Front derailleur reluctant to change up recently

For discussions about bikes and equipment.
LittleGreyCat
Posts: 766
Joined: 7 Aug 2013, 8:31pm

Front derailleur reluctant to change up recently

Postby LittleGreyCat » 25 Jun 2020, 5:43pm

On the last couple of rides the FD has been reluctant to change up into the biggest ring.
3 * 9 transmission.

I have STI shifters and what looks like a knurled adjuster (but it may just be an end for the outer) where tube down shifters would be.

If so, should I be twiddling the adjuster or twiddling the high screw on the FD?

Jdsk
Posts: 884
Joined: 5 Mar 2019, 5:42pm

Re: Front derailleur reluctant to change up recently

Postby Jdsk » 25 Jun 2020, 5:48pm

You need the limit stops set correctly.

After that you can adjust the cable tension, and maybe some other bits.

Jonathan

PS: Does the changer move further when you twiddle the appropriate stop after shifting as far as possible towards it?

User avatar
Paulatic
Posts: 5119
Joined: 2 Feb 2014, 1:03pm
Location: 24 Hours from Lands End

Re: Front derailleur reluctant to change up recently

Postby Paulatic » 25 Jun 2020, 6:18pm

If it’s been working alright until recently and nothing has been knocked then surely the cable has gone a bit slack?
Whatever I am, wherever I am, this is me. This is my life

https://stcleve.wordpress.com/category/lejog/

rotavator
Posts: 454
Joined: 6 Jun 2016, 9:50pm
Location: North Wales

Re: Front derailleur reluctant to change up recently

Postby rotavator » 25 Jun 2020, 6:25pm

Can you move the FD easily by hand? If yes, tighten the cable. If not, check the top limit screw. If it still doesn't shift there is probably something wrong or stiff in the FD.

User avatar
cycleruk
Posts: 5346
Joined: 17 Jan 2009, 9:30pm
Location: Lancashire

Re: Front derailleur reluctant to change up recently

Postby cycleruk » 25 Jun 2020, 6:28pm

The screws on the FD are not adjusters. They are just "stops". They stop the FD from shifting the chain over the big ring or dropping off the small ring. As Paulatic suggests if it is a new problem then cable or the FD has moved. Another slightly possible answer is the chain is worn. A worn chain bends easily and resists being moved onto the big ring.
There's no such thing as a tailwind.
It's either a headwind, or you're going well.

LittleGreyCat
Posts: 766
Joined: 7 Aug 2013, 8:31pm

Re: Front derailleur reluctant to change up recently

Postby LittleGreyCat » 25 Jun 2020, 7:22pm

cycleruk wrote:The screws on the FD are not adjusters. They are just "stops". They stop the FD from shifting the chain over the big ring or dropping off the small ring. As Paulatic suggests if it is a new problem then cable or the FD has moved. Another slightly possible answer is the chain is worn. A worn chain bends easily and resists being moved onto the big ring.


New chain, 3rd time out, I think.
First lubrication after factory improved things briefly but then the problem returned part way through the ride.

rmurphy195
Posts: 1754
Joined: 20 May 2011, 11:23am
Location: South Birmingham

Re: Front derailleur reluctant to change up recently

Postby rmurphy195 » 25 Jun 2020, 9:20pm

Paulatic wrote:If it’s been working alright until recently and nothing has been knocked then surely the cable has gone a bit slack?


Or maybe a bit of grit got under the top limit screw?
Brompton, Condor Heritage, creaky joints and thinning white (formerly grey) hair
""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !

hemo
Posts: 775
Joined: 16 Nov 2017, 5:40pm
Location: West Sussex

Re: Front derailleur reluctant to change up recently

Postby hemo » 25 Jun 2020, 11:32pm

Might just be something simple as cable stretch, check for any cable slack when on the smallest chain ring.

Jupestar
Posts: 17
Joined: 29 Feb 2020, 3:03pm

Re: Front derailleur reluctant to change up recently

Postby Jupestar » 25 Jun 2020, 11:49pm

LittleGreyCat wrote:New chain, 3rd time out, I think.
First lubrication after factory improved things briefly but then the problem returned part way through the ride.


Has this started since the new chain? Could be the FD doesn’t like the new chain. Is it the same speed chain?

iandusud
Posts: 329
Joined: 26 Mar 2018, 1:35pm

Re: Front derailleur reluctant to change up recently

Postby iandusud » 26 Jun 2020, 8:10am

Check the condition of the cable at both ends. If it's starting to fray the travel will be reduced giving those symptoms, followed by catastrophic failure!

ANTONISH
Posts: 1820
Joined: 26 Mar 2009, 9:49am

Re: Front derailleur reluctant to change up recently

Postby ANTONISH » 26 Jun 2020, 2:37pm

I had this same problem.
I found that the wires of the outer housing had pushed through the plastic end ferrule - the extra force needed to go onto the large ring made the wires slide through the cap and consequently it was reluctant to change.
I changed the plastic end cap for metal. Brucey suggested that preparation of the outer housing should include grinding the ends square.
As others have said the inner cable may be slack - maybe check that first.

hamster
Posts: 3497
Joined: 2 Feb 2007, 12:42pm

Re: Front derailleur reluctant to change up recently

Postby hamster » 26 Jun 2020, 4:20pm

Finally check the crank bolts are tight. Loose cranks move away from the mech.

LittleGreyCat
Posts: 766
Joined: 7 Aug 2013, 8:31pm

Re: Front derailleur reluctant to change up recently

Postby LittleGreyCat » 29 Jun 2020, 12:43pm

Well, it seems to have been the limit screw, associated with a slightly slack cable..

(1) Changed to lowest front cog, checked changing. Indexing went all the way up with 3 clicks for top gear but failed to change up to largest ring.

(2) Changed down to lowest front cog, felt tension of cable with finger. A bit slack (but I had previously been twiddling the cable adjuster to no apparent benefit).

(3) Twiddled the cable adjuster to take all the slack out of the cable. Tested, and indexing only clicked twice for the top ring. Hmmm......something stopping the 3rd click?

(4) Twiddled the stop screw out about 1 full turn and then tested. Now changing up with 3 clicks. Twiddled it another half turn for luck, and tested changing up from large rear cogs as well as small ones. All seems good. Will fine tune on the road over the next couple of rides.

So that leaves me with the question "Why did it stop working and what has changed?".

As far as I know I haven't belted the FD on anything (quite hard to do, I imagine) so why does it suddenly go out of whack after 18 months of sterling service?

Brucey
Posts: 39500
Joined: 4 Jan 2012, 6:25pm

Re: Front derailleur reluctant to change up recently

Postby Brucey » 29 Jun 2020, 1:15pm

could the chainrings have moved to the right for any reason?

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

LittleGreyCat
Posts: 766
Joined: 7 Aug 2013, 8:31pm

Re: Front derailleur reluctant to change up recently

Postby LittleGreyCat » 29 Jun 2020, 5:40pm

Brucey wrote:could the chainrings have moved to the right for any reason?

cheers


Difficult to work out how.

I will double check there is nothing adrift.

I did remove and replace the bottom bracket as part of the general once over, but that was a while back and the gear change problem has only just manifested.