TakeBack

2006 Bianchi Volpe
I recently changed the stock tiagra set to a used dura ace set that a friend gave me (7700 group).
the FD doesn't fit my seat tube w/o a shim so I still have my old FD on.

With my old set the chain would skip- to me it looks like it was skipping on the cassette.
I changed everything out and put a new chain on- same problem still.

Most pronounced when in higher gear but I seem to notice it on all cogs.

The new set is used so perhaps there is wear on those teeth as well, but I am still a novice at drivetrain and not sue what to troubleshoot next.

contango 

If it worked before but started skipping when you put the new group, maybe the RD needs adjusting. You may need to adjust the limit screws and/or the cable tension.

c_bake

If the chain is actually skipping, as in jumping a tooth on the rear cog, then replace the cassette. RD adjustment will not fix the problem.

cny-bikeman

You changed both the rear cassette and the chain, so quite possible the old skip was due to old chain and new skip due to new chain on old cogs. Best way to tell is to put on a rear wheel that has a fairly new cassette on it. If it's worse in higher gears then is not likely adjustment - that only leaves wear.

Ronno6

EZ rule of thumb: measure center to center distance for 12 links of chain. (Actually that's 24 pins. A link consists or 1 inner plate + 1 outer plate.)
New chain will measure 12". When length is 12 1/16", you should be able to install a new chain and use the old cassette.
When the chain "stretch" gets to 12 1/8+, it's time for a new chain and cassette.
Of course, if the cassette cogs are worn, it's time for new cassette and chain.
Park Tool makes a tool for checking cassette wear.
Of course, it is important that you are using a chain that is suited to the # of cogs on the rear cluster.
5speed,6speed, 7+8speed,9speed and 10speed chains are all different widths. (7 and 8 are the same.)

cny-bikeman

OP already stated the chain is new....

wrk101

95% of the skipping I see on a new chain is a worn cassette. I am not clear on whether you swapped cassettes and put on a used one with your group or not. And even on a cassette that does not skip with the original chain, I will see it with the new chain. Skips tend to be on hard gears, so I have a test hill a block from the house where I mash up the hill.

hueyhoolihan

it's not unlikely that the set that was given to you for nothing was worn out. you have to start over diagnosing the skipping on the new (to you) set. first step is to determine exactly whether it is skipping on the chainrings or the cassette. then which chainring or cog(s). then buy new parts as needed.

you stated that you have a new chain already, so unless it is incompatible that is not the issue.

Tuc

If it skips enough in just a short amount of time, it can ruin the cogs whether or not it was the original problem. It might be the tension on the RD from the cable housing, or a sticky cable on the RD.

ultraman6970

Those shimano RDs have a B-screw?? remember the old ones had one, if it shifts fine while setting everything up, and under load kind'a start crapping up then there is a big chance the B-screw (if has one) needs to be adjusted, actually bring the RD closer to the cassette.

Checked the catalogs and that thing has a B-screw... maybe thats the problem since the chain is new and stuff??

contango 

Not necessarily. When I replaced my chain and cassette the new chain skipped on the new cassette. In the smaller sprockets it would routinely skip and re-engage, sometimes with the correct sprocket and sometimes with a different one. Adjusting the RD fixed it.

Tuc

In my case the skipping was caused by the previous owner putting too short a RD cable housing on the rear just before sale with some frayed cable hanging up inside it. Tried three chains and another cog set to find the real issue.