It's getting close to pay day and my purchase of a new bike. I'm getting a single/fixed gear bike for commuting, shopping and general riding about on, so I want to add a rack and panniers to it. I've read the occasional post about peoples heals clipping the bags, and I'm worried this might be more of a factor for someone with big feet. I'm a size 12 and I occasionally clip my heals on my chain stays (washers needed on the pedals to move them out). Is this going to be a big problem when getting panniers to work? Is there a different type of rack that positions the bags further back?