Front shifting problems
#1
Thread Starter
Senior Member
Joined: Apr 2006
Posts: 1,306
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From: Aurora, CO
Bikes: CAAD9-1, Windsor Cliff 29er
Front shifting problems
Okay, I bought a bike last year with Dura-Ace 7900 and I'm really frustrated with the shifting, mostly in the front. It's a compact crank and a wide 11-28 cassette. I have two problems. The big one is that on upshifts I notice that sometimes the chain goes up to the big chainring but the links are not seated properly in the chainring. They are riding up about half the chain height. I'm not sure how it's doing that, but it is. When the first part of the shift gets about at the 3 o'clock position the chain finally clanks into position.
On downshifts I experience sort of the opposite problem. It shifts down fine, and I think it settles okay in the chainrings, but when the part of the chain that first shifted down gets to also about 3 o'clock or a little bit lower the chain fully clicks into place and the bottom side rattles, or oscillates for a little while.
Any ideas what is going wrong or how to fix it? I've installed a new chain. I've tried following all the procedures for adjusting the derailleur. No luck so far. It almost seems to me the chainrings aren't aligned as they should be or something like that, in order for this to happen.
Unfortunately bikeforums/youtube combination kind of hosed up the videos by ending or starting too early in the transcoding process. If you go to the actual youtube links you can see the issue a little better. If it still doesn't make sense I'll update the videos. Thanks.
Upshift problem:
Downshift problem:
On downshifts I experience sort of the opposite problem. It shifts down fine, and I think it settles okay in the chainrings, but when the part of the chain that first shifted down gets to also about 3 o'clock or a little bit lower the chain fully clicks into place and the bottom side rattles, or oscillates for a little while.
Any ideas what is going wrong or how to fix it? I've installed a new chain. I've tried following all the procedures for adjusting the derailleur. No luck so far. It almost seems to me the chainrings aren't aligned as they should be or something like that, in order for this to happen.
Unfortunately bikeforums/youtube combination kind of hosed up the videos by ending or starting too early in the transcoding process. If you go to the actual youtube links you can see the issue a little better. If it still doesn't make sense I'll update the videos. Thanks.
Upshift problem:
Downshift problem:
#2
Senior Member
Joined: May 2011
Posts: 140
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This may be a long shot, as I've never had this problem so I haven't watched this closely, but in the second clip, it looks like the chain is flopping around excessively after the shift. This leads me to question whether the rear derailleur is properly taking up the excess slack or otherwise tensioning the chain properly. Perhaps this could also account for the problem in the first clip. How did you determine chain length? Is the chain properly lubed?
#3
Thread Starter
Senior Member
Joined: Apr 2006
Posts: 1,306
Likes: 0
From: Aurora, CO
Bikes: CAAD9-1, Windsor Cliff 29er
This may be a long shot, as I've never had this problem so I haven't watched this closely, but in the second clip, it looks like the chain is flopping around excessively after the shift. This leads me to question whether the rear derailleur is properly taking up the excess slack or otherwise tensioning the chain properly. Perhaps this could also account for the problem in the first clip. How did you determine chain length? Is the chain properly lubed?
#4
Is the chain a Dura-Ace chain? If it is alot of people don't know that Dura-Ace chains have a front and back side u will notice on the chain it says Dura-Ace on one side and not the other. Side with Dura-Ace faces out very important my chain was doing the same as yours. The 7900 chainring has special pickups on the teeth to help it move up to big chain ring. The Chain is kinda rounded on one side if u look at.
Here is Tech Doc on it
https://techdocs.shimano.com/media/te...9830682232.pdf
Drive-train compatibility- there is only 3 chains that work on 7900 https://bike.shimano.com/publish/cont...ty%20Chart.pdf
Here is Tech Doc on it
https://techdocs.shimano.com/media/te...9830682232.pdf
Drive-train compatibility- there is only 3 chains that work on 7900 https://bike.shimano.com/publish/cont...ty%20Chart.pdf
Last edited by PistaDalMine; 06-14-11 at 10:30 PM.
#5
Thread Starter
Senior Member
Joined: Apr 2006
Posts: 1,306
Likes: 0
From: Aurora, CO
Bikes: CAAD9-1, Windsor Cliff 29er
Is the chain a Dura-Ace chain? If it is alot of people don't know that Dura-Ace chains have a front and back side u will notice on the chain it says Dura-Ace on one side and not the other. Side with Dura-Ace faces out very important my chain was doing the same as yours. The 7900 chainring has special pickups on the teeth to help it move up to big chain ring. The Chain is kinda rounded on one side if u look at.
Here is Tech Doc on it
https://techdocs.shimano.com/media/te...9830682232.pdf
Here is Tech Doc on it
https://techdocs.shimano.com/media/te...9830682232.pdf
Since the bike is new I took it in for the tune-up a few weeks ago. Didn't seem like they even touched it. I might call the shop and complain and see if they can give it a closer look. I hate paying for bike mechanic work stuff though, I like to do most of it myself, which is why I asked here. I might take a closer picture of the issue tomorrow. I appreciate the ideas.
#6
Also when u check it tomorrow look at the rear derailleur hanger make sure its straight and not bent that will make a chain jumpy like that.
Make a another video with both the front and rear derailleurs in view of the camara and shift the front up and down like u did shift it 2 times on one video tho.
Make a another video with both the front and rear derailleurs in view of the camara and shift the front up and down like u did shift it 2 times on one video tho.
#7
Thread Starter
Senior Member
Joined: Apr 2006
Posts: 1,306
Likes: 0
From: Aurora, CO
Bikes: CAAD9-1, Windsor Cliff 29er
Also when u check it tomorrow look at the rear derailleur hanger make sure its straight and not bent that will make a chain jumpy like that.
Make a another video with both the front and rear derailleurs in view of the camara and shift the front up and down like u did shift it 2 times on one video tho.
Make a another video with both the front and rear derailleurs in view of the camara and shift the front up and down like u did shift it 2 times on one video tho.





