Author Topic: Shimano 105 STI triple shifter jammed  (Read 347 times)

Shimano 105 STI triple shifter jammed
« on: May 15, 2020, 05:56:26 pm »
I was just tweeking the gears to account for a bit of cable stretch following the tandem rebuild I posted about on here, and the left hand lever has jammed in the fully pulled position.  The inner lever has a slight detent towards the end of it's movement but does not release the cable.  I've tried releasing the tension on the cable but still no joy.  The outer (brake) lever has 10-15 deg free movement inwards and then is solid.

Is there a ratchet release that can be poked with a screwdriver or somesuch device or is the lever fcuked?

Help please,

R

Re: Shimano 105 STI triple shifter jammed
« Reply #1 on: May 15, 2020, 07:37:50 pm »
one of my chums had this exact problem and I advised him to try and fix it without taking the lever apart, on the basis that something had come adrift inside and it might be persuaded back in as easily. What I didn't expect to happen (or advise) was that tools were applied to the cable spool in order to force the mechanism backwards.   The lever appeared to work again after this but rather ominously there was a fragment of metal that came out and the cable nipple had a gouge in it.  After this the lever was tested and it didn't work properly.

I think what may have happened was that the cable had enough 'spring' that the  nipple popped out of its seating in the spool whilst the cable was slack, and then protruded far enough that it stopped the spool from rotating.  If the cable is allowed to go slack  when the shifter is set in any other position than the one that is used to change the cable, there is presumably  a danger that this might happen. [There is also a query in my mind about the exact nipple size and shape; some sizes/shapes may favour it popping out and not reseating itself.]

Anyway if this has happened you may be able to tease the nipple back into the spool, provided you can get access to it. I don't recommend doing what my chum did.

cheers

Re: Shimano 105 STI triple shifter jammed
« Reply #2 on: May 16, 2020, 09:50:44 am »
When replacing the inners, I find that on my 105 triple that there is usually fraying of the cable in the shifter near the barrel.

Could this have happened?


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robgul

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Re: Shimano 105 STI triple shifter jammed
« Reply #3 on: May 16, 2020, 10:25:36 am »
When replacing the inners, I find that on my 105 triple that there is usually fraying of the cable in the shifter near the barrel.

Could this have happened?


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Agreed - experience from my time at the LBS and it was invariably inner cables fraying that caused levers to jam - and most often on the LH lever where the stresses are greater with a bigger pull across the chainrings.    There was often quite a bit of digging with a pointed tool to extract the nipple and short bit of frayed cable.   IIRC 105 was a more frequent offender.

Rob

Re: Shimano 105 STI triple shifter jammed
« Reply #4 on: May 16, 2020, 10:50:14 am »
frayed cables are commonplace in RH shifters but much less so in LH shifters.

The happenstance I described occurred with a new cable in a shifter which had hitherto worked perfectly. The golden rule is never to allow a slack cable except when the shifter is in the 'cable change' position.

The current generation of STIs has a much deeper recess for the nipple to sit in (so it is less likely to pop out) and an access panel alongside the spool so that frayed /displaced cables can be dealt with. In this respect it is a much improved design.

cheers

Re: Shimano 105 STI triple shifter jammed
« Reply #5 on: May 16, 2020, 11:08:58 am »
Thanks for the replies.  I can report that all is now well.  I peeled back the hood and could see the nipple in its hole.  We have S&S couplings so I disconnected the cable at its coupler and pushed the inner inwards and saw the nipple move out of its seat.  Pulled the inner back in again and all worked! Relief all round.  For the record the shifter is a ST5703.

The golden rule is never to allow a slack cable except when the shifter is in the 'cable change' position.

As we have S&S couplings we will have a slack cable at times - what is a reliable method of making sure the shifter is in the 'cable change' position without peeling back the hood?

Re: Shimano 105 STI triple shifter jammed
« Reply #6 on: May 16, 2020, 01:02:59 pm »
Huzzah !!
Rust never sleeps

Re: Shimano 105 STI triple shifter jammed
« Reply #7 on: May 16, 2020, 01:17:08 pm »
I have fully dismantled a non-functioning LH Sora lever when funds precluded replacing it.
I did fix it in the end.
But it took an entire weekend, and I had to fabricate some tools in order to do so.
I think I must've re-assembled it about 30 times.
It isn't a course of action I would recommend.
I've never seen so many pingfuckits in one mechanism.

Re: Shimano 105 STI triple shifter jammed
« Reply #8 on: May 16, 2020, 04:08:45 pm »
Thanks for the replies.  I can report that all is now well.  I peeled back the hood and could see the nipple in its hole.  We have S&S couplings so I disconnected the cable at its coupler and pushed the inner inwards and saw the nipple move out of its seat.  Pulled the inner back in again and all worked! Relief all round.  For the record the shifter is a ST5703.

The golden rule is never to allow a slack cable except when the shifter is in the 'cable change' position.

As we have S&S couplings we will have a slack cable at times - what is a reliable method of making sure the shifter is in the 'cable change' position without peeling back the hood?

with a LH shifter it is presumably a question of shifting into the small chainring position (and RH into the small sprocket) before decoupling.  I'd also assume that there ought to be some cunning method of using something (O rings, elastic bands?) to make sure the cable doesn't become fully slack and the nipple remains in its seat. Finally I suppose it ought to be possible to use something like blu-tack to ensure that the nipple is unlikely to come out its  seat when it isn't meant to.

cheers