Shimano Tiagra STI RH shifter not working after cable snapped

Twilkes

Guru
My right hand shifter always shifted up the sprockets fine (i.e. up to the largest sprocket, pushing the whole lever with my fingers) but on the last few rides I noticed it didn't always make it down to the smallest cog when clicking with my finger. I thought it was just derailleur alignment, but the last ride it struggled to get down even to the last two or three sprockets.

Halfway through that ride I was shifting up a few clicks at a time when the cable snapped in the shifter, so thought it must have been a damaged cable that was preventing the proper downshift. So new inner and outer, no problem.

But the shifter isn't working - I can't push the whole lever any further, there is resistance as if it's in the 'largest sprocket' position, and nothing is happening when I push the little downshift lever; it moves but there is no click. It's the same whether there is no cable fitted or whether the new cable is fitted and under tension.

It's been around or below 0°C for over a week, so could it just be that the mechanism froze up and it can be loosened with GT85 or something like that? The brake function of the lever also felt stiff at the start of the ride but loosened up after a few minutes. Is it worth taking it apart a little to see if there is anything obvious?

How will I find out if the mechanism is broken and it needs replacing? New shifter looks like £90. :-/
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Bring the bike in the house then check again. You could have cable fragments stuck. You've already changed inners and outers.
 
OP
Twilkes

Twilkes

Guru
Bring the bike in the house then check again. You could have cable fragments stuck. You've already changed inners and outers.
Will have a look. How should a shifter with no cable in it behave, should it still shift up and down its positions even though there's no cable tension?
 

Big John

Guru
Warm it up, like fossyant says, and spray a shed load of GT85 in the mechanism. If that doesn't work then try and find a bike shop with an ultrasonic digital cleaner. We've got one at work. It's like a small deep fat fryer which cleans parts with the aid of ultrasound. We put an STI lever in that had stopped working, like yours by the sounds of it. After a 30 minute wash we took it out, dried it and surprisingly it worked, all clicks up and down. And it was spotless lol. There are YouTube videos that show you how to partly disassemble a lever but there comes a point where if you go any further you run the risk of never getting it back together again. I'd definitely try the easy options first i.e. GT85 at room temperature.
 
OP
Twilkes

Twilkes

Guru
Will bring it into the warm and check. The brake lever is still sticking occasionally, doesn't feel like the brake caliper itself, so that might also indicate something stuck in the shifter.
 
OP
Twilkes

Twilkes

Guru
It's a Tiagra 4700 shifter - is there any simple disassembly I can do to get access to some of the innards without ending up with springs and ratchets all over the floor?
 

Gunk

Veteran
Location
Oxford
If you can see the frayed end of the cable when the lever is pulled open, pull the end of the broken cable with a pair of pliers whilst downshifting, that will unwrap it from the mechanism, you should then be able to remove the broken cable
 
OP
Twilkes

Twilkes

Guru
If you can see the frayed end of the cable when the lever is pulled open, pull the end of the broken cable with a pair of pliers whilst downshifting, that will unwrap it from the mechanism, you should then be able to remove the broken cable
The mechanism won't shift in any direction, that's the problem, if I could take the case off to have a look that might make it easier to see what's going on. I can't see anything stuck in there and a random wiggle around with the thin end of an Allen key achieved nothing.
 
OP
Twilkes

Twilkes

Guru
If you look for the Shimano dealer manual for the particular model, there may be a section explaining how to deal with this, at least there's for the Sora stis. Fixing involves some simple disassembly and a couple of interestingly shaped prodding tools.

Here it is for tiagra, final couple of pages https://si.shimano.com/pdfs/dm/DM-ST0002-05-ENG.pdf
Thanks, yeah no that's not for me, they lost me at 'E ring'. :smile:

Managed to get a cancellation slot at the LBS for tomorrow (next appointment otherwise was mid-March!) so will see what they can do, else will suck it up and fit a new shifter.
 
  • Like
Reactions: C R

Chislenko

Well-Known Member
Thanks, yeah no that's not for me, they lost me at 'E ring'. :smile:

Managed to get a cancellation slot at the LBS for tomorrow (next appointment otherwise was mid-March!) so will see what they can do, else will suck it up and fit a new shifter.
Have the same problem with a snapped off cable and was excited to see this user manual but like you was stopped in my tracks by the e-ring!!
 
Top Bottom