Actually HD and Buell have been 100% belt drive for 20 years. My two Harleys have 70K miles and nearly 100K miles on their belts. They have belt guards to prevent stones from getting between the sprocket and the belt, which could cause serious damage. They are completely maintenance free, do not stretch, are clean and very quiet. The biggest disadvantage that I can see with a single gear setup is that it is difficult and expensive to change gearing. I really like the idea with a multispeed internal hub setup such as the Trek Soho.