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Downshift trouble with DA 7700 STI(6 posts)

Downshift trouble with DA 7700 STIgearhead
Aug 11, 2001 5:27 AM
I'm having difficulty downshifting the RD on my DA STI shifter. Seems like I often have to "prime" the inner lever a couple of times before I can convince it to drop down. I've tinkered with the cable, the barrel adjusters and the RD. It seems to have helped to use the frame screw on the RD to increase RD spring tension, and I re-greased the cable and housing but it's still not great. Any suggestions?
re: Downshift trouble with DA 7700 STIDrD
Aug 11, 2001 9:02 AM
Is the shifter ratchet mechanism not working (i.e., does the cable not release when you click the shifter?), or is the cable sticking (maybe binding under the bottom bracket?) or maybe the chain sticking on the cassette (if the cassette is worn?) or is the rear der. possibly bent or the der. hanger bent? (is the der. parallel with the cogs?) Lots of stuff to check!

If it's the shifter, the DA shifters can be taken apart a bit and regreased, which might help.
re: Downshift trouble with DA 7700 STIHank
Aug 11, 2001 11:22 AM
depending on the age of the cable and housing, they might just need to be replaced (they do wear out). Also, I don't recommend using grease on der. cables -- too heavy, too much friction. Use a very light oil like ProLink or Tri Flow or something. Anyway, that's what I'd try first. Also, of course inspect the rear der and der hanger for damage and maybe flush the STI shifter (I think Shimano recommends WD40 for this, but you should double check on that). Good luck.
Thanks for the ideas... but I thinkgearhead
Aug 12, 2001 9:35 AM
there's something wrong with the rear shifter: It releases cable and therefore downshifts fine when I hold the big lever in place when its in the workstand. But of course when you're riding you're just flicking it with your middle finger and there's no way to keep the big one from moving with it. Is there something wrong with the ratchet mechanism or is there an adjustment somewhere I'm missing?
That sounds to me like a fairly common problem with STIsSpoke Wrench
Aug 13, 2001 5:54 AM
I'd try hitting the inner workings of your lever with a little Tri-Flow and then cycle the shifter a few times. That usually does it. If I'm in the shop I usually give it a hit of compressed air to blow out the excess.
Replace the cable and housinggrzy mnky
Aug 13, 2001 9:40 AM
All of it including the section under the bar tape. Sounds like the friction in your systeme is too high. Eventually you get enough crap in the housing to really slow things down. Putting lube inside helps a t first but after a while it just makes a nice dirt slurry.