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And yet more shifter follies...

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And yet more shifter follies...

Old 05-26-14, 09:34 PM
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DIMcyclist
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And yet more shifter follies...

I've posted recently about some STI shifter problems; I'm revamping a few different bikes and each one has its issues:

the "moderately used" DA 7700 shifters I'd picked up for my sport bike turned out to have a few too many miles on them (returned for a refund; Ultegra shifters reinstalled, but not fine-tuned; the new cables are still stretching out)...

the 6400 STI shifters I'd planned on reusing on my RB-2 turned out to be rare; so, that rebuild is stalled until I decide whether or not to reuse them on another bike or sell them separately...

... and now the brand-spankin' new 'Claris' front (triple) shifter that I got to replace the dying 'Sora' on my Soma all-rounder is behaving strangely right out of the box. Strange like, in eight years of doing all of my own work I've never seen anything quite like it- it shifts up beautifully, but won't- exactly- shift back down to the granny-ring: at a single 'click,' it rockets through ALL of its down-shift index stops, yet won't actually release the cable- it stays taut, and won't release until it's de-tensioned at the F Der. nut. I've seen weak springs before, but this is unique; it's almost like it works a little too well.

My first thought was that the cable must be binding or jamming on something inside the shift mech, but if I simply hold & operate the shifter in one hand while tensioning the cable with the other, it shifts through its stops perfectly. While that seems hopeful, once the bike, when the cable is actually taut enough to shift up correctly, it won't shift back down- it just jams again.

I've checked the routing; it's properly seated in the shifter, and correctly routed to the FD. I've checked the cable; it's Shimano 1.2 mm stainless derailleur cable (so it's the right size).

Have any of you ever encountered anything like this? Does this indicate a defective shifter?

It's been driving me nuts for five days and I'm about ready to start pounding my head against the wall...

Last edited by DIMcyclist; 05-26-14 at 09:59 PM. Reason: Added the emoticon... for "fun."
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