I am looking to get a roof rack for a 2007 mazda 3> I need the system but not sure what I need for the basics to put bicycle rack on crossbars.

 

Thule has a great roof rack system. Go to their website and you can build it and know what you need. The suggestion I would give is to go with the "fixed points" installation, much cleaner look. Fixed point means no clamps from the roof to the doors, instead you use the mount that are on the roof. Not too hard to do at all and the mounts are there on all 5 doors. If you are interested,and have a sedan, I can find out are already there too.

Any questions, do not hesitate to ask. Here is a picture.