|Ghost Shifting||HENRY K|
Apr 13, 2003 5:09 AM
|I have a problem while climbing/standing with the chain jumping in the rear (Ultegra 9-speed). It was diagnosed (correctly from what I can see) as ghost shifting. Everything shifts just fine while seated until I really start cranking out of the saddle (only in the middle cogs, not the first 2 or 3). There does not seem to be any hang-ups or irregular friction with the shift cable anywhere. Also, it appears to be a fairly recent problem so I don't think that excessive frame flex would be the cause since I have had the bike for 2 years. ANY SUGGESTIONS?|
|re: Ghost Shifting||Juanmoretime|
Apr 13, 2003 6:51 AM
|Henry, sometimes being off on your rear derailleur ajustment by a 1/4 to 1/2 turn will have it shift just fine and skip when your really putting the pressure on. Also how many miles on the cassette? It also could be worn out if there are a lot of miles on this cassette and you send a lot of time in the cogs that your bike is skipping on. Is it skipping or trying to jump up or down the cassette? If it's trying to go down adjust it a 1/4 turn out ride and if it keeps skipping keep trying 1/4 turn adjustments. Do the opposite if it's trying to jump up the cassette.|
|Per Sheldon Brown Cable guide under the bottom bracket
Apr 13, 2003 9:40 AM
|It may be that the cable guide under the BB is gummed up. When you flex the frame, the overall path for the rear derailleur cable is made a little longer. This should not normally be a problem. But if the cable guide will not let it go back, each flex will ratchet it a little tighter until it is enough to try to shift.
You can go to his site for a better explanation.
The cable could also be sticking at other places.
|I'm betting on a worn cassette and/or chain.||Spoke Wrench|
Apr 13, 2003 4:52 PM
|I'd think that if the shift cable were hanging up, it'd do it all of the time, not just when you're honking. I'd think the same would be true if the derailleur was a scosh out of adjustment. Actually, derailleurs usually shift better when you let up a bit as you're shifting.
If those are the cogs that you use the most, I'd definitely treat your bike to a new cassette and chain.
|re: Ghost Shifting||mackgoo|
Apr 13, 2003 6:11 PM
|Did you by chance change the chain? This happened to me last year, Record 10sp. I changed the chain and it would jump sprockets when I put alot presuure on the cog I most commonly ride. No adjustment fixed it. After about 100 miles everything bedded in and now all is well.|
|re: Ghost Shifting||S-U-B|
Apr 14, 2003 9:07 PM
|if you figure it out post it here, I'm having the exact same problem. I just together a new bike with the components off an old bike (ultegra). I have four different cassettes for 3 bikes. The bike shop told me it was because I replaced my chain and I need to replace my cassettes which did not make since to me because I put a brand new chain on my other bike at the exact same time and I use the exact same wheels and cassettes and I do not have the same problem on the other bike. It is tough to fix because when you have it on the stand it shifts fine, then When I'm in a crit sprinting for the win, it starts jumping all over the place which makes it kinda tough. I would start with the adjustment of the derailer, that is the route I have taken and I seem to almost have it straightened out. If you find something else to be the cause let us know.|| |