Have a quick search for cycle carriers. Theres a few threads,
Here's a recent one
http://forum.earlybay.com/viewtopic.php?f=1&t=46875&p=390956&hilit=Bike+rack#p390956" onclick="window.open(this.href);return false;
As per the link i use a saris bones carrier on mine, sturdy, simple to use and has a good securing system for the bikes. My bikes are pretty pricey as well so dont want to take any chances