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:

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?

Thanks for the response. The chain is lubed fine, I don't think that's the issue. I used the big/big+2 links (1 inch) method for sizing the chain. But perhaps with a 28T cassette that's the problem. I'm more worried about the first clip though, how the chain doesn't seem to seat right away on the upshift. I looked closer and it's an extension of the spot right where the chain first grabs and half of it is below towards the lower chainring and the other half is hooked onto the big ring. Well, the links that follow on top from where it grabs on to the big chainring don't sit down in the grooves. Who knows, maybe just give it a few hundred miles and it will all settle in :-)

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
http://techdocs.shimano.com/media/te...9830682232.pdf

Drive-train compatibility- there is only 3 chains that work on 7900 http://bike.shimano.com/publish/cont...ty%20Chart.pdf

The bike came with a KMC chain. I only have a few hundred miles on the bike but I got around to measuring the chain at it was already at 12 1/8" for 12 links. So I replaced it with an Ultegra 6700 chain before the posted videos. The writing is on the outside. Is that the only thing that matters? I imagine there isn't an up or down to the chain also, just inside/outside. The fact that it happened with an old and new chain should be telling...somehow.

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.

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.

Thanks, I'll do that.