[ToddW]

CAn I run an Ulterga cassette in place of my XT? Are the splines the same on the free hub?

Thanks,

 

[Shayne]

Yup

All Shimano 9spd cassettes have the same spline

 

[ToddW]

Sweet,

I've ordered a 9 speed road cassette and a medium cage derailuer. I'm going to try something with a little closer gear ratio for a while. I'm used to my single speed so I don't the a taller ratio is going to hurt me and I'm hoping for a quicker shifting set-up.

Thanks,

 

[kdiddy]

My Ultegra 12-27 didn't shift as quick as my XT 11-34 on my SRAM XO equiped bike. I partly blame the fact that the idler pulley doesn't track as close to the cassette, especially in the larger cogs. I also didn't shorten the chain for the smaller cassette.

 

[shiggy]

My Ultegra 12-27 didn't shift as quick as my XT 11-34 on my SRAM XO equiped bike. I partly blame the fact that the idler pulley doesn't track as close to the cassette, especially in the larger cogs. I also didn't shorten the chain for the smaller cassette.

That would be partly because you did not shorten the chain and mostly because the XO derailleur is designed to track the angle of cassettes with larger cogs. Other than cage length the latter is the major difference between road and mt rear derailleurs.

 

[SteveUK]

Further to Shiggy's response, I'd recommend switching to a super-short cage Ultegra derailleur, or SRAM's X9 super-short cage if you're on SRAM 1:1 shifters. My Ultegra 12t-27t didn't always play particularly well with even a short cage XT, but matches nicely with the Ultegra. I now use the Ultegra derailleur with an 11t-23t DuraAce cassette, shifts brilliantly.

 

[kdiddy]

Yep, short cage MTB derailleurs are really intended for double or single rings up front, not road cassettes. For optimum performance with a road cassette, you should use a road derailleur. Unfortunately SRAM road stuff is reportedly a different ratio than the MTB stuff, so it's not perfectly compatible like Shimano stuff is.

 

[Shayne]

How Are They DIfferent?

That would be partly because you did not shorten the chain and mostly because the XO derailleur is designed to track the angle of cassettes with larger cogs. Other than cage length the latter is the major difference between road and mt rear derailleurs.

Hey Shiggy,

How do road and mtb derailleurs differ in design? I've just measuerd up a few (STX long cage, 105 mid cage, Ultegra short cage, XT short cage, Record short cage) and aside from the obvious cage length difference they all measured out within 1mm of each other.
I admit I had no idea what to measure but I compared, center of mounting bolt to center of left side of parallelogram. parallelogram length c-c on pivots, width between parallelogram plates, and mounting bolt to cage pivot as would be in a plan drawing.

 

[shiggy]

Hey Shiggy,

How do road and mtb derailleurs differ in design? I've just measuerd up a few (STX long cage, 105 mid cage, Ultegra short cage, XT short cage, Record short cage) and aside from the obvious cage length difference they all measured out within 1mm of each other.
I admit I had no idea what to measure but I compared, center of mounting bolt to center of left side of parallelogram. parallelogram length c-c on pivots, width between parallelogram plates, and mounting bolt to cage pivot as would be in a plan drawing.

Road derailleurs are designed to track the shallower angle of a cassette with smaller cogs...

... (mt) derailleur(s are) designed to track the angle of cassettes with larger cogs...

 

[Shayne]

Uhhhh.....Thanks