Bicycle Mechanics - Pulleys- do you replace them ?

I was reading somewhere that road bikes should have their pulleys replaces every year,
and MTBs even more often.
Actually I noticed that one of my pulleys (the one that is under the cogs) is quite worn but the other pulley looks like new.
Do you replace your pulleys ?

i replace my rollers every year or about 3000kms...

check out those cool aluminum pulleys w/ sealed bearings.. I think attack makes one.. available in blue, green, yellow, red and black...
:)

Since I've got new dérailleurs on both bike I won't need pulleys for a while but if I were in the market I'd nab a set of these (http://www.nashbar.com/profile.cfm?category=83&subcategory=1038&brand=&sku=1535&storetype=&estoreid=&pagename=)

I have heard that aluminum pulleys are loud. I fI notic my pulleys wearing out, I'm gonna put stock shimano in.

I never replace mine unless they cause a problem. Once a year is proberly a bit excessive. My last set lasted more than 4 years of muddy riding before the balls fell out of the cartrige bearing. They only take slack from the chain so tooth wear shouldn't be a problem.

Other than the noise the alu pullies with cartridge bearings don't provide any float. Normal top pullies are designed to move from side to side a little bit to aid smooth shifting. The higher end shimano pullies are also better sealed.

IDo you replace your pulleys ?

I do. The pulleys in my Shimano XTs are journal type bearings (not ball or roller bearings). I clean and lube them every 6 months. After a couple of years of mountain riding, I noticed the bearings were looking a bit beat up. The rubber dust seals were trashed and I assume dirt got into the bearings. Being low on the bike, the pulleys get a pretty good dust bath. Plus I think in general the poor pulleys get neglected. It's not one of the sexier components on the bike.

The last set of pulleys I bought were Tacx (maybe $12 for the pair). Years ago, I used aluminum Bullshot (I think) brand pulleys. They had a cool anodized look.

I have never replace my rear derrailluer pulleys, never cost me a problem