Mountain Bike Reviews Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter · #1 ·
I know there is a similar thread, but my question is a little different. Could I run one of the new sram x9 10 speed rear derailers with everything else being 9 speed (cassette, chain, shifters). It's my understand that since SRAM uses a 1:1 ratio between pull and derailer movement (ie actual shift indexed distance is determined by the shifter) that any 1:1 derailer should work. Right...?
 

·
Registered
Joined
·
45 Posts
Discussion Starter · #2 ·
sorry, looks like SRAM's "Exact Actuation 10 Speed" is some bull**** and no long 1:1. To SRAM I ask this-- why not keep the 1:1 ratio and make the shifters pull a bit less per shift?
 

·
Never trust a fart
Joined
·
4,543 Posts
The 10 speed MTB has the same pull as the road components. But its still 1.1. This is pulled directly from SRAM's website from the X9 10speed description.

Exact Actuation
When we launched our road technology from scratch we reapplied our MTB proven SRAM 1:1 actuation ratio (shifter cable travel : derailleur movement) for 10 speed rear shifting. EA helps to simplify/stabilize the uneasy act of balancing rear derailleur hanger design, tight cog spacing and exact cable tension. The result: the easiest index shifting system to set up and it stays that way.


9 speed doesn't have exact actuation, only the 1.1 pull ratio. So you can only use 10 speed derailleurs with 10 speed shifters - both road and mountain.
 

·
Premium Member
Joined
·
48,238 Posts
dullertap said:
I know there is a similar thread, but my question is a little different. Could I run one of the new sram x9 10 speed rear derailers with everything else being 9 speed (cassette, chain, shifters). It's my understand that since SRAM uses a 1:1 ratio between pull and derailer movement (ie actual shift indexed distance is determined by the shifter) that any 1:1 derailer should work. Right...?
No. The SRAM 10-sp RD will not work with 9-sp.
 

·
Registered
Joined
·
45 Posts
Discussion Starter · #5 ·
Am I crazy for thinking this? I could use my 1:1 9speed derailer in an 8 speed setup, back in the day. What's with calling it 1:1 if it is not.... Or has anybody actually attempted this?
 

·
Former Bike Wrench
Joined
·
15,976 Posts
7, 8, and 9 speed SRAM were are 1:1...10 speed uses their Exact Actuation that they use in their road stuff. While it is similar to 1:1 it is not the same

If it makes you feel any better you could use 7, 8, and 9 speed Shimano intermixed too, but their 10 speed MTB rear derailleurs are not compatible either.
 

·
Premium Member
Joined
·
48,238 Posts
dullertap said:
Am I crazy for thinking this? I could use my 1:1 9speed derailer in an 8 speed setup, back in the day. What's with calling it 1:1 if it is not.... Or has anybody actually attempted this?
First, 1:1 is a marketing creation. The actual ratio has never been exactly 1:1.

Second, the RD and shifter still have to be designed to work together.

SRAM saw a need to change the spec for 10-sp, just as they did when they designed their own derailleurs in the first place. Nothing you can do about it.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top