New Cassette Issue

DA and Ultegra are compatible, as long as you're talking the same number of cogs in each (9-speed and 9-speed, etc.). At most a slight tweak of the barrel adjuster should dial it in.

However, if your old chain is worn ("stretched"), it might not mesh with a new cassette. Try your old cassette on the new wheel and see if the feeling goes away. If it does, then I'd suspect a worn chain.

Could also be that your delimeter screws need to be adjusted for this wheel. 

I think we have the same problem, and pretty sure it's the chain that's not compatible. I have the same setup you have P2C and either a 7900 or 7800 DA chain. I recently got a Ultegra cs-6700 cassette thinking it should work fine, but it doesn't.

Ultegra CS-6700 cassette was re-designed and I believe needs the Ultegra 6700 10spd chain.

If you don't have the right chain it reacts the way you described, very rough and noisy.

You also have to make sure the stamped side of the chain link is facing out, since it is a directional chain.

Just to prove this, I swapped out the cassette with my 105 and DA cassettes (older) and they work fine (smooth).

I appreciate the help everyone.

I'm thinking it's a chain issue for sure, especially since the other fellow experienced the exact same scenario with his P2C.  My first go around at installing the cassette I actually missed the first spacer (stuck on the package) and it didn't tighten properly.  I caught the missing spacer and it cinched up solid as a rock on attempt #2.  

I certainly didn't realize chains were that special!  So just to confirm, a brand new chain will not work with my old cassette/wheel? That is not ideal as I was hoping to keep my stock rear wheel for trainer sessions, and the Jet's for certain outdoor rides/obviously races.  Thems the breaks I guess...

Thanks again

I'm going to dig into this problem a bit more, I'll let you know what I find out....

kinda of a mystery really, I had assumed the 6700 stuff was compatible.

I did find a few other forum posts on the net that alluded to this issue too...so others have experienced it.

Just not exactly sure why...

They are 100% compatible.  I use 7800 shifters with 6700, 6600, and SRAM cassettes with no problem (with either SRAM or Shimano chains of misc. levels).  Usually an adjustment or old chain/new cassette wear issue.

but whats strange is the 105 and DA cassetter work fine. other than a possible defective 6700 cassette, I have no idea what it would be.

I frequently change wheels and cassettes on my bikes.  In most cases I do not have to adjust the rear derailleur.  But as has been mentioned in some cases you need the spacer and other cases you do not.  Generally Shimano spacer and SRAM not.  But I have found this to not always be consistent.  Have you for sure checked this?

I have also collected spacers that vary in thickness a tiny bit.  I was able to get them from my LBS.  I honestly do not know where you get them otherwise.  I keep track of which spacer with which cassette with which wheel.

I am embarrass to mention something else to consider as I did it once.  I had interchanged a 10 speed and 9 speed cassette.  After I worked for a while trying to get it to work I brought it into the LBS.  Wow was that embarrassing.  But I now will never make that mistake again.

If you can get it to work with the spacer it is a lot easier when switching wheels.  You really do not want to have to adjust on wheel changes.  If you are like me you use your training wheels and then switch to race wheel for races.  It is a huge hassle to have to then adjust rear derailleur before a race.  Worst is bringing it into the LBS if you don't adjust yourself.

BTW, the adjustments are actually extremelly easy once you invest some time to learn.

Also, I have never had a problem interchanging cassettes, as long as same number of speeds, of different brands.  They are compatible.  I mix SRAM and Shimano components all the time.  Chains, deraileurs, cassettes and had zero compatibility issues.  I am willing to bet that is not the issue.  I have mixed Force, Red, Utegra and Dura Ace without issue.

With a new cassette I would put on a new chain.  It is also handy to have a bunch of thin spacers if you don't want to adjust the rear derailer.  I use them but I am running an older setup.

With a new cassette I would put on a new chain.  It is also handy to have a bunch of thin spacers if you don't want to adjust the rear derailer.  I use them but I am running an older setup.

following up on an old thread.

changed my chain today, and noticed significant stretch, almost a full link comparing the old chaing to new chain.

pretty sure this is culprit to the noisy drivetrain issue.