Elementary front derailleur question

What front derailleur do I need for a Specialized Tricross Sport? Will “Shimano America Dura-Ace 7800 Front Derailleur - Braze On - Double” work for me?

It is a 9-speed bike.
Here is what the Specialized website says about the derailleur : FRONT DERAILLEUR= Shimano Tiagra, 31.8mm clamp, bottom pull
Here is a linky for the bike: http://www.specialized.com/bc/SBCBkModel.jsp?spid=38443&eid=123

You need a clamp on not a braze on. If your bike has a triple you can’t use a double.

You need a clamp on not a braze on. If your bike has a triple you can’t use a double.
Thanks!

You need a clamp on not a braze on. If your bike has a triple you can’t use a double.
To confirm, will this work? http://mikesbikes.com/itemdetails.cfm?ID=1876&Affiliate=7

You need a clamp on not a braze on. If your bike has a triple you can’t use a double.
To confirm, will this work? http://mikesbikes.com/...1876&Affiliate=7

You’ll want to confirm that with someone smarter than me. You need to be sure it’s bottom pull and that it’s OK for 9 speed because I’d guess that’s for 10 speed.
I’m not sure if 10 speed is good on a 9 speed bike because the chain is wider.

You need a clamp on not a braze on. If your bike has a triple you can’t use a double.
To confirm, will this work? http://mikesbikes.com/...1876&Affiliate=7

You’ll want to confirm that with someone smarter than me. You need to be sure it’s bottom pull and that it’s OK for 9 speed because I’d guess that’s for 10 speed.
I’m not sure if 10 speed is good on a 9 speed bike because the chain is wider.
a 10 speed front derailleur works with 9 speed

Can I ask you guys to post a linky for what I need? I wanted to get Ultegra or DA I guess, but whatever fits on a cyclocross bike is good for me.

For a cross bike, get a 105 (or whatever other deal you can find)! You won’t likely shift from the small ring anyway during a cross race.