Front Derailleur - cable, mech or shifter problem

Tjgoodhew

Out for a quick spin last night and tried to change down from the big ring to the small ring and nothing. Tried again, still nothing.

It seems the cable has lost all tension. Turned barrel adjuster to add tension and still nothing. Its like the FD is simply stuck in the big ring position. I quickly looked at the cable at both the FD and the shifter and there isnt a noticeable breakage or snapped cable. The shifter clicks into positions fine and there seems to still be tension at the shifter end. I can move the FD with my hand but it is very stiff but there is next to no tension at the derailleur end

It has been working perfectly for 4000 miles so it isnt something that has deteriorated over time however the cables and front mech havent been changed in this time. Both parts are tiagra

I want to try and fix myself so just after any ideas what it could be and what i possibly need to buy.

My thought process is to properly clean the FD as it is a bit mucky , then change the cable. If that doesnt solve the problem then a trip to the LBS

gozzy

If there's no tension in the cable and it's stuck in the big ring then there's something wrong with the FD as it's untensioned position is the little ring, if there was a cable fault you'd not be able to get off the little ring.
I'd disconnect the mech, give it a clean, check it's positioning, check the cable while it's loose, then reattach it all and see what happens.

Tjgoodhew

Thanks Gozzy.

So best to focus my attention there. With that in mind it could be that its just covered in muck and needs a good clean.

I am upgrading the groupset in spring so i have been a little lapse on properly cleaning this winter

wishitwasallflat

As said FD goes to small from big ring under its own spring tension so the only way it could be a cable or STI problem would be if cable wasn't being released to allow the FD spring to pull it back when you shift down on the STI. Disconnect the cable and test the FD itself and hold the cable and feel what happens as you shift up and down on STI. That should id what's at fault. If its the FD it could well be ok with a proper clean and lube but I had an Apex (similar level) FD that was still sticky after that so replaced. Good news is that FDs are (relatively) cheap and work well if you can live with lower spec ones.

keef66

My front 105 5603 shifter failed recently. It wouldn't hold cable tension so it left me stuck in the smallest chainring (triple). With the cable disconnected from the mech there were no clicks going on in the shifter. I'm thinking the pawl's broken, possibly because I'd had too much cable tension.

Luckily bagged a used shifter off Ebay which seems to have the requisite number of clicks. OK, it's black and the other one's silver, but for £26 I'm not complaining. Will set this one up more carefully...

Your problem of being stuck in the big ring sounds odd. You need to detach the cable from the mech and see if the mech can be easily moved by hand. At the same time try the shifter to see if it's pulling / releasing the cable with each click (maintain a bit of tension on the cable by pulling it while you operate the shifter, otherwise you risk unseating the nipple from it's location in the shifter)

k-dog

This time of the year the first thing I would always suspect is just a gummed up FD. You can try and clean it but in my experience by the time they get that bad you'll never get it back to perfect - a new one will feel a ton better.

You should be able to get it functional again with a soak in oil though.

keef66

All my previous attempts to free up seized front mechs have resulted in only temporary improvement. Given how cheap they are nowadays I'd just buy a new one and spend my time on something more rewarding like riding the thing.

desweller

Sounds like the front mech's seized as the others have said.

I've successfully recovered them in the past with liberal (REALLY liberal) doses of WD40 and patient waggling of the mech over its travel.

dj58

Take the FD off the bike and given a good clean then submerse it in Plus Gas for a few hours and see if it frees up, if it doesn't it is new FD time.

macleod113

had a similar issue recently. tried cleaning the FD but no joy. looked on wiggle and a new FD was £15 so simply got a new one. problem sorted. i'm guessing moving parts done like winter!

Tjgoodhew

As all of said it was the FD. Took it off and the springs and pivot were caked in crap.

Didnt bother trying to clean it - straight in the bin and fitted a nice new one with new cables.

It was my first time fitting a FD so took me a while to line up and eliminate chain rub but its now shifting perfectly again

itboffin

its a bit late now as you've replaced it but i would have said that a FD stuck in the big ring must be something to do with the H/L screws stopping the mech returning to its natural position.

k-dog

^very unlikely for the screws to move that much - and it's much more likely to just be gummed up. The obvious way to test is to see if it moves when you push it. When mine has got like this I could push it down to the small ring and then the lever throw was enough to overcome the stickiness to get it back to the big ring - but then I'd have to stop to push it back down when the small ring was required.

itboffin

Depends how much troubleshooting messing around has gone on