fastk9dad

I can't seem to figure this out. I'm running FSA Gossamer cranks, 105 triple FD and shifter. When I'm in the big chain ring and goto shift into the middle ring (2 clicks, 1st trim and then the shift) if I don't hit it just right sometimes it will drop completely into the small ring. It's not as if the FD is mis-adjusted as all the slack comes out of the cable, the FD is sitting on the low stop and the shifter is at the small ring position. Thinking it's a cable tension issue (too much), if I take tension off the cable to the point where shifting from small to middle is poor, it going from big to middle still exhibits the same issue.

I have adjusted the FD several times over according to the following, most notably steps 4 & 5: https://bike.shimano.com/media/techdo...9830702119.pdf

- Clearance in the middle ring trim position is set with cable tension.
- Big ring trim moves appropriately.


This has progressively gotten worse over time. New cables haven't helped. I'm beginning to think this may be a shifter issue with it passing by the middle ring position for some reason. Possibly worn or gummed up?

Any suggestions, besides getting a compact double?

Andrew R Stewart 

When the problem occurs where does the shifter spool end up? In the low position? Have you disconnected the cable from the der and by pulling the cable with your hand duplicated the problem shift? if so can you feel the shifter spool rotating too far? How old are the shifters? Model #?

Sure sounds like a shifter internal issue. Perhaps the ratchet isn't catching on what is the middle ring's steps (on the gear ring/spool). Andy.

JerrySTL

Have you tried cleaning all the gunk off the cable guide under the bottom bracket then lubing it?

cale

You will probably get better shifting by "cleaning things up" (and I don't mean squirting the buhoozafitz out of it with WD40) but I think it will only be very temporary. I'm going to guess these shifters have lived a hard/long life and have just worn out. If this is the case, it's replacement time.

fastk9dad

Funny you should mention that. I did exactly that this morning, let it sit, actuated the levers a few times, wiped it clean and then took it for a short test ride. Shifting was improved, only time will tell if it stays that way.

Shifters are 3 years old, ST-5703 is the model. The spool ends up in the low position. I didn't try duplicating it by hand with the cable disconnected.


No gunk on the cable guide but did put a drop of oil in the track when I came back from the test ride.

Al1943

Perhaps you need a better understanding of how Shimano road triple shifters work. There are 4 "main positions" for the 3 chainrings, plus an extra trim position for the smallest chainring. When shifting from the smallest chainring to the middle chainring this normally requires one good shove of the brake lever, from the first position to the THIRD position. The 2nd and 3rd positions are used for trimming the chain when running on the middle chainring depending on the position of the chain on the cassette (rear). The 4th position is for the big chainring and may be used to trim the derailleur if the chain is running on the largest cassette cogs (cross-chaining, not recommended). This design allows two trim positions for each of the 3 chainrings.

As you said in post #1 your problem does sound like you have too much cable tension, and possible too much friction in the shifter caused by dirt and old dry grease. WD40 shot into the shifter may help. You can also try lubricating the derailleur hinge pins. Of course new cables and cable housing may also help.

fastk9dad

I understand how the triples work and their 2 trim positions for each chainrings - what does that have to do with my pressing the lever in the big ring and it dropping all the way the way to position 1?

MikeWMass

If you have tried this then excuse me, but I have a 5703 as well and it sounds like you need to take up a quarter turn or two on the barrel adjuster for the front derailleur. The other thing I have found to help is to let the shift lever out slowly rather than just letting go. I have been very happy with my 5703, and once I got it adjusted it shifts better than my compact double ever did.

Al1943

Read my paragraph 2 post #6 . I agreed with you, too much cable tension. This condition requires more pressure on the small shift lever to make the cable release, and when it does release the elastic rebound pops the derailleur all the way over to the small ring position. Shifting from small to middle normally requires shoving the brake lever all the way to the right. I think turning the cable adjuster clockwise 1/2 turn more or less should take care of at least part of the problems.

Kimmo 

Maybe try backing off the high limit screw a tad, or reducing cable tension a smidge; if the cable's too tight when in the big ring, that could conceivably cause your issue, not to mention give the shifter a hard time.

fastk9dad

Ahh, I didn't see that when I replied. I do stay on top of my derailleur lube, but the WD40 did seem to help a lot. The shifter got a work out today on a very hilly course, in the rain no less and other than maybe 5 times it always shifted correctly from big to little.

The shifter is certainly touchy when it comes to shifting. Since the WD40 bath, I think most of my issue right now is how far I push the lever. If I go just a little too far it's going to the small ring.

fastk9dad

I did try backing out the high limit screw, didn't seem to have much affect on anything. Things seem better now so I'm going to ride it some more and will revisit cable tension if necessary.