Worn 105 STI

[hatler]

I have 105 shifters on the main bike, 2008 vintage (with the clothes line appearing from the side of the body).

On the RHS the upshift jumps from 4 to 6. Clicking back one gets me safely to 5.

I'm guessing the thing is simply worn a bit (over 30,000 miles on it).

Is it worth fixing ?  Is it a fiddly repair ?  (Is it even fixable ?)

[robgul]

From experience I wouldn't bother trying to fix it* - what's more surprising, assuming it is, is that the LH is still working . . . they usually fail first with the rather greater load shifting bigger gaps.

* and yes it is very fiddly.   I assume you've looked at/replaced the cable in case there's some fraying just by the nipple?

[Feanor]

Are you certain the asymmetric shifting is actually due to wear in the STI shifter?

Usually, it's friction in the cabling, particularly around the rear loop at the mech.
I'd be highly inclined to replace the cabling ( inners and outers ) before condemning the expensive shifter.

Rear mechs can also develop hysteresis due to worn pivots in the parallelogram, over many years. But I've never encountered this myself.

[hatler]

The phenomenon has persisted through at least a couple of complete cable (inner and outer) changes.

Worn pivots is a possibility, but the specific nature of the 'failure' leads me to believe it's a worn pawl.

[hatler]

It's a triple, so the LH doesn't see too much action, which might explain why that's still working perfectly.

I had figured that a disassembly and repair of the gizzards of the shifter would likely be too pingfuckit strewn, so have prepared for its eventual demise with a couple of spare sets of triple shifters.

But if it was a straightforward fix, I'd be up for that if it got any worse.

[Jurek]

I have totally dismantled and re-assembled a Sora STI.
My advice would be don't. There is a reason that Shimano only provide an exploded view diagram for the most basic of disassembly.
I seem to recall it took something like 80 hours and around 30 attempts to re-assemble it - including having to fabricate some spring retainers to facilitate the process.
I managed it successfully, in the end.

[hatler]

Bloody hell. Useful as an intellectual exercise when there's nothing better to do I would imagine. Thanks for that nugget.

I think I'll live with it until I can't, and then use up one of my spare shifters.

[JonBuoy]

If it was mine I would give the innards a good blasting out with WD40 or similar.

[LittleWheelsandBig]

Have you tried relubricating the innards? The grease can get sticky.

[hatler]

Hmm. Good thinking. Thank you. I'll give that a go.

[Jurek]

Bloody hell. Useful as an intellectual exercise when there's nothing better to do I would imagine. Thanks for that nugget.

I think I'll live with it until I can't, and then use up one of my spare shifters.

I had little choice.
Money was tight at the time, and I needed to get the bike into working order.

[sojournermike]

I have totally dismantled and re-assembled a Sora STI.
My advice would be don't. There is a reason that Shimano only provide an exploded view diagram for the most basic of disassembly.
I seem to recall it took something like 80 hours and around 30 attempts to re-assemble it - including having to fabricate some spring retainers to facilitate the process.
I managed it successfully, in the end.

Chapeau!!

[sojournermike]

I have 105 shifters on the main bike, 2008 vintage (with the clothes line appearing from the side of the body).

On the RHS the upshift jumps from 4 to 6. Clicking back one gets me safely to 5.

I'm guessing the thing is simply worn a bit (over 30,000 miles on it).

Is it worth fixing ?  Is it a fiddly repair ?  (Is it even fixable ?)

Off topic, but this made me think - I use two cameras that are over 50 years old and both work perfectly. Yep, they use film but I can still get them repaired if they ever need it. I could buy an expensive and amazing digital equivalent, but I think it unlikely it will be working and still less repairable in 50 years. There’s something to be said for ‘simpler’ stuff.

[Jurek]

I have totally dismantled and re-assembled a Sora STI.
My advice would be don't. There is a reason that Shimano only provide an exploded view diagram for the most basic of disassembly.
I seem to recall it took something like 80 hours and around 30 attempts to re-assemble it - including having to fabricate some spring retainers to facilitate the process.
I managed it successfully, in the end.

Chapeau!!

I Thankyouw!

[LittleWheelsandBig]

I have rebuilt a few 8sp STI but not more recently. It was tricky and often futile. The 8sp Ultegra levers tended to break the same internal piece and the only spares were from scrapped levers.

[Lightning Phil]

I got sick of my STI levers breaking and changed to bar end levers.