perhaps some grease or anti sieze once it's free would help.

 

[Rickshaw Phil]

Failed return spring?

 

[mynydd]

I can't visualise a Tiagra FD but certainly my Sora FD used to suffer every winter when commuting, if a Tiagra FD has its main pivot screw (on Sora it's a large dome headed Allen screw, chrome plated)...pointing rearward, loosen that screw NOT remove it, and get some WD or similar into it, work it, manipulate it then tighten back up. Used to solve it every time...till next year. Perhaps some grease or anti sieze once it's free would help.

Thanks, no such screw on this though....

Failed return spring?

That's what it feels like.... is that fixable, easily? Or is it new mech time?

Thanks both

 

[KneesUp]

Does it go far enough without the cable attached? That would eliminate the cable entirely.

 

[mynydd]

Does it go far enough without the cable attached? That would eliminate the cable entirely.

No it doesn't, unless I push it, which is why I suspect the issue is with the mech, thanks.
Just looked on eBay, seems I can pick a new one up for 15 quid, so might just do that.
Unless anyone has a fix?

 

[Rickshaw Phil]

.....
That's what it feels like.... is that fixable, easily? Or is it new mech time?.......

It's not something I've ever had fail or tried to replace. Might be a new mech unless anyone knows better.

 

[KneesUp]

No it doesn't, unless I push it, which is why I suspect the issue is with the mech, thanks.
Just looked on eBay, seems I can pick a new one up for 15 quid, so might just do that.
Unless anyone has a fix?

I had one that was sticky from a rescued bike. I just soaked it in oil for a few days then spent ten minutes or so putting it through the full range of movement manually (i.e. by hand rather than with the cable) It was fine, but I didn't need it on a bike I rode daily. For £15 I'd suggest a new one, then stick the old one in oil and revive it so you can swap over again next winter

 

[lpretro1]

If it will only move when you push it then it is highly likely the pivots have corroded and if no matter what you lube them with it still won't work then new mech time. They are not expensive

 

[fossyant]

I would go with a deep clean - take it off and fully inspect it. Mechs rarely fail, and you've either got some corrosion or dirt in there. If the spring has broken, it's a new one.

My mate killed his Deore XT front mech by never squirting GT85 or similar on it - killed it in one winter.

 

[raleighnut]

I'd go for the 'oil it and work it by hand' but I'd sooner repair than replace if I can.