I just finished downgrading my Crux a couple of weeks ago. It used to be entirely Force components but I got sick of breaking expensive little bits. As parts have broke I'v slowly replaced them with Apex components. I weighed my bike today and it's still under 20 lbs!! While it's not super light I think it's pretty good considering every component is pretty much the cheapest I could get.

19.3lbs as pictured.

Crux by Benji Reynolds, on Flickr

2011 Crux Frameset 52cm
Neuvation R28SL Wheelset
Conti Gatorskin Hardshell Tires
Tubes?
Fizik Arione CX
SRAM Apex Shifters
SRAM Apex Rear Derailleur
SRAM Force Front Derailleur
SRAM Apex Compact Crankset
TRP EuroX Brakes
SRAM 1030 Chain
Jagwire Racer Cables
Ritchey Comp 4-Axis Stem 110mm
FSA Omega Compact Bars 42cm
K-Edge Chain Catcher
K-Edge Garmin Mount
Garmin Edge 500
Rokform iPhone Mount
Shimano M520 Pedals
Arundel Sport Bottle Cages

Areas where I could see myself upgrading to drop weight are the stem, bars, pedals, and crankset. Everything else I think I want to keep pretty cheap.

Do you guys have any ideas for dropping weight while still retaining crashability?