Ultegra 6600 10sp STI Sticky shift?

KeepTriin
KeepTriin Posts: 6
edited May 2011 in Workshop
Hi,

I've got a Shimano Ultegra 6600 10spd setup with STI shifters. I've got a 12-25 cassette and the low-ratio (25 tooth) selection is fine. Shifting is all ok going down the block until I get to the 13 sprocket. Going back up is ok.

It looks like the cable tension at the high end (12 tooth) of the block is not sufficient to allow shifting. It seems like the cable sticks somewhere and then the STI lever just moves freely without engaging the shift. I can pull the cable where it's visible next to the downtube, and this will free the cable and allow the shift.

I first noticed this sometime ago and changed the cables (inner and outer) but the problem remains. Has anyone else experienced this? Any other ideas?

Cable is routed externally - doesn't have any "serious" radii...

It's frustrating to say the least.

Thanks in advance

Comments

  • ChrisSA
    ChrisSA Posts: 455
    H limit?
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  • KeepTriin
    KeepTriin Posts: 6
    Nope. Not the H limit - It will shift - eventually. It seems to be that the cable is getting stuck in the shifter ratchetting mechanism somehow, If I pull the cable next to the down tube it'll free off. Sometimes I'll hear a click in the STI shifter, then it'll shift.

    I've changed the outer cable housing to the rear mech - again. and after re-indexing and tensioning the cable, so far so good... It seems to be a fine balancing act of getting the cable tension attuned to the rear-mech?!

    Perhaps swapping the whole lot for SRAM might be a better move.
  • desweller
    desweller Posts: 5,175
    Have you tried running some oil into the shifter? There are moving parts in there...they need lubricating just like everything else.
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