Road Bike, Cycling Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
89 Posts
Discussion Starter · #1 ·
I know that Shimano changed the cable pull ratio for the shifters with 7900. Does anyone know if the amount of cable pull is greater or less than 7800 for shifting? Has anyone actually tried using their 7800 shifters with a new 7800 front derailleur? Thanks.
 

·
Registered
Joined
·
156 Posts
More pull is required to move the 7900 front derailleur. I am currently using a DA 7803 (triple) shifter with a 7900 front derailleur and a 7950 compact crankset. It works fine except I have to push twice to shift up and down. I don't think a 7800 shifter would work well with a 7900 front derailleur.
 

·
Adventure Seeker
Joined
·
5,115 Posts
It'll work fine, you just need to set it up. What's changed is that you won't need the trim function for the outer chainring anymore.
I'm using a 7800/7800 with a 6750, and it shifts fine. It did take a little tweaking though.
 

·
Rub it............
Joined
·
3,833 Posts
The front pull required by the shifter to move the 7900 FD is different than the 7800 FD. I don't know the exact difference, but the ratio is different. You can only use the 7900 shifters with the 7900 FD. Unfortunately, this is the one thing that when Shimano says it isn't compatible with previous gen stuff, they are correct with this one.

However, all the Ultegra 6700 stuff will work just fine with DA 7800 and Ultegra 6600 without issue.
 

·
Adventure Seeker
Joined
·
5,115 Posts
frdfandc said:
However, all the Ultegra 6700 stuff will work just fine with DA 7800 and Ultegra 6600 without issue.
Which sounds very peculiar, considering the main difference is a couple of grams in weight. I guess if a 7900 FD won't work, then it'd be best to keep a 7800, which is lighter than the 6700FD.
 
1 - 7 of 7 Posts
Top