I built up my commuter with the Nashbar X frame and carbon fork a few years ago. Heel strike was an issue on the original build with Detours Toucan panniers and SunLite rack. I replaced the rack with a Ractime Addit and it really made a difference. Racktime racks are part of Tubus, they use aluminum and are much lower in cost ($55). The Addit rack allows panniers to be mounted lower and further back. The quality of construction (Germany) is excellent!

I happened to have some leftover hardware from SKS fenders and used a short thin stainless steel plate to ease the mounting of both rank and fenders in the lug mounting hole. It helped move the rack a little further back. But, Tubus also offers a pack of hardware separately which contains a similar bracket to help move racks back a bit.

The X frame is very sturdy and allows for disk brakes. --Cheers!!