I've started a search for a new bike.I'm interested in hearing opinions on the makes and models I should look for. I've been riding for just less than a year and currently ride a 58cm Windsor Stratford with Shimano Sora components. I ride 30mi. three times a week.I take just about two hours for my ride. I'm 6' ft and 220lbs. Is it worth it for me to upgrade to a lighter bike(19-20lbs) with Shimano 105 or better? And what about going to drop handlebars versus the straight ones I currently use. One more question, what about buying a used bike?