There's no Norm. Really, it's what your customers want. Like you said, the Bikers want it on the back. It's just a preference.
Some people like big transfers on either front or back. If you're selling to Bikers, and they like it on the back, than make them with designs on the back.
Some people like big transfers on either front or back. If you're selling to Bikers, and they like it on the back, than make them with designs on the back.