Shifter maintenance Shimano ST-1055" (8sp-1989+) shifter (STI).

[Andy in Germany]

We've received a donation of a rather nice centurion racing bike. Unfortunately the shifters are not working; they won't shift up or down, and they're apparently jammed in the lower gear so we can't get the cable out.

Is there a way to dismantle these shifters so we can loosen the ratchet and pawl? I have a trainee looking through YouTube videos but so far without success.

Also, I'm guessing the screw in the front centre is for access to the brake cable, is that correct?

 

[Chislenko]

I don't know about dismantling, not something I would undertake. I had a similar problem with an old Sora one. I simply looked where the nipple was, drilled a small hole in the casing (very soft metal) and took the nipple out through the hole.

A small grommet from my never ending box of assorted grommets plugged the hole and no-one is any the wiser as the hood covers it.

 

[Andy in Germany]

Fair enough.

We have a set of apparently working 105's but they're 9 spd. If I change from 8spd to 9spd I know the cassette and chain need swapping, and I'm guessing the Freehub. What else would need to be changed?#

Also, how specialised are these parts? I'm guessing a 9spd mtb cassette won't work...

 

[EckyH]

@Andy in Germany Probably you already know the sheet but if not: the exploded views of Shimano parts are really helpful for me.
Here is the one for the ST-1055 STI: https://si.shimano.com/en/pdfs/ev/ST-1055-1321/EV-ST-1055-1321B.pdf

E.

 

[Drago]

The original grease hardens with age and become wlmost likemfine concrete and can lock STi's into whatever gear they were left parked up in.

Its worth dosing them internally with WD40 (other similar sprays are available) a couple of times a day, and after a few days gently wiggling them and continuing the spray. Quite often they will free up nicely.

 

[Dogtrousers]

I did this to a modern 105 shifter - jammed the cable. I spent ages faffing around with needle nosed pliers and squirting WD40 and the like into it. All to no avail. Took it to my LBS and they used secret magical skills to fix it.

 

[Ajax Bay]

Andy - hi
Freehub for an 8sp will take a 9sp cassette without spacers and a 10sp with a 1mm spacer.
Echoing advice above, I'd be wary of any dismantling as a first step, and steep it in WD40/GT85 through every orifice.
Forgive if tygtse but important to have tension on the cable (by hand) when trying to click 'down' the (virtual) cassette,
Ref 'bolt': isn't access to the brake cable (ie to replace) just in over the top with the lever applied?
Consider adding the model number to your title so those that come after know this thread is about a "Shimano ST-1055" (8sp-1989+) shifter (STI).

 

[T4tomo]

I did this to a modern 105 shifter - jammed the cable. I spent ages faffing around with needle nosed pliers and squirting WD40 and the like into it. All to no avail. Took it to my LBS and they used secret magical skills to fix it.

I successfully unjammed a 10spd Tiagra shifter - the culprit was frayed cable and took patience and tweezers a pointy thing and gravity.
I would echo the advice of not trying to dismantle beyond removal of hood or access covers.
I would also echo dousing the feck out them with GT85 or WD40 or similar.

That old "washing line" style shifter was less prone to chewing cables than the more modern "rear exit to run under bar cable" style so hopefully just solid grease and crud.