identical cassette not compatible???

Not all wheels/hubs are identical. There is a cable adjuster at the rear of the derailleur, if confident, adjust. If not, get the LBS to show you how to set it up for both wheels.

yeah, it can sometimes take less than a mm of difference anywhere across the hub to throw the gears out

Thanks guys, i have never had to change the rd settings as have always used the same wheel. Are you talking about the high/low adjusters, and is it possible to have it setup to suit both wheels???

Cheers,

Andrew

Its possible your chain has stretched! - get it measured at LBS

SEGFTG said:

Thanks guys, i have never had to change the rd settings as have always used the same wheel. Are you talking about the high/low adjusters, and is it possible to have it setup to suit both wheels???

Cheers,

Andrew

G'day Andrew, long time no see!
Like Oz said, it doesn't take much. You'd have to compromise to get both wheels working, and neither would be working optimally. High/Low and cable tension need to be adjusted.
Your bikes not that old so I reckon your chain's fine.

SEGFTG said:

. Are you talking about the high/low adjusters, and is it possible to have it setup to suit both wheels?

Yep. The only possible problem would be the condition of the chain (wear/"stretching"😉 suiting both cassettes. You've just gotta make sure the outer spacing between the smallest cog and the lock-nut on the axle are as close to exactly the same as you can get it.

flipper said:

G'day Andrew, long time no see!
Like Oz said, it doesn't take much. You'd have to compromise to get both wheels working, and neither would be working optimally. High/Low and cable tension need to be adjusted.
Your bikes not that old so I reckon your chain's fine.

Hey Phil,

Has been a while! How are the hills treating you?
Seems to be a simple case of adjusting the b tension, guide pulley was a bit too close to cassette, indexing and high/low settings are fine. Park Tool and Sheldon to the rescue once again!

SEGFTG said:

Have just bought a new wheelset with a ultegra 10 speed 12-27 cassette, which is what I also have on my current wheelset.
For some reason the new wheelset cassette shifts poorly and the chain seems to be rubbing on sprockets.

Any ideas what might cause this, I hoped that the wheels would just change over with no adjustments required.

Thanks,

Andrew

Is the spacer installed correctly? For Shimano 10s cassettes with 11T or 12T small cog, there should be a spacer installed between the large cog and the freehub body (as well as the lockring spacer between the small cog and lockring).

Even if everything is installed correctly, if the hub is a different brand than your first wheelset, it is common to have some differences in cog alignment between wheelsets that may require some RD fine tuning. With 10s systems, just a little misalignment can cause problems, unlike the old days when 6s and 7s systems tolerated a lot of error in the system.

SEGFTG said:

Hey Phil,

Has been a while! How are the hills treating you?
Seems to be a simple case of adjusting the b tension, guide pulley was a bit too close to cassette, indexing and high/low settings are fine. Park Tool and Sheldon to the rescue once again!

Sounds like you've sorted it pretty well then 🙂
The hills... hmm, still hurting me 😉 It's been bloody ages, I don't think we've been for a blast at all this year :eek:
You been up here much lately?

flipper said:

Sounds like you've sorted it pretty well then 🙂
The hills... hmm, still hurting me 😉 It's been bloody ages, I don't think we've been for a blast at all this year :eek:
You been up here much lately?

Not as much as I would like... The next little screamer is due in a few weeks so time has been limited, and I guess will continue to be for a while🙁
Did you end up doing anything about a new bike?