front deraillur question

[1453]

So I got a frame that is the same as this:

http://i142.photobucket.com/albums/r117/calnra/2189291518_cd5cb4fc00.jpg

I got it cheap and new, and intend to use it as a trail bike(not hardcore stuff) and my girlfriend just got me a DHX 5.0 for it since I'm a lard ass(that can bench press a bit of weight).

What derailleur do I need for the front? I have a blackspire bash guard and just want to run the middle and small rings. The diameter of the "seat tube" is 31.8mm. I'm however a little confused with the top-swing and bottom swing stuff.

I have worked on my own bikes forever now but haven't used a front derailleur in 6-7 years.

Thanks,

1453

[Quo Fan]

That frame would take a 31.8 diameter, top-swing front derailleur.

[HAB]

That frame would take a 31.8 diameter, top-swing front derailleur.
Right. Also known as a 31.8mm low clamp derailleur by some. Also, it needs to be a bottom pull.

[1453]

thanks, folks.

Does top-swing=bottom pull?

[HAB]

No. Top swing refers to the relation of the parallelogram mechanism and the clamp. Top swing derailleurs have a low clamp. Bottom swing ones have a higher one. Bottom pull means that the cable comes at the derailleur from below.

[loco-gringo]

Any new standard top swing derailleur will work by Shimano. They use a clamping shim to work for all tubes and will have the ability to pull either direction. I know this is certain for Deore and XT. Pretty sure about LX, but XTR may be specific. Hope that makes a little sense.

[1453]

thanks a lot guys.