Dura Ace 7800 shifting problems - HELP!
Hello and good to be back - haven't posted here for years but I'm stuck and I know this is where the experts live!
I have a Dura-Ace 7800 Triple setup on the Ti Kinesis road bike and recently the shifting has gone right downhill. Setup is 52/42/30 triple with 13-28 on rear and Dura-Ace 7800 long cage mech. Symptoms are inability to perfectly index around middle of block mainly when in 52 ring. You can adjust so that it will index up the block nicely but then it wont drop down the block but will delay or just not drop down at all. Groupset is obviously at least 5 years old but is in good condition. I have checked all the obvious things and recently changed cassette, chain (correct length) and cables (inners and outers). Frame is new (groupset came from older bike) and dropout is straight. Outer cable at rear mech is not too short and not binding
I have changed cables a few time to no avail and experimented with shorter chain also to no avail. It "looks" like the rear mech spring doesn't have the oomph to snap back when going down the block but this is the second mech I have tried (although this one wasn't new but very good second hand and looks behave identical to previous). I have two rear mechs and issue is identical with both of them.
The only thing I haven't looked at is the shifters but these appear to be working completely normally, operation seems smooth and snappy as expected
Any ideas please? This one really has me stumped
I have a Dura-Ace 7800 Triple setup on the Ti Kinesis road bike and recently the shifting has gone right downhill. Setup is 52/42/30 triple with 13-28 on rear and Dura-Ace 7800 long cage mech. Symptoms are inability to perfectly index around middle of block mainly when in 52 ring. You can adjust so that it will index up the block nicely but then it wont drop down the block but will delay or just not drop down at all. Groupset is obviously at least 5 years old but is in good condition. I have checked all the obvious things and recently changed cassette, chain (correct length) and cables (inners and outers). Frame is new (groupset came from older bike) and dropout is straight. Outer cable at rear mech is not too short and not binding
I have changed cables a few time to no avail and experimented with shorter chain also to no avail. It "looks" like the rear mech spring doesn't have the oomph to snap back when going down the block but this is the second mech I have tried (although this one wasn't new but very good second hand and looks behave identical to previous). I have two rear mechs and issue is identical with both of them.
The only thing I haven't looked at is the shifters but these appear to be working completely normally, operation seems smooth and snappy as expected
Any ideas please? This one really has me stumped
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Comments
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Hmm. sounds frustrating.
IME of trying to achieve perfect indexing at the rear, even with all new drivetrain parts, you can have it shifting perfectly one moment with a particular chain/cassette then switching cassettes (even to another new one) and the tell tale rattling appears in certain ratios (usually in the larger sprockets) for no explicable reason. Maybe some tiny machining differences in the cassette teeth are responsible.
Take it you have started from scratch numerous times with the new setup, i.e. backed off the barrel adjuster, loosened the rear mech cable pinchbolt and started all over again?0
