1. Take a tape measure with you. To stand a bike upright (with the front wheel removed), you generally need about 48". Front-to-back distance usually isn't as critical because you can stick the rear bike wheel between the seats. Be aware, however, that the handlebar will extend probably 8" to 12" farther back toward the tail gate.

2. Do you know what you are getting yourself into? Once you start carrying your bikes this way you'll probably never want to settle for any other way.