Singlespeed & Fixed Gear - Difference in these Shimano BB's?

Can someone tell me the difference b/w these Shimano bottom brackets? Which one is a good mix of cost/performance? Do the good ones just spin slightly smoother?

Here's a long list of them....

http://aebike.com/page.cfm?PageID=30&action=list&Category=173&Brand=367&type=T

The UN53 will be fine, altho if I was going to ride the bike for a long time I would go ahead and get the UN73, it has an alloy fixing cup rather than the plastic one the UN53 comes with.The plastic works OK but if you cock the tool it can crack the teeth off and sometimes when you tighten it up it tries to trap the tool and you have to rock it free.. The 25s and 27s are barely worth the price.

all I have to say is just be careful w/ the plastic cups when installing your BB.
i've busted 1 cause my wrench slipped and I cracked the cup.
also cause I was too lazy to reach over to get the proper shimano BB spline tool.

and so my paperweight collection becomes larger.

*edit* I agree w/ the rev. play it safe it get the UN73's.

The UN53 will be fine, altho if I was going to ride the bike for a long time I would go ahead and get the UN73, it has an alloy fixing cup rather than the plastic one the UN53 comes with.The plastic works OK but if you cock the tool it can crack the teeth off and sometimes when you tighten it up it tries to trap the tool and you have to rock it free.. The 25s and 27s are barely worth the price.

my 53 has an alloy cup

ALSO another note:

if ya went w/ the plastic cups.

tighten the drive side cup (alloy) 100% and ONLY tighten the plastic cup around 80%.
and also don't be surprised if the plastic cup doesn't seat on the BB face.

some people hate them some people love them, but for the money go for a miche track bb. in my opinion they are a great bb for the money.

Moz... miche is iso... isnt jis.. shimanos are jis and maybe he is looking for something in jis u know... I mean it will work maybe but who knows who the chain line will be...

ohhh duh. im ********.