Originally Posted by alcjphil

The main reason for building a bike with 650 B wheels is to be able to use wider tires. A wheel with a wide 650 B tire will be about the same diameter as a 700 C wheel with a narrow road tire. Frame size has little to do with wheel size. If frame geometry is similar, you would need the same frame size with a 700 c wheel as you would with a 650 b wheel