nocondorfx

What are the most important components.... which parts(rear deraileur, brakes, etc.) would i want to upgrade first?

Jakey

I would say, brakes, rear derailer, cranks (if only to shave weight) and shifters.

I know in Campy, my record brakes stop me alot faster than my centaur ones. There is a definite difference. I assume its probably the same with Dura Ace brakes over say 105.

Az B

I would have to say that you're quite wrong. Assuming that both brakes have the same pads and you're using the same set of wheels and tires, there should be no difference in the actual stopping distance. The major factors in stopping are the friction between the pad and rim, and the friction between tire and road.

The DA brakes may give you better feel, (I don't think so, but others may not agree) and they are lighter, but they're not going to stop you faster.

To answer the OP, the component set has to work together. It's impossible to say what you should upgrade first without knowing exactly which components you already have. With the possible exception of wheels, which are generally the first and most important upgrade, the entire bike's setup must be taken into consideration.

Az

Jakey

Using the same wheels, I feel like I stop on a dime with the record compared to the centaur. Not sure of the pads, they are the stock ones that came with the brakes.

roadfix

In general, if you're looking for performance, wheels.....and if you're looking for comfort, saddle....
The OP's intent is too vague.....

nocondorfx

well i plan on doing wheels and saddle first. but i was just speaking about groupo components(shimano stuff) I juts got a bike and it has tiagara front deraileur, and 105 everything else.(9speed) I'm sure they'll do fine, since im brand new to this thing, but when i get some money to throw at it... what will i want to upgrade?

webist

My upgrades in order were - bar tape w/bar phat, saddle, wheels, pedals.

SteveE

I was gonna suggest legs,lungs, and heart as the best upgrades.

ggg300

wheels

ivan_yulaev

As far as bang for buck...

Tires (cheapest and most significant, by far!)
Wheels
Brake Pads
Group

jschen

It's either purely psycological or the effect of braking effort required. Either set of brakes should be fully capable of locking up your wheels and causing you to skid if you brake hard enough, so either is capable of a minimal distance stop (with tires just on the verge of skidding). The Record brakes may well require less effort to achieve this level of braking power than the Centaur brakes (I know Ultegra certainly requires less effort than Tiagra), but ultimately, your braking power is limited by traction if you are able to brake hard enough to skid.

Patriot

I always just keep riding the bike I have.

When I want an upgrade or something differant, I start with a new frame. Then I go from there.