I am headed to Ohio Saturday (day trip) and I may, or may not, have time to take a spin on the Richland B&O Trail. It would be easier if I could just toss my bike on the rack and go - but am wondering if this might have a strong impact on my gas mileage - it is a trunk rack.

I have a Saris Bones - do they have the potential to become loose over a long drive? That is another consideration - Saturday will include 9 hours of driving... I have the version of the Saris rack that locks. I haven't used it outside of town.