gluckster2

I currently have a Ultegra double (not compact), Triple STI's, and 9 cogs in the back. If I'm careful, the chain doesn't deraill when I down shift. BUT it's starting to be a pain in the ass.

Performance is having a sale so it got me thinking.

Will the Ultegra rear derailleur help at all? Will it even work?

Is there a way to rig it up?

Or do I have to drop 300 bones to get the 105 or Ultegra STI?

Thanks in advance!

barba

If I am understanding you, you need to set the limit stops correctly on the front derailleur. I don't think that a rear derailleur is the issue.

gluckster2

So is I set the limit stop correctly, nothing will happen when I click over the third time?

Can this be true?!? A simple answer that doesn't cost a ton of money?!?!

barba

Yes. Just adjust it so that it cannot over shift.

nobrainer440

It won't let you click over the third time. You'll hit the limit screw, the cable will go taut, and the shifter will stop.

cyccommute 

The cable will go slack (downshifts release tension on the cable). You'll have that third click but it won't do anything.

GGDub

You might need a long cage derailler in order to take up the chain slack when you're in the little ring. If you're current Tiagra one is a short cage then you should be fine.

edit: I'm a dumba$$, I didn't read your post correctly. The cage has nothing to do with your problem.

cyccommute 

Yes. It is that simple. Move the derailer over to where you don't rub on the big cog rear/little chainwheel front. Tighten the limit screw until the derailer moves outward. You are done. If you rub on the inner plate of the derailer, move it inboard a little...very little. Go ride.

The rear one works the same as the front but you shouldn't have to mess with the limit screws unless you have a new derailer.

nobrainer440

Ah yes. I was thinking of setting it up for the 2 small rings. Couldn't you set it up either way?

barba

If I remember correctly, there is no double or triple specific 9 speed Tiagra STI. It is only a matter of setting the limit screws to make it work with either.

gluckster2

Man that makes my life SOOO much easier (and cheaper).

Huh... so then when is a rear derailleur specificly double or triple:

https://www.performancebike.com/shop/...tegory_ID=5116

https://www.performancebike.com/shop/...tegory_ID=5116

I guess the same questions could be asked for the STI's as well.

Just curious.

Thanks!!

cyccommute 

If you are going to go with a double crank and something up to an 11-27 in the rear (you can push them to a 29 tooth cog), go with the double. If your area is hilly and you need lower gears but don't want the double, and would like to run say an 11-32, go with the long cage derailer. However, mountain bike derailers do wide range, low geared cassettes better than road derailers do. They have a bit wider range.

barba

The "triple" rear derailleur has a longer chage (the part that hangs down with the pulleys) so that it can take up the extra slack in the chain created by using the granny gear. You can use a tripe rear derailleur on a double set up, but not the other way around (unless you had very little range in size between the biggest and smallest chainring on your triple, I suppose).