ruirui

.... switch from 8 speed rapid fires to the shimano 8 & 9 speed bar end shifters? can I use the existing cables or would i have to replace the cable to a new set? what about brake lever & brake cable, are those fairly easy to change as well?

i'm thinking about changing the flat bar on my sirrus to the Syntace Stratos Bullhorn Bar and attach my C2 bar onto it as well. thus i'll be requiring the Syntace Space Control Brake Levers along with the cables and 8/9-speed Shimano Dura-Ace bar end shifters.

what do you guys think?

EDIT: btw, how do you know how wide of a handle bar you need? i remember reading somewhere that it should be about the same width as your shoulders from side to side. is that right?

Retro Grouch 

It's a good policy to replace the cables and housings whenever you change shifters or brake levers. In this case, I doubt you'll have a choice because the cable lengths are going to change a significant amount. You should also plan on a new stem because the clamp size for your new bar will be larger.

ruirui

humm... that's what i was guessing about the cable length. however, i've been thinking perhaps i can just get a drop bar instead.

Retro Grouch 

You'll still have to look around to find one with a 25.4mm clamp. Nitto and Dimension are two brands that come to mind. Retail price should be about $25.00. Most drop bars have a 26.0mm clamp. I've heard of guys "crunching" a drop bar into a flat bar stem, but I don't think that it's a good idea to impose those point stresses on an aluminum handlebar.

ruirui

hummm good point there retro. i'll be sure to keep that in mind.