canflyboy

My setup is full ultegra 6700 with an 11-25 cassette - no issues. I live in the flatlands and wanted to try a straight block. I found on deal on a DA CS-7800 12-23. I can't get the shifting dialed in with this cassette. What gives? Do I need a DA chain? It'll shift fine going up, but coming back down it sounds like crap. No matter how much tweaking I do, I can't seem to get good smooth shifts. I sometimes have to down shift twice and then once back up to make a clean shift. I put the CS-6700 back on and no issues.

Anyone else experience this?

Thanks

Canflyboy

Pb_Okole

Are you using the tiny spacer between the hub and the 7800 cassette?

canflyboy

Yep - spacer is in.

bobonker

I've run a full 6700 setup (with 11-28 for climbing) and then put in a 105 5600 11-23 for flats. No problems.

Is the 7800 cassette new?

Bob

2ndGen

Previous generation Shimano groupsets are not compatible much with the newer stuff.
Get rid of the 7800 cassette and get a 12-23 6700 cassette if you want the same cogs as the 7800.
Problem solved.


https://www.shimano.com/publish/conte...ty%20Chart.pdf

achoo

I started with a full 6700 setup, and it shifted fine on 5600, 6700, and 7800 cassettes.

I upgraded the RD-6700 to an RD-7800 when I bent the 6700 RD in a crash.

The 7800 RD shifts fine on 5600, 5700, 6700, and 7800 cassettes.

Three things to try:

1. Clean the chain.
2. Turning the adjusting ferrule a bit to allow the RD to move a small amount towards the 12-tooth cog.
3. Back out the B screw some.

thegunner

uh... no. shimano would love you to believe that so you buy newer stuff, but there is no reason why the CS7800 wouldn't work on the the 6700 system. spacing is exactly the same.

James1:17

is the chain directional...do you have in on the right way? is high and low limit adjusted correctly? have you turned the barrel adjuster counterclockwise to increase the cable tension any? btw, i'm assuming by up you mean to a higher, harder (smaller) cog and by down you mean a lower, easier (larger) cog.

2ndGen

He'd be better off with the 6700 cassette, don't you think?
It'll last him longer and will not require as much tuning.

2ndGen

Okay. Let me know when you can get a set of 7900 shifters to work with 7800 brakes or vice/versa.
I'd be happy to get that combo going. So far, hasn't happened yet.

scirocco

Sure, you're right. But that wasn't the OP's problem. What thegunner said was correct. The OP is not mixing and matching old gen shifters with new gen RD/FD or brakes, so should not have a problem. 10 speed cassette spacing has not chnaged between the generations.

I don't know what's causing the OP's problem, though...

achoo

Yeah, but he HAS the 7800 cassette.

BayAreaUser

Nope, he'd be better off getting rid of all the ultegra nonsense and upgrading to 7900 all together =P

Continue playing with the adjustments, i have the older 105 version on the caad9 and it works with a 7800 cassette. I know is not the same issue, but just goes to show that most of those parts (except shifters perhaps) are interchangeable.

2ndGen

2ndGen

Okay, but I was addressing your statement that "...shimano would love you to believe that so you buy newer stuff...".

rob!

I'm pretty sure that's only the case with shifters and derailleurs, but they want you to believe it's everything.

thegunner

no you didn't, you missed the part where i had CS before the 7800. i made no mention of anything else.

canflyboy

Couldn't leave it alone. Went back out a still couldn't get smooth, crisp shifts with the CS7800. I re-installed the CS6700 and with a small adjustment on the rear ferrule, smooth, crisp shifting up and down. The Ultegra chain is unidirectional and I have it on the correct way. I've mixed and match series (Ultegra, 105, event tiagra) and never had a problem like this. Duh?!?

2ndGen

6700 with the gears you want. Then be happy CFB.

grwoolf

Maybe a bad cassette? I've never tried a DA one, but have swapped between 5600, 6600, and 6700 without issues.

canflyboy

GOT IT!!!!! Took the chain off and cleaned it - re-installed, lubed and BACKED OFF the "b" screw adjustment significantly and that REALLY HELPED. ALL IS GOOD IN THE WORLD. CS7800 is now working with 6700 groupset.

Thanks all

2ndGen

Excellent!