Bicycle Mechanics - Paranoid Bike Compatibility Question

ok so im building a bike and just realized that my rear deraileur (8sp) was not compatible with the rest of my set up (9sp) so i'm a bit paranoid with the rest of my setup. i just bought the new tiagra 9sp shifters and i have a compact double crankset. does it matter that the left hand shifter is a triple?

First, assuming its a Shimano 8-speed rear derailleur and NOT Dura Ace, it will work fine with your 9-speed shifters, cassette and chain. I'm currently using a 105 8-speed rear derailleur on an otherwise all 9-speed 105/Ultegra bike and it shifts perfectly.

Second, Tiagra 9-speed (like both 105 and Ultegra 9-speed) brifters are both double and triple compatible.

ok so im building a bike and just realized that my rear deraileur (8sp) was not compatible with the rest of my set up (9sp) so i'm a bit paranoid with the rest of my setup. i just bought the new tiagra 9sp shifters and i have a compact double crankset. does it matter that the left hand shifter is a triple?This is an imaginary problem.

There's no such thing as an "8-speed" derailer except in the imagination of the marketeers.

See: http://sheldonbrown.com/speeds for more general info on interchangeabilitude.

Sheldon "Not To Worry" Brown

+-----------------------------------------------------+
| If one lets fear or hate or anger take possession |
| of the mind, they become self-forged chains. |
| --Helen Gahagan Douglas |
+-----------------------------------------------------+

This is an imaginary problem.

There's no such thing as an "8-speed" derailer except in the imagination of the marketeers.

See: http://sheldonbrown.com/speeds for more general info on interchangeabilitude.

Sheldon "Not To Worry" Brown

+-----------------------------------------------------+
| If one lets fear or hate or anger take possession |
| of the mind, they become self-forged chains. |
| --Helen Gahagan Douglas |
+-----------------------------------------------------+


Sheldon invents yet another word. "Interchangeabilitude" I like it. Webster just can't keep up.

Sheldon invents yet another word. "Interchangeabilitude" I like it. Webster just can't keep up.

Give Webster a few years, it'll be in there... or better yet, there should be "specialty" dictionaries such as a cycling one.

This is an imaginary problem.

There's no such thing as an "8-speed" derailer except in the imagination of the marketeers.

Sheldon "Not To Worry" Brown
Since my 105 rear derailleur was bought when 105 was strictly an 8-speed goup, it is de facto an "8-speed rear derailleur". Nevermind that it will index just fine with 7,8,9 and 10-speed components, it's still an 8-speed derailleur. So there! :p

There's no such thing as an "8-speed" derailer except in the imagination of the marketeers.

Well, the finish will match the finish of other components from that group, most of which are #-of-speeds specific. But that's where the compatibility issues end. Same thing applies to cranksets (at least modern ones) as far as I know. My wife's road bike, which I converted to an 8 speed, is still using the original crank from when it was a 6 speed.