#1
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Powershift upshifting on its own if you hit a bump hard enough?
Just at the LBS and talking to one of the staff there that had 11 speed silver Centaur on his bike.
He said on more than one occasion, he'd hit a bump on the road hard enough that his drivetrain would end up going up a gear (smaller cog). He pointed the finger at the Powershift lever. I've ridden Powershift Athena 11 for a bit but have never had that happen to me. Never had it happen on my current Ultrashift either. Anyone here ever experience it themselves or hear about it? |
#2
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All slanted-parallelogram rear derailers are affected by bump forces, and unless the spring is stiff enough and the cable also straight and thus stiff enough, auto-shifting can occur in response to abrupt road defects.
But it's usually just momentary, and goes back to the same cog that the chain was on. Unless that is: 1) the shift lever actuated or slipped or 2) the cabling and/or adjustment was sufficiently poor for the gear selection to be less robust and thus allow a "choice of gears" within any indexed position of the shift lever, wherein the derailer might fail to return accurately and immediately to it chosen gear position (cable friction being a possible factor here). |
#3
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Haven't had it happen in ~4 years of riding Potenza on the main bike, which uses the same Power shift mechanism.
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#4
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It doesn’t seem like this should be a product specific, or even a brand specific problem. I experienced this only twice in the past four years. Once on a Campy 8sp drivetrain, and once on a SRAM Red setup. In both cases I concluded the cause to be cable stretch a few weeks after installation leading to the index position drifting off center and mysterious shifting at random times. Sometimes I didn’t even have to hit a bump!
In both cases checking and centering the indexing solved the problem. Cleaning the chain and gunk between cogs helps too. |
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