D/A STi poor shifting??

dieselgeezer
Posts: 231
Hi,
I'm sure this has been done to death but thought I'd try again to get some answers.
D/A 7800 STi's of 2007 vintage on the best bike so have done about 20000 miles. This year in particular the rear shifting has been appalling. I consider myself a fairly useful mechanic but this one has me stumped. I've substituted rear mech, cassette, new chain, new cables but all to no avail. If I change the cable tension to get the changes in one direction correct then it won't shift back properly the other way, & vice versa. Have checked hanger alignment & tried alternative B screw positions but again had no effect. I'm convinced it's the ratchet mechanism within the lever but thought it would have lasted longer than it has.
Am I missing something fundamental?
Please no "change to Sram or Campag" suggestions.
Many thanks
I'm sure this has been done to death but thought I'd try again to get some answers.
D/A 7800 STi's of 2007 vintage on the best bike so have done about 20000 miles. This year in particular the rear shifting has been appalling. I consider myself a fairly useful mechanic but this one has me stumped. I've substituted rear mech, cassette, new chain, new cables but all to no avail. If I change the cable tension to get the changes in one direction correct then it won't shift back properly the other way, & vice versa. Have checked hanger alignment & tried alternative B screw positions but again had no effect. I'm convinced it's the ratchet mechanism within the lever but thought it would have lasted longer than it has.
Am I missing something fundamental?
Please no "change to Sram or Campag" suggestions.
Many thanks
-- "I am but a spoke in the wheel of life" -- Ghandi
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Comments
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Usually a sign of cables sticking. When you changed cables did you also change the outers, especially the last bit that goes into the derailler? Typically gets grotty inside and cable just 'sticks' leading to ok shifts in one direction only.
Have you also sprayed a bit of PTFE inside the STI's. Sometimes the innards get a little gunked up or rusty (i overtightened the face plate on mine once and found it prevented the internal ratcheting system from turning properly)?0 -
Agree on cables and installation. Cutting the ends clean and square (use a bench grinder) and open out the liner with a sharp point. Don't wrap the tape too tight also.Make mine an Italian, with Campagnolo on the side..0
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I sprayed lube inside the shifter to no avail. Will fit another new set of inner & outer & see if it makes any difference.
Monty, just wondering what you mean by "don't wrap the tape too tight". Are you thinking 7900? (these are 7800).
Many thanks-- "I am but a spoke in the wheel of life" -- Ghandi0 -
Another thing worth thinking about is how the cable attaches to the rear derailler. These days, direct pull systems are the way to go in order to prevent problems like this. If your derailler has a big loop of outer cable going from the end of the frame to the rear of the derailler you might want to try converting it to direct pull with an Avid Rolllermajig.0
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Problem now solved, in a way. Borrowed an Ultegra rear shifter, fitted & adjusted & it works, albeit typically fiddly Shimano to get just right. So, my D/A expensive levers have lasted 20k miles. I've had far more life out of Tiagra.
Thanks for your input & suggestions though. Much appreciated.-- "I am but a spoke in the wheel of life" -- Ghandi0 -
Have you ever had a frayed cable in the shifter? There might be a loose strand still in there.- - - - - - - - - -
On Strava.{/url}0 -
DesWeller wrote:Have you ever had a frayed cable in the shifter? There might be a loose strand still in there.
Good call. You need to periodically check that the cable is not fraying inside the shifter. The cable curves over the mechanism and is prone to fraying... this will result in poor shifting, chain skipping sprockets etc. Eventually the cable will break completely and bits of the cable will wrap themselves inside the mechanism and then it's likely to be impossible to fix (i know cos it happpened to me, lbs told me they had seen this problem many times with the 7800 DA STi's).0 -
Never had a cable fray or break & there are no bits in there. Thinking back, this issue started at the begining of 2011 so the lever lasted closer to 15k than 20k.-- "I am but a spoke in the wheel of life" -- Ghandi0