I have a set of Bontrager X-lites with approx 2000 miles on them. For whatever reason I cannot get the rear breaks to grip the rim while breaking. The wheel just rolls right throught the breaks. I tried changing the pad position and even put on brand new break pads. This did not help either.

Is there something I am missing? My front wheel has no problems. Any advice would be much appreciated. I am quite frustrated.

Sounds like there is something with the rim. Do the pads make any squealing sounds - if so, proper toe-in may help a bit.

In any case, I'd start by giving the rims' brake surface a good cleaning with a solvent (acetons or mineral spirits) and possibly a mild abrasive (like a scotchbrite pot scrubber pad). You may have some sort of deposit (or errant chain lube) on the brake track that is impeding braking. Also, use some fine grit sandpaper and lightly sand the face of the brake pads, they could be glazed over or contaminated with whatever is on the rims.

Good luck, make sure you keep us posted on your progress.

'Rear wheel rolls through the brakes.' Take the rear wheel off, and make sure the brakes are working by depressing the rear brake lever, do they almost close up?

How much rear braking are you looking for? Can you lock up the rear wheel? Is the brake lever fully actuated, up against the handlebar?