Yes, others are right in that cable tension is key with indexing, especially as the number of rear cogs increase. Barrel adjusters are your friend. From your description, i would say that you probably have just slightly too much tension--maybe a 1/2 or 3/4 turn of the barrel adjuster in might help.
I usually setup indexing by adjust limit screws first, then set the cable anchor, just barely taking up all cable slack in the smallest cog. Then i shift into the second to smallest cog--just one jump--and check to make sure that that derailleur pulleys are centered under that cog. If not, i use the barrel adjuster to fine tune it's position. Then I shift up into the higher parts of the cassette and double check. As long as the derailleur is staying centered in each gear you should be getting even shifts up and down. If the derailleur is centering well, especially on the way up, but hanging up going down, another culprit might be friction in the cable housing, which I imagine might be a problem with the long cable runs on a tandem. The shifter is shifting but friction in the system is holding the cable against the spring in the derailleur. If that's the case, try lubricating the cable housing and any cable guides with a thin lubricant like TriFlow. Finally, if you're getting even shifting in one part of the cassette but not in another, your derailleur hanger might be slightly bent. Any good LBS should have the Park hanger alignment gauge, which checks to make sure that hanger threads are perpendicular to the plane of the wheel (and thus the cogs). With most frames, especially steel ones, you can also use the gauge to slightly cold-set the hanger into proper alignment, although if it's a badly bent replaceable aluminum hanger cold-setting in back might crack it. On Saturday, July 13, 2013 11:23:33 AM UTC-7, Michael Hechmer wrote: > > I stopped using indexed shifting about ten years ago, and reverted to > friction, which seemed to require less fussing, at least in the shimano > version. Now I have a tandem with shimano BE's, which was set up by a bike > shop. Perhaps one of you who works with this stuff regularly can offer some > guidance. > > The rear shifting worked quite well but it took me 2 1/2 years to get the > front end shifting predictably (for those of you who have never ridden a > tandem, front end shifting is a very different animal). While fixing the > front end, which now works perfectly, I replaced the much too big Deore XT > RD with an Ultegra 6700 GS, and can't seem to get it to work quite right. > The limit screws are good, as is the B screw, and the cable tension feels > quite high. The indexed shifter lifts the chain fine from the outside all > the way up to the inside (28) cog; but when I start down it will hang up > between the 1 & 2 position, then jump two cogs on the next click; it then > hangs between 7 & 6, and jumps 2 cogs to 5. After that it is OK, except > for that indexing hesitation which I hate. The chain (wipperman 908) has > just a few hundred miles on it and the cassette (11-28 HG) is new. > > Right now, I have reverted to friction which seems to be working fine, but > would like to get the dang index to behave! > > Michael > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/groups/opt_out.
