Cyclocross - convert mtb to 'cross bike

and running 700 wheels...

I think I need these (http://www.mavic.com/ewb_pages/p/produit_accessoire_REHAUSSEURS_DE_TASSEAUX.php?gamme=asphalte) but I don't know where to get them. Anyone know where I can find them?

I have a mountain bike (Trek 900) that is closer to a road bike fit, and I'd like to make it into a 'cross bike, I have derailleurs for my 700c set (21 speed - shimano RSX) and was planning on using those with some friction bar end shifters.

I haven't quite figured out what I'm going to do with the bars, I have Fuji ergo drops that I like and might put on, but I figured I'd find the brake bridges first.

I've been there, with a Trek 930. Good times, almost as fun to convert as it was to ride.

You've got two easy options with the brakes...

1.) The brake bridges you mention are available at speedgoat (http://www.speedgoat.com/product.asp?part=108671&cat=30&brand=155). Not sure how big a tire you can fit in there.

2.) Some adjustable height cantis have enough play to fit 700c wheels with the 26" wheel bosses. I used Avid tri-aligns... Onza's (http://cgi.ebay.com/NIB-Onza-H-O-Canti-brakes-Cyclocross-brakes-FR-RR_W0QQitemZ110129115009QQihZ001QQcategoryZ42331QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) are commonly available on ebay.

For the derailleurs, make sure that the cable routing matches your FD. Mine had cable stops for a top-pull front, so I used the Deore FD for a while. It worked just fine with bar-ends.

Have fun!

Remember that your frame geometry is different, you will most likely aslo need a real short stem

Thanks for the info justinb - that's perfect... I'm kind of getting stoked about this project, even though it's just in the inkling stages right now... lots of testing to see if it'll really be feasible.

milice - not sure about that yet, but it's got a humongous stem on it now and when I put drops on it I'll be even more stretched out, so I'll have to swap the stem for sure... I thought I'd start with the wheels brakes and drivetrain and then go on to shifters, brakes and handlebars.

Why do you need the 700c wheels? You could leave it out. The derailleurs you mention will work fine with 26" wheels.
Cycling plus did an article on converting an MTB to a cross bike. They used an old Dawes frame, and had the studs moved up the fork and chainstay. If you have a framebuilder nearby, you could do that...

acorn makes a good point... you don't have to have 700c wheels, unless you want them. There is a modest selection of 26" semi-slick semi-skinny tires out there. Kenda Kwick 1.6" is one good example. There's also a Club Roost model, and I think both Conti and Schwalbe make knobbies in 26x less-than-1.5"

Does this mean you are going to start coming to cross practice? I remember another article that listed mtb wheels that met the requirements for most of the racing in our area.

and running 700 wheels...

I think I need these (http://www.mavic.com/ewb_pages/p/produit_accessoire_REHAUSSEURS_DE_TASSEAUX.php?gamme=asphalte) but I don't know where to get them. Anyone know where I can find them?

I have a mountain bike (Trek 900) that is closer to a road bike fit, and I'd like to make it into a 'cross bike, I have derailleurs for my 700c set (21 speed - shimano RSX) and was planning on using those with some friction bar end shifters.

I haven't quite figured out what I'm going to do with the bars, I have Fuji ergo drops that I like and might put on, but I figured I'd find the brake bridges first.