A road going motorcycle , the Norton Model 18 was launched in 1923 .
A road going motorcycle , the Norton Model 18 was became a best seller , as well as establishing many records , including Alec Bennet 's Senior TT win .
A road going motorcycle , the Norton Model 18 was launched in 1923 and became a best seller , as well as establishing many records , including Alec Bennet 's Senior TT win .