According to Official Guinness Records,
The tallest rideable motorcycle measures 5.10 m (16 ft 8.78 in) tall from the ground to the top of the handlebars. It was constructed by Fabio Reggiani (Italy), and the motorcycle was ridden over a 100-m course at Montecchio Emilia, Italy, on 24 March 2012.
For a complete list of 2012 records, please visit 2012 Guinness Records in Italy.