# Di2 7970 rear der shifting issue



## veloci1 (Nov 29, 2005)

I am having issues with my rear shifting. When on the small chainring , all shifts are perfect. While on the big chainring The chain sounds like it wants to skip, but, it does not. I tried adjusting it but if I get it right on the big chainring then the shifting on the small chainring suffers. 
I installed a new hanger, just in case and the chain and cassette do not have more than 1500 miles. 

Btw, I just got the 7970 installed on the bike. Got a great deal on it and could not pass it up. But, I am a little disappointed. My red SRAM was always perfect. 


Help.


----------



## J.R. (Sep 14, 2009)

Have you adjusted it per these instructions?
http://techdocs.shimano.com/media/t...70/SI-6RX0A-005-ENG_v1_m56577569830707675.pdf


----------



## veloci1 (Nov 29, 2005)

thank you JR for the quick reply. i did follow the instructions and it seems like it is doing the same thing. i will start fresh and see what happens today. i noticed that the front der was not set up correctly. i fixed that . but, did not have a chance to test ride the bike.

i will post anything i find out.it is just odd that it happens on the big chainring only. you would think that if the der is not adjusted correctly, it would happen on the small chain ring too.


----------



## veloci1 (Nov 29, 2005)

I m ready to give up. I cannot get that rear shifting tuned. I m wondering if I install the 11 speed spacer correctly on my wheels. They are 11speed and came with a spacer. Am I supposed to use the spacer that came with the wheels in conjunction with the spacer that came with the cassette? I have not tried but I will if one of you guys has had experience with the ten speed cassette on a 11 speed hub. 
I will drop off my bike at the lbs tomorrow andt ask them to check the bb spacers since I have a Cannondale Hollowgram

I am thinking I should have stayed with SRAM red. Never had an issue by like an idiot, I had to mess with it.


----------



## r1lee (Jul 22, 2012)

Yes use both spacers.
So the 11 to 10spd spacer and the one that comes with the cassette.


----------



## Dunbar (Aug 8, 2010)

r1lee said:


> Yes use both spacers.
> So the 11 to 10spd spacer and the one that comes with the cassette.


I only used the 1.85mm 11sp spacer on my hub with a 10sp 5700 cassette. I made my LBS try the extra 1mm spacer but they couldn't even get the lock nut to start threading onto the hub. From what I've read you use enough (one or two) spacers so that the cassette is very snug,


----------



## r1lee (Jul 22, 2012)

Dunbar said:


> I only used the 1.85mm 11sp spacer on my hub with a 10sp 5700 cassette. I made my LBS try the extra 1mm spacer but they couldn't even get the lock nut to start threading onto the hub. From what I've read you use enough (one or two) spacers so that the cassette is very snug,


Strange, on my old 10 spd I ran them both. It was on a set of Reynolds aero 58 with the 11spd dt Swiss hubs. Ran it on my 6770, had to use both spacers.

I was able to thread it on and programmed the 6770 properly.


----------



## veloci1 (Nov 29, 2005)

I used both and was able to secure the cassette. The shifting is better, but, not where it should be. That tells me that this is an alignment issue. My thought from the beginning has been that the rear triangle on my replacement evo frame is off. I can see how the tire is closer to the left chain stay than the right one by about 2mm.
I will have the lbs check that out and take it from there. 
I will let you guys know..


----------



## veloci1 (Nov 29, 2005)

well,i got tired of dealing with the LBS and took upon myself to replace the chain and chain rings with brand new ones. the problem is gone. i m assuming it was the chain, though it was measured by the LBS and was told it was well within the limits. like i said, it only had 1500 miles tops. 
the wheels aligment is still off, but, that is something i will have to look into a little further. 

thank for al the feedback and sugestions.


----------



## thumper8888 (Apr 7, 2009)

May have been chain length, sounds too short maybe? did you change length when swapped out chain or go with same?


----------



## veloci1 (Nov 29, 2005)

Same length. I am sure it was the chain worn off. I installed the cassette 
on my son's bike and he has not had any issues. The chain measured ok
When checked. Who knows? 
I am just glad it is fixed now.


----------

