Sora FD downshift stiff

[Vitara]

The downshift button on my FD has become increasingly stiff when moving from the large to the middle ring to the point on my last ride I couldn't release it with my thumb and on one occasion had to stop to downshift. Middle to inner chain ring is no problem, and upshift is fine.
I was due to change the cables anyway so have done this along with lubrication but the problem is still there.
I have tried suggestions revealed by google search; adjust cable tension and adjust H stop screw, neither seem to help.
I have found that pushing the upshift lever across then pressing the downshift button resolves the problem. This suggests the problem is that the button won't release under tension. Any suggestions as to how I can get the downshift to function correctly would be most welcome.

[reohn2]

If the cable and front mech itself are moving freely try flooding the STI with aerosol grease,TF2 or similar.
Has the STI had a knock,bike fell over,or crash recently?

[bazzo]

Hi,

I had a similar problem, I found that by not applying too much pressure on the lever when moving to a lower gear the problem ceased to happen.

[fatboy]

It sounds to me that the FD is hard against the H stop. Once in the big ring you should be able to waggle the FD a little bit. Does yours have the trim function (I have 2 bikes, 1 has trim and 1 does not (even thought the manual that came with the bike said it had!))? If you have it can you do the little trim?

To check to see if I'm right you can either move the H stop out a lot or adjust the cable back a lot. Obviously you'll have to re-adjust after all of this but better than having to buy a new shifter if there is nothing wrong.

[reohn2]

It sounds to me that the FD is hard against the H stop.................

It's the downshift ie;big to middle shift,that's giving the problem,if the mech is hard up again the H stop it'll release away from it.

I'd renew the inner cable first should there be a strand broken and digging into the outer cable,I've had this happen though with different symptoms.A new cable will sort it out.
Whilst the cable is off check if the front mech is going back to the inner ring under it's own spring tension and can be moved to the outer ring smoothly by hand,you may need to take the chain off or get someone to lift the rear wheel up whilst you turn the pedals andd change gear by hand on the mech watch your finger though .
If the mech is gummed up with muck clean and lube it,check it's not bent in any way or the spring isn't broken.
Also whilst the cable is off check the operation of the STI without a cable in it,it should operate through the whole range of clicks/changes effortlessly.Flooding a sticky STI usually sorts it,but make sure you don't get any grease or oil on the rubber hoods,it'll destroy them.

[rjb]

Had a similar experience with my daughters sora equipped bike. The cable was very taugh after the up shift from middle to big. The downshift then became increasingly stiff. Like you found i could only release the downshift lever after pulling the upshift tighter. The simple cure was to back of the cable tension a couple of stops on the adjuster.

[fatboy]

It sounds to me that the FD is hard against the H stop.................

It's the downshift ie;big to middle shift,that's giving the problem,if the mech is hard up again the H stop it'll release away from it.

I may be wrong but I had that issue when changing BB and hence chain line when I hadn't moved the H stop enough. Since you've got much more leverage with the swipe it's easy to push hard against the end stop enough to click the ratchet but without enough slack to allow easy release.

If the cable were sticky I think that the click would go OK but the FD wouldn't move. Still good advise to check for broken strands but I'm not sure it's the cause of the OPs problem

[reohn2]

I get the picture,and stand corrected if I'm wrong.
I've never experienced that problem

[Vitara]

Thanks for replies. It does seem that the problem is to do with tension and perhaps the H limiter. The inner cable has been replaced and although I stupidly didn't check the movement of parts while the cable was out (it was my first cable change) everything is moving fine in the other changes, it's just large ring down to middle that has a problem.

The way the shifters seem to work is that moving the lever across tensions the cable and a ratchet mechanism holds the cable in place. Pushing the button releases the ratchet one notch per click. So on the outer ring the cable is at its tightest and it seems to me that if its too tight it makes the ratchet hard to release with the limited leverage available from the small thumb button. If I push the lever across about 2/3rds of its travel, the thumb lever becomes easier to move and can be released, I presume this to be because I've taken some of the tension off of the ratchet mechanism.

I've tried setting the cable with less tension, but too little and it doesn't change gear at all and enough to get the mech moving and the problem is there.

I've also tried adjusting the H limiter. The H & L limiters are not marked but I've worked out by elimination that L is the inner screw and H is the outer screw. On the inner ring adjusting the L screw clearly moves the mech R & L respectively. Adjusting the H screw on the outer ring does not seem to illicit the same sort of movement – is this a clue?

I've also set the barrel adjuster on the cable in roughly the middle position to allow adjustment either way.

[CREPELLO]

I've also tried adjusting the H limiter. The H & L limiters are not marked but I've worked out by elimination that L is the inner screw and H is the outer screw. On the inner ring adjusting the L screw clearly moves the mech R & L respectively. Adjusting the H screw on the outer ring does not seem to illicit the same sort of movement – is this a clue?

I've also set the barrel adjuster on the cable in roughly the middle position to allow adjustment either way.

It could be. Have you undone the H screw completely? With it wound out, shifting from middle to outer ring should result in some over-shift being observed, once you pass the click for the outer position. It's always good practise to adjust the screw for a little movement past the outer ring position, but not so much that it results in the chain being unshipped.

If little or no overshift is adjusted for, then I think you could be experiencing the effect of that. If the pawl inside the STI mechanism doesn't settle properly into the teeth of the index disc, then the release mechansim (the button) won't work. I've found this from using Campag ergo shifters, which may be similar inside to Sora (thumb button) shifters.

Even if the H screw is properly adjusted, the STI mechanism could still be suspect - the clicks heard when shifting become quieter in STI's that have dried up grease. In which case, drenching it with lube will probably do the trick .